contrib/llvm-project/clang/lib/Sema/SemaInit.cpp

   1 //===--- SemaInit.cpp - Semantic Analysis for Initializers ----------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements semantic analysis for initializers.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/AST/ASTContext.h"
  14 #include "clang/AST/DeclObjC.h"
  15 #include "clang/AST/ExprCXX.h"
  16 #include "clang/AST/ExprObjC.h"
  17 #include "clang/AST/ExprOpenMP.h"
  18 #include "clang/AST/TypeLoc.h"
  19 #include "clang/Basic/TargetInfo.h"
  20 #include "clang/Sema/Designator.h"
  21 #include "clang/Sema/Initialization.h"
  22 #include "clang/Sema/Lookup.h"
  23 #include "clang/Sema/SemaInternal.h"
  24 #include "llvm/ADT/APInt.h"
  25 #include "llvm/ADT/SmallString.h"
  26 #include "llvm/Support/ErrorHandling.h"
  27 #include "llvm/Support/raw_ostream.h"
  28
  29 using namespace clang;
  30
  31 //===----------------------------------------------------------------------===//
  32 // Sema Initialization Checking
  33 //===----------------------------------------------------------------------===//
  34
  35 /// Check whether T is compatible with a wide character type (wchar_t,
  36 /// char16_t or char32_t).
  37 static bool IsWideCharCompatible(QualType T, ASTContext &Context) {
  38   if (Context.typesAreCompatible(Context.getWideCharType(), T))
  39     return true;
  40   if (Context.getLangOpts().CPlusPlus || Context.getLangOpts().C11) {
  41     return Context.typesAreCompatible(Context.Char16Ty, T) ||
  42            Context.typesAreCompatible(Context.Char32Ty, T);
  43   }
  44   return false;
  45 }
  46
  47 enum StringInitFailureKind {
  48   SIF_None,
  49   SIF_NarrowStringIntoWideChar,
  50   SIF_WideStringIntoChar,
  51   SIF_IncompatWideStringIntoWideChar,
  52   SIF_UTF8StringIntoPlainChar,
  53   SIF_PlainStringIntoUTF8Char,
  54   SIF_Other
  55 };
  56
  57 /// Check whether the array of type AT can be initialized by the Init
  58 /// expression by means of string initialization. Returns SIF_None if so,
  59 /// otherwise returns a StringInitFailureKind that describes why the
  60 /// initialization would not work.
  61 static StringInitFailureKind IsStringInit(Expr *Init, const ArrayType *AT,
  62                                           ASTContext &Context) {
  63   if (!isa<ConstantArrayType>(AT) && !isa<IncompleteArrayType>(AT))
  64     return SIF_Other;
  65
  66   // See if this is a string literal or @encode.
  67   Init = Init->IgnoreParens();
  68
  69   // Handle @encode, which is a narrow string.
  70   if (isa<ObjCEncodeExpr>(Init) && AT->getElementType()->isCharType())
  71     return SIF_None;
  72
  73   // Otherwise we can only handle string literals.
  74   StringLiteral *SL = dyn_cast<StringLiteral>(Init);
  75   if (!SL)
  76     return SIF_Other;
  77
  78   const QualType ElemTy =
  79       Context.getCanonicalType(AT->getElementType()).getUnqualifiedType();
  80
  81   switch (SL->getKind()) {
  82   case StringLiteral::UTF8:
  83     // char8_t array can be initialized with a UTF-8 string.
  84     if (ElemTy->isChar8Type())
  85       return SIF_None;
  86     LLVM_FALLTHROUGH;
  87   case StringLiteral::Ascii:
  88     // char array can be initialized with a narrow string.
  89     // Only allow char x[] = "foo";  not char x[] = L"foo";
  90     if (ElemTy->isCharType())
  91       return (SL->getKind() == StringLiteral::UTF8 &&
  92               Context.getLangOpts().Char8)
  93                  ? SIF_UTF8StringIntoPlainChar
  94                  : SIF_None;
  95     if (ElemTy->isChar8Type())
  96       return SIF_PlainStringIntoUTF8Char;
  97     if (IsWideCharCompatible(ElemTy, Context))
  98       return SIF_NarrowStringIntoWideChar;
  99     return SIF_Other;
 100   // C99 6.7.8p15 (with correction from DR343), or C11 6.7.9p15:
 101   // "An array with element type compatible with a qualified or unqualified
 102   // version of wchar_t, char16_t, or char32_t may be initialized by a wide
 103   // string literal with the corresponding encoding prefix (L, u, or U,
 104   // respectively), optionally enclosed in braces.
 105   case StringLiteral::UTF16:
 106     if (Context.typesAreCompatible(Context.Char16Ty, ElemTy))
 107       return SIF_None;
 108     if (ElemTy->isCharType() || ElemTy->isChar8Type())
 109       return SIF_WideStringIntoChar;
 110     if (IsWideCharCompatible(ElemTy, Context))
 111       return SIF_IncompatWideStringIntoWideChar;
 112     return SIF_Other;
 113   case StringLiteral::UTF32:
 114     if (Context.typesAreCompatible(Context.Char32Ty, ElemTy))
 115       return SIF_None;
 116     if (ElemTy->isCharType() || ElemTy->isChar8Type())
 117       return SIF_WideStringIntoChar;
 118     if (IsWideCharCompatible(ElemTy, Context))
 119       return SIF_IncompatWideStringIntoWideChar;
 120     return SIF_Other;
 121   case StringLiteral::Wide:
 122     if (Context.typesAreCompatible(Context.getWideCharType(), ElemTy))
 123       return SIF_None;
 124     if (ElemTy->isCharType() || ElemTy->isChar8Type())
 125       return SIF_WideStringIntoChar;
 126     if (IsWideCharCompatible(ElemTy, Context))
 127       return SIF_IncompatWideStringIntoWideChar;
 128     return SIF_Other;
 129   }
 130
 131   llvm_unreachable("missed a StringLiteral kind?");
 132 }
 133
 134 static StringInitFailureKind IsStringInit(Expr *init, QualType declType,
 135                                           ASTContext &Context) {
 136   const ArrayType *arrayType = Context.getAsArrayType(declType);
 137   if (!arrayType)
 138     return SIF_Other;
 139   return IsStringInit(init, arrayType, Context);
 140 }
 141
 142 /// Update the type of a string literal, including any surrounding parentheses,
 143 /// to match the type of the object which it is initializing.
 144 static void updateStringLiteralType(Expr *E, QualType Ty) {
 145   while (true) {
 146     E->setType(Ty);
 147     E->setValueKind(VK_RValue);
 148     if (isa<StringLiteral>(E) || isa<ObjCEncodeExpr>(E)) {
 149       break;
 150     } else if (ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
 151       E = PE->getSubExpr();
 152     } else if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
 153       assert(UO->getOpcode() == UO_Extension);
 154       E = UO->getSubExpr();
 155     } else if (GenericSelectionExpr *GSE = dyn_cast<GenericSelectionExpr>(E)) {
 156       E = GSE->getResultExpr();
 157     } else if (ChooseExpr *CE = dyn_cast<ChooseExpr>(E)) {
 158       E = CE->getChosenSubExpr();
 159     } else {
 160       llvm_unreachable("unexpected expr in string literal init");
 161     }
 162   }
 163 }
 164
 165 /// Fix a compound literal initializing an array so it's correctly marked
 166 /// as an rvalue.
 167 static void updateGNUCompoundLiteralRValue(Expr *E) {
 168   while (true) {
 169     E->setValueKind(VK_RValue);
 170     if (isa<CompoundLiteralExpr>(E)) {
 171       break;
 172     } else if (ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
 173       E = PE->getSubExpr();
 174     } else if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
 175       assert(UO->getOpcode() == UO_Extension);
 176       E = UO->getSubExpr();
 177     } else if (GenericSelectionExpr *GSE = dyn_cast<GenericSelectionExpr>(E)) {
 178       E = GSE->getResultExpr();
 179     } else if (ChooseExpr *CE = dyn_cast<ChooseExpr>(E)) {
 180       E = CE->getChosenSubExpr();
 181     } else {
 182       llvm_unreachable("unexpected expr in array compound literal init");
 183     }
 184   }
 185 }
 186
 187 static void CheckStringInit(Expr *Str, QualType &DeclT, const ArrayType *AT,
 188                             Sema &S) {
 189   // Get the length of the string as parsed.
 190   auto *ConstantArrayTy =
 191       cast<ConstantArrayType>(Str->getType()->getAsArrayTypeUnsafe());
 192   uint64_t StrLength = ConstantArrayTy->getSize().getZExtValue();
 193
 194   if (const IncompleteArrayType *IAT = dyn_cast<IncompleteArrayType>(AT)) {
 195     // C99 6.7.8p14. We have an array of character type with unknown size
 196     // being initialized to a string literal.
 197     llvm::APInt ConstVal(32, StrLength);
 198     // Return a new array type (C99 6.7.8p22).
 199     DeclT = S.Context.getConstantArrayType(IAT->getElementType(),
 200                                            ConstVal,
 201                                            ArrayType::Normal, 0);
 202     updateStringLiteralType(Str, DeclT);
 203     return;
 204   }
 205
 206   const ConstantArrayType *CAT = cast<ConstantArrayType>(AT);
 207
 208   // We have an array of character type with known size.  However,
 209   // the size may be smaller or larger than the string we are initializing.
 210   // FIXME: Avoid truncation for 64-bit length strings.
 211   if (S.getLangOpts().CPlusPlus) {
 212     if (StringLiteral *SL = dyn_cast<StringLiteral>(Str->IgnoreParens())) {
 213       // For Pascal strings it's OK to strip off the terminating null character,
 214       // so the example below is valid:
 215       //
 216       // unsigned char a[2] = "\pa";
 217       if (SL->isPascal())
 218         StrLength--;
 219     }
 220
 221     // [dcl.init.string]p2
 222     if (StrLength > CAT->getSize().getZExtValue())
 223       S.Diag(Str->getBeginLoc(),
 224              diag::err_initializer_string_for_char_array_too_long)
 225           << Str->getSourceRange();
 226   } else {
 227     // C99 6.7.8p14.
 228     if (StrLength-1 > CAT->getSize().getZExtValue())
 229       S.Diag(Str->getBeginLoc(),
 230              diag::ext_initializer_string_for_char_array_too_long)
 231           << Str->getSourceRange();
 232   }
 233
 234   // Set the type to the actual size that we are initializing.  If we have
 235   // something like:
 236   //   char x[1] = "foo";
 237   // then this will set the string literal's type to char[1].
 238   updateStringLiteralType(Str, DeclT);
 239 }
 240
 241 //===----------------------------------------------------------------------===//
 242 // Semantic checking for initializer lists.
 243 //===----------------------------------------------------------------------===//
 244
 245 namespace {
 246
 247 /// Semantic checking for initializer lists.
 248 ///
 249 /// The InitListChecker class contains a set of routines that each
 250 /// handle the initialization of a certain kind of entity, e.g.,
 251 /// arrays, vectors, struct/union types, scalars, etc. The
 252 /// InitListChecker itself performs a recursive walk of the subobject
 253 /// structure of the type to be initialized, while stepping through
 254 /// the initializer list one element at a time. The IList and Index
 255 /// parameters to each of the Check* routines contain the active
 256 /// (syntactic) initializer list and the index into that initializer
 257 /// list that represents the current initializer. Each routine is
 258 /// responsible for moving that Index forward as it consumes elements.
 259 ///
 260 /// Each Check* routine also has a StructuredList/StructuredIndex
 261 /// arguments, which contains the current "structured" (semantic)
 262 /// initializer list and the index into that initializer list where we
 263 /// are copying initializers as we map them over to the semantic
 264 /// list. Once we have completed our recursive walk of the subobject
 265 /// structure, we will have constructed a full semantic initializer
 266 /// list.
 267 ///
 268 /// C99 designators cause changes in the initializer list traversal,
 269 /// because they make the initialization "jump" into a specific
 270 /// subobject and then continue the initialization from that
 271 /// point. CheckDesignatedInitializer() recursively steps into the
 272 /// designated subobject and manages backing out the recursion to
 273 /// initialize the subobjects after the one designated.
 274 class InitListChecker {
 275   Sema &SemaRef;
 276   bool hadError;
 277   bool VerifyOnly; // no diagnostics, no structure building
 278   bool TreatUnavailableAsInvalid; // Used only in VerifyOnly mode.
 279   llvm::DenseMap<InitListExpr *, InitListExpr *> SyntacticToSemantic;
 280   InitListExpr *FullyStructuredList;
 281
 282   void CheckImplicitInitList(const InitializedEntity &Entity,
 283                              InitListExpr *ParentIList, QualType T,
 284                              unsigned &Index, InitListExpr *StructuredList,
 285                              unsigned &StructuredIndex);
 286   void CheckExplicitInitList(const InitializedEntity &Entity,
 287                              InitListExpr *IList, QualType &T,
 288                              InitListExpr *StructuredList,
 289                              bool TopLevelObject = false);
 290   void CheckListElementTypes(const InitializedEntity &Entity,
 291                              InitListExpr *IList, QualType &DeclType,
 292                              bool SubobjectIsDesignatorContext,
 293                              unsigned &Index,
 294                              InitListExpr *StructuredList,
 295                              unsigned &StructuredIndex,
 296                              bool TopLevelObject = false);
 297   void CheckSubElementType(const InitializedEntity &Entity,
 298                            InitListExpr *IList, QualType ElemType,
 299                            unsigned &Index,
 300                            InitListExpr *StructuredList,
 301                            unsigned &StructuredIndex);
 302   void CheckComplexType(const InitializedEntity &Entity,
 303                         InitListExpr *IList, QualType DeclType,
 304                         unsigned &Index,
 305                         InitListExpr *StructuredList,
 306                         unsigned &StructuredIndex);
 307   void CheckScalarType(const InitializedEntity &Entity,
 308                        InitListExpr *IList, QualType DeclType,
 309                        unsigned &Index,
 310                        InitListExpr *StructuredList,
 311                        unsigned &StructuredIndex);
 312   void CheckReferenceType(const InitializedEntity &Entity,
 313                           InitListExpr *IList, QualType DeclType,
 314                           unsigned &Index,
 315                           InitListExpr *StructuredList,
 316                           unsigned &StructuredIndex);
 317   void CheckVectorType(const InitializedEntity &Entity,
 318                        InitListExpr *IList, QualType DeclType, unsigned &Index,
 319                        InitListExpr *StructuredList,
 320                        unsigned &StructuredIndex);
 321   void CheckStructUnionTypes(const InitializedEntity &Entity,
 322                              InitListExpr *IList, QualType DeclType,
 323                              CXXRecordDecl::base_class_range Bases,
 324                              RecordDecl::field_iterator Field,
 325                              bool SubobjectIsDesignatorContext, unsigned &Index,
 326                              InitListExpr *StructuredList,
 327                              unsigned &StructuredIndex,
 328                              bool TopLevelObject = false);
 329   void CheckArrayType(const InitializedEntity &Entity,
 330                       InitListExpr *IList, QualType &DeclType,
 331                       llvm::APSInt elementIndex,
 332                       bool SubobjectIsDesignatorContext, unsigned &Index,
 333                       InitListExpr *StructuredList,
 334                       unsigned &StructuredIndex);
 335   bool CheckDesignatedInitializer(const InitializedEntity &Entity,
 336                                   InitListExpr *IList, DesignatedInitExpr *DIE,
 337                                   unsigned DesigIdx,
 338                                   QualType &CurrentObjectType,
 339                                   RecordDecl::field_iterator *NextField,
 340                                   llvm::APSInt *NextElementIndex,
 341                                   unsigned &Index,
 342                                   InitListExpr *StructuredList,
 343                                   unsigned &StructuredIndex,
 344                                   bool FinishSubobjectInit,
 345                                   bool TopLevelObject);
 346   InitListExpr *getStructuredSubobjectInit(InitListExpr *IList, unsigned Index,
 347                                            QualType CurrentObjectType,
 348                                            InitListExpr *StructuredList,
 349                                            unsigned StructuredIndex,
 350                                            SourceRange InitRange,
 351                                            bool IsFullyOverwritten = false);
 352   void UpdateStructuredListElement(InitListExpr *StructuredList,
 353                                    unsigned &StructuredIndex,
 354                                    Expr *expr);
 355   int numArrayElements(QualType DeclType);
 356   int numStructUnionElements(QualType DeclType);
 357
 358   static ExprResult PerformEmptyInit(Sema &SemaRef,
 359                                      SourceLocation Loc,
 360                                      const InitializedEntity &Entity,
 361                                      bool VerifyOnly,
 362                                      bool TreatUnavailableAsInvalid);
 363
 364   // Explanation on the "FillWithNoInit" mode:
 365   //
 366   // Assume we have the following definitions (Case#1):
 367   // struct P { char x[6][6]; } xp = { .x[1] = "bar" };
 368   // struct PP { struct P lp; } l = { .lp = xp, .lp.x[1][2] = 'f' };
 369   //
 370   // l.lp.x[1][0..1] should not be filled with implicit initializers because the
 371   // "base" initializer "xp" will provide values for them; l.lp.x[1] will be "baf".
 372   //
 373   // But if we have (Case#2):
 374   // struct PP l = { .lp = xp, .lp.x[1] = { [2] = 'f' } };
 375   //
 376   // l.lp.x[1][0..1] are implicitly initialized and do not use values from the
 377   // "base" initializer; l.lp.x[1] will be "\0\0f\0\0\0".
 378   //
 379   // To distinguish Case#1 from Case#2, and also to avoid leaving many "holes"
 380   // in the InitListExpr, the "holes" in Case#1 are filled not with empty
 381   // initializers but with special "NoInitExpr" place holders, which tells the
 382   // CodeGen not to generate any initializers for these parts.
 383   void FillInEmptyInitForBase(unsigned Init, const CXXBaseSpecifier &Base,
 384                               const InitializedEntity &ParentEntity,
 385                               InitListExpr *ILE, bool &RequiresSecondPass,
 386                               bool FillWithNoInit);
 387   void FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
 388                                const InitializedEntity &ParentEntity,
 389                                InitListExpr *ILE, bool &RequiresSecondPass,
 390                                bool FillWithNoInit = false);
 391   void FillInEmptyInitializations(const InitializedEntity &Entity,
 392                                   InitListExpr *ILE, bool &RequiresSecondPass,
 393                                   InitListExpr *OuterILE, unsigned OuterIndex,
 394                                   bool FillWithNoInit = false);
 395   bool CheckFlexibleArrayInit(const InitializedEntity &Entity,
 396                               Expr *InitExpr, FieldDecl *Field,
 397                               bool TopLevelObject);
 398   void CheckEmptyInitializable(const InitializedEntity &Entity,
 399                                SourceLocation Loc);
 400
 401 public:
 402   InitListChecker(Sema &S, const InitializedEntity &Entity,
 403                   InitListExpr *IL, QualType &T, bool VerifyOnly,
 404                   bool TreatUnavailableAsInvalid);
 405   bool HadError() { return hadError; }
 406
 407   // Retrieves the fully-structured initializer list used for
 408   // semantic analysis and code generation.
 409   InitListExpr *getFullyStructuredList() const { return FullyStructuredList; }
 410 };
 411
 412 } // end anonymous namespace
 413
 414 ExprResult InitListChecker::PerformEmptyInit(Sema &SemaRef,
 415                                              SourceLocation Loc,
 416                                              const InitializedEntity &Entity,
 417                                              bool VerifyOnly,
 418                                              bool TreatUnavailableAsInvalid) {
 419   InitializationKind Kind = InitializationKind::CreateValue(Loc, Loc, Loc,
 420                                                             true);
 421   MultiExprArg SubInit;
 422   Expr *InitExpr;
 423   InitListExpr DummyInitList(SemaRef.Context, Loc, None, Loc);
 424
 425   // C++ [dcl.init.aggr]p7:
 426   //   If there are fewer initializer-clauses in the list than there are
 427   //   members in the aggregate, then each member not explicitly initialized
 428   //   ...
 429   bool EmptyInitList = SemaRef.getLangOpts().CPlusPlus11 &&
 430       Entity.getType()->getBaseElementTypeUnsafe()->isRecordType();
 431   if (EmptyInitList) {
 432     // C++1y / DR1070:
 433     //   shall be initialized [...] from an empty initializer list.
 434     //
 435     // We apply the resolution of this DR to C++11 but not C++98, since C++98
 436     // does not have useful semantics for initialization from an init list.
 437     // We treat this as copy-initialization, because aggregate initialization
 438     // always performs copy-initialization on its elements.
 439     //
 440     // Only do this if we're initializing a class type, to avoid filling in
 441     // the initializer list where possible.
 442     InitExpr = VerifyOnly ? &DummyInitList : new (SemaRef.Context)
 443                    InitListExpr(SemaRef.Context, Loc, None, Loc);
 444     InitExpr->setType(SemaRef.Context.VoidTy);
 445     SubInit = InitExpr;
 446     Kind = InitializationKind::CreateCopy(Loc, Loc);
 447   } else {
 448     // C++03:
 449     //   shall be value-initialized.
 450   }
 451
 452   InitializationSequence InitSeq(SemaRef, Entity, Kind, SubInit);
 453   // libstdc++4.6 marks the vector default constructor as explicit in
 454   // _GLIBCXX_DEBUG mode, so recover using the C++03 logic in that case.
 455   // stlport does so too. Look for std::__debug for libstdc++, and for
 456   // std:: for stlport.  This is effectively a compiler-side implementation of
 457   // LWG2193.
 458   if (!InitSeq && EmptyInitList && InitSeq.getFailureKind() ==
 459           InitializationSequence::FK_ExplicitConstructor) {
 460     OverloadCandidateSet::iterator Best;
 461     OverloadingResult O =
 462         InitSeq.getFailedCandidateSet()
 463             .BestViableFunction(SemaRef, Kind.getLocation(), Best);
 464     (void)O;
 465     assert(O == OR_Success && "Inconsistent overload resolution");
 466     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
 467     CXXRecordDecl *R = CtorDecl->getParent();
 468
 469     if (CtorDecl->getMinRequiredArguments() == 0 &&
 470         CtorDecl->isExplicit() && R->getDeclName() &&
 471         SemaRef.SourceMgr.isInSystemHeader(CtorDecl->getLocation())) {
 472       bool IsInStd = false;
 473       for (NamespaceDecl *ND = dyn_cast<NamespaceDecl>(R->getDeclContext());
 474            ND && !IsInStd; ND = dyn_cast<NamespaceDecl>(ND->getParent())) {
 475         if (SemaRef.getStdNamespace()->InEnclosingNamespaceSetOf(ND))
 476           IsInStd = true;
 477       }
 478
 479       if (IsInStd && llvm::StringSwitch<bool>(R->getName())
 480               .Cases("basic_string", "deque", "forward_list", true)
 481               .Cases("list", "map", "multimap", "multiset", true)
 482               .Cases("priority_queue", "queue", "set", "stack", true)
 483               .Cases("unordered_map", "unordered_set", "vector", true)
 484               .Default(false)) {
 485         InitSeq.InitializeFrom(
 486             SemaRef, Entity,
 487             InitializationKind::CreateValue(Loc, Loc, Loc, true),
 488             MultiExprArg(), /*TopLevelOfInitList=*/false,
 489             TreatUnavailableAsInvalid);
 490         // Emit a warning for this.  System header warnings aren't shown
 491         // by default, but people working on system headers should see it.
 492         if (!VerifyOnly) {
 493           SemaRef.Diag(CtorDecl->getLocation(),
 494                        diag::warn_invalid_initializer_from_system_header);
 495           if (Entity.getKind() == InitializedEntity::EK_Member)
 496             SemaRef.Diag(Entity.getDecl()->getLocation(),
 497                          diag::note_used_in_initialization_here);
 498           else if (Entity.getKind() == InitializedEntity::EK_ArrayElement)
 499             SemaRef.Diag(Loc, diag::note_used_in_initialization_here);
 500         }
 501       }
 502     }
 503   }
 504   if (!InitSeq) {
 505     if (!VerifyOnly) {
 506       InitSeq.Diagnose(SemaRef, Entity, Kind, SubInit);
 507       if (Entity.getKind() == InitializedEntity::EK_Member)
 508         SemaRef.Diag(Entity.getDecl()->getLocation(),
 509                      diag::note_in_omitted_aggregate_initializer)
 510           << /*field*/1 << Entity.getDecl();
 511       else if (Entity.getKind() == InitializedEntity::EK_ArrayElement) {
 512         bool IsTrailingArrayNewMember =
 513             Entity.getParent() &&
 514             Entity.getParent()->isVariableLengthArrayNew();
 515         SemaRef.Diag(Loc, diag::note_in_omitted_aggregate_initializer)
 516           << (IsTrailingArrayNewMember ? 2 : /*array element*/0)
 517           << Entity.getElementIndex();
 518       }
 519     }
 520     return ExprError();
 521   }
 522
 523   return VerifyOnly ? ExprResult(static_cast<Expr *>(nullptr))
 524                     : InitSeq.Perform(SemaRef, Entity, Kind, SubInit);
 525 }
 526
 527 void InitListChecker::CheckEmptyInitializable(const InitializedEntity &Entity,
 528                                               SourceLocation Loc) {
 529   assert(VerifyOnly &&
 530          "CheckEmptyInitializable is only inteded for verification mode.");
 531   if (PerformEmptyInit(SemaRef, Loc, Entity, /*VerifyOnly*/true,
 532                        TreatUnavailableAsInvalid).isInvalid())
 533     hadError = true;
 534 }
 535
 536 void InitListChecker::FillInEmptyInitForBase(
 537     unsigned Init, const CXXBaseSpecifier &Base,
 538     const InitializedEntity &ParentEntity, InitListExpr *ILE,
 539     bool &RequiresSecondPass, bool FillWithNoInit) {
 540   assert(Init < ILE->getNumInits() && "should have been expanded");
 541
 542   InitializedEntity BaseEntity = InitializedEntity::InitializeBase(
 543       SemaRef.Context, &Base, false, &ParentEntity);
 544
 545   if (!ILE->getInit(Init)) {
 546     ExprResult BaseInit =
 547         FillWithNoInit
 548             ? new (SemaRef.Context) NoInitExpr(Base.getType())
 549             : PerformEmptyInit(SemaRef, ILE->getEndLoc(), BaseEntity,
 550                                /*VerifyOnly*/ false, TreatUnavailableAsInvalid);
 551     if (BaseInit.isInvalid()) {
 552       hadError = true;
 553       return;
 554     }
 555
 556     ILE->setInit(Init, BaseInit.getAs<Expr>());
 557   } else if (InitListExpr *InnerILE =
 558                  dyn_cast<InitListExpr>(ILE->getInit(Init))) {
 559     FillInEmptyInitializations(BaseEntity, InnerILE, RequiresSecondPass,
 560                                ILE, Init, FillWithNoInit);
 561   } else if (DesignatedInitUpdateExpr *InnerDIUE =
 562                dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init))) {
 563     FillInEmptyInitializations(BaseEntity, InnerDIUE->getUpdater(),
 564                                RequiresSecondPass, ILE, Init,
 565                                /*FillWithNoInit =*/true);
 566   }
 567 }
 568
 569 void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
 570                                         const InitializedEntity &ParentEntity,
 571                                               InitListExpr *ILE,
 572                                               bool &RequiresSecondPass,
 573                                               bool FillWithNoInit) {
 574   SourceLocation Loc = ILE->getEndLoc();
 575   unsigned NumInits = ILE->getNumInits();
 576   InitializedEntity MemberEntity
 577     = InitializedEntity::InitializeMember(Field, &ParentEntity);
 578
 579   if (const RecordType *RType = ILE->getType()->getAs<RecordType>())
 580     if (!RType->getDecl()->isUnion())
 581       assert(Init < NumInits && "This ILE should have been expanded");
 582
 583   if (Init >= NumInits || !ILE->getInit(Init)) {
 584     if (FillWithNoInit) {
 585       Expr *Filler = new (SemaRef.Context) NoInitExpr(Field->getType());
 586       if (Init < NumInits)
 587         ILE->setInit(Init, Filler);
 588       else
 589         ILE->updateInit(SemaRef.Context, Init, Filler);
 590       return;
 591     }
 592     // C++1y [dcl.init.aggr]p7:
 593     //   If there are fewer initializer-clauses in the list than there are
 594     //   members in the aggregate, then each member not explicitly initialized
 595     //   shall be initialized from its brace-or-equal-initializer [...]
 596     if (Field->hasInClassInitializer()) {
 597       ExprResult DIE = SemaRef.BuildCXXDefaultInitExpr(Loc, Field);
 598       if (DIE.isInvalid()) {
 599         hadError = true;
 600         return;
 601       }
 602       SemaRef.checkInitializerLifetime(MemberEntity, DIE.get());
 603       if (Init < NumInits)
 604         ILE->setInit(Init, DIE.get());
 605       else {
 606         ILE->updateInit(SemaRef.Context, Init, DIE.get());
 607         RequiresSecondPass = true;
 608       }
 609       return;
 610     }
 611
 612     if (Field->getType()->isReferenceType()) {
 613       // C++ [dcl.init.aggr]p9:
 614       //   If an incomplete or empty initializer-list leaves a
 615       //   member of reference type uninitialized, the program is
 616       //   ill-formed.
 617       SemaRef.Diag(Loc, diag::err_init_reference_member_uninitialized)
 618         << Field->getType()
 619         << ILE->getSyntacticForm()->getSourceRange();
 620       SemaRef.Diag(Field->getLocation(),
 621                    diag::note_uninit_reference_member);
 622       hadError = true;
 623       return;
 624     }
 625
 626     ExprResult MemberInit = PerformEmptyInit(SemaRef, Loc, MemberEntity,
 627                                              /*VerifyOnly*/false,
 628                                              TreatUnavailableAsInvalid);
 629     if (MemberInit.isInvalid()) {
 630       hadError = true;
 631       return;
 632     }
 633
 634     if (hadError) {
 635       // Do nothing
 636     } else if (Init < NumInits) {
 637       ILE->setInit(Init, MemberInit.getAs<Expr>());
 638     } else if (!isa<ImplicitValueInitExpr>(MemberInit.get())) {
 639       // Empty initialization requires a constructor call, so
 640       // extend the initializer list to include the constructor
 641       // call and make a note that we'll need to take another pass
 642       // through the initializer list.
 643       ILE->updateInit(SemaRef.Context, Init, MemberInit.getAs<Expr>());
 644       RequiresSecondPass = true;
 645     }
 646   } else if (InitListExpr *InnerILE
 647                = dyn_cast<InitListExpr>(ILE->getInit(Init)))
 648     FillInEmptyInitializations(MemberEntity, InnerILE,
 649                                RequiresSecondPass, ILE, Init, FillWithNoInit);
 650   else if (DesignatedInitUpdateExpr *InnerDIUE
 651                = dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init)))
 652     FillInEmptyInitializations(MemberEntity, InnerDIUE->getUpdater(),
 653                                RequiresSecondPass, ILE, Init,
 654                                /*FillWithNoInit =*/true);
 655 }
 656
 657 /// Recursively replaces NULL values within the given initializer list
 658 /// with expressions that perform value-initialization of the
 659 /// appropriate type, and finish off the InitListExpr formation.
 660 void
 661 InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
 662                                             InitListExpr *ILE,
 663                                             bool &RequiresSecondPass,
 664                                             InitListExpr *OuterILE,
 665                                             unsigned OuterIndex,
 666                                             bool FillWithNoInit) {
 667   assert((ILE->getType() != SemaRef.Context.VoidTy) &&
 668          "Should not have void type");
 669
 670   // If this is a nested initializer list, we might have changed its contents
 671   // (and therefore some of its properties, such as instantiation-dependence)
 672   // while filling it in. Inform the outer initializer list so that its state
 673   // can be updated to match.
 674   // FIXME: We should fully build the inner initializers before constructing
 675   // the outer InitListExpr instead of mutating AST nodes after they have
 676   // been used as subexpressions of other nodes.
 677   struct UpdateOuterILEWithUpdatedInit {
 678     InitListExpr *Outer;
 679     unsigned OuterIndex;
 680     ~UpdateOuterILEWithUpdatedInit() {
 681       if (Outer)
 682         Outer->setInit(OuterIndex, Outer->getInit(OuterIndex));
 683     }
 684   } UpdateOuterRAII = {OuterILE, OuterIndex};
 685
 686   // A transparent ILE is not performing aggregate initialization and should
 687   // not be filled in.
 688   if (ILE->isTransparent())
 689     return;
 690
 691   if (const RecordType *RType = ILE->getType()->getAs<RecordType>()) {
 692     const RecordDecl *RDecl = RType->getDecl();
 693     if (RDecl->isUnion() && ILE->getInitializedFieldInUnion())
 694       FillInEmptyInitForField(0, ILE->getInitializedFieldInUnion(),
 695                               Entity, ILE, RequiresSecondPass, FillWithNoInit);
 696     else if (RDecl->isUnion() && isa<CXXRecordDecl>(RDecl) &&
 697              cast<CXXRecordDecl>(RDecl)->hasInClassInitializer()) {
 698       for (auto *Field : RDecl->fields()) {
 699         if (Field->hasInClassInitializer()) {
 700           FillInEmptyInitForField(0, Field, Entity, ILE, RequiresSecondPass,
 701                                   FillWithNoInit);
 702           break;
 703         }
 704       }
 705     } else {
 706       // The fields beyond ILE->getNumInits() are default initialized, so in
 707       // order to leave them uninitialized, the ILE is expanded and the extra
 708       // fields are then filled with NoInitExpr.
 709       unsigned NumElems = numStructUnionElements(ILE->getType());
 710       if (RDecl->hasFlexibleArrayMember())
 711         ++NumElems;
 712       if (ILE->getNumInits() < NumElems)
 713         ILE->resizeInits(SemaRef.Context, NumElems);
 714
 715       unsigned Init = 0;
 716
 717       if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RDecl)) {
 718         for (auto &Base : CXXRD->bases()) {
 719           if (hadError)
 720             return;
 721
 722           FillInEmptyInitForBase(Init, Base, Entity, ILE, RequiresSecondPass,
 723                                  FillWithNoInit);
 724           ++Init;
 725         }
 726       }
 727
 728       for (auto *Field : RDecl->fields()) {
 729         if (Field->isUnnamedBitfield())
 730           continue;
 731
 732         if (hadError)
 733           return;
 734
 735         FillInEmptyInitForField(Init, Field, Entity, ILE, RequiresSecondPass,
 736                                 FillWithNoInit);
 737         if (hadError)
 738           return;
 739
 740         ++Init;
 741
 742         // Only look at the first initialization of a union.
 743         if (RDecl->isUnion())
 744           break;
 745       }
 746     }
 747
 748     return;
 749   }
 750
 751   QualType ElementType;
 752
 753   InitializedEntity ElementEntity = Entity;
 754   unsigned NumInits = ILE->getNumInits();
 755   unsigned NumElements = NumInits;
 756   if (const ArrayType *AType = SemaRef.Context.getAsArrayType(ILE->getType())) {
 757     ElementType = AType->getElementType();
 758     if (const auto *CAType = dyn_cast<ConstantArrayType>(AType))
 759       NumElements = CAType->getSize().getZExtValue();
 760     // For an array new with an unknown bound, ask for one additional element
 761     // in order to populate the array filler.
 762     if (Entity.isVariableLengthArrayNew())
 763       ++NumElements;
 764     ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
 765                                                          0, Entity);
 766   } else if (const VectorType *VType = ILE->getType()->getAs<VectorType>()) {
 767     ElementType = VType->getElementType();
 768     NumElements = VType->getNumElements();
 769     ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
 770                                                          0, Entity);
 771   } else
 772     ElementType = ILE->getType();
 773
 774   for (unsigned Init = 0; Init != NumElements; ++Init) {
 775     if (hadError)
 776       return;
 777
 778     if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement ||
 779         ElementEntity.getKind() == InitializedEntity::EK_VectorElement)
 780       ElementEntity.setElementIndex(Init);
 781
 782     if (Init >= NumInits && ILE->hasArrayFiller())
 783       return;
 784
 785     Expr *InitExpr = (Init < NumInits ? ILE->getInit(Init) : nullptr);
 786     if (!InitExpr && Init < NumInits && ILE->hasArrayFiller())
 787       ILE->setInit(Init, ILE->getArrayFiller());
 788     else if (!InitExpr && !ILE->hasArrayFiller()) {
 789       Expr *Filler = nullptr;
 790
 791       if (FillWithNoInit)
 792         Filler = new (SemaRef.Context) NoInitExpr(ElementType);
 793       else {
 794         ExprResult ElementInit =
 795             PerformEmptyInit(SemaRef, ILE->getEndLoc(), ElementEntity,
 796                              /*VerifyOnly*/ false, TreatUnavailableAsInvalid);
 797         if (ElementInit.isInvalid()) {
 798           hadError = true;
 799           return;
 800         }
 801
 802         Filler = ElementInit.getAs<Expr>();
 803       }
 804
 805       if (hadError) {
 806         // Do nothing
 807       } else if (Init < NumInits) {
 808         // For arrays, just set the expression used for value-initialization
 809         // of the "holes" in the array.
 810         if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement)
 811           ILE->setArrayFiller(Filler);
 812         else
 813           ILE->setInit(Init, Filler);
 814       } else {
 815         // For arrays, just set the expression used for value-initialization
 816         // of the rest of elements and exit.
 817         if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement) {
 818           ILE->setArrayFiller(Filler);
 819           return;
 820         }
 821
 822         if (!isa<ImplicitValueInitExpr>(Filler) && !isa<NoInitExpr>(Filler)) {
 823           // Empty initialization requires a constructor call, so
 824           // extend the initializer list to include the constructor
 825           // call and make a note that we'll need to take another pass
 826           // through the initializer list.
 827           ILE->updateInit(SemaRef.Context, Init, Filler);
 828           RequiresSecondPass = true;
 829         }
 830       }
 831     } else if (InitListExpr *InnerILE
 832                  = dyn_cast_or_null<InitListExpr>(InitExpr))
 833       FillInEmptyInitializations(ElementEntity, InnerILE, RequiresSecondPass,
 834                                  ILE, Init, FillWithNoInit);
 835     else if (DesignatedInitUpdateExpr *InnerDIUE
 836                  = dyn_cast_or_null<DesignatedInitUpdateExpr>(InitExpr))
 837       FillInEmptyInitializations(ElementEntity, InnerDIUE->getUpdater(),
 838                                  RequiresSecondPass, ILE, Init,
 839                                  /*FillWithNoInit =*/true);
 840   }
 841 }
 842
 843 InitListChecker::InitListChecker(Sema &S, const InitializedEntity &Entity,
 844                                  InitListExpr *IL, QualType &T,
 845                                  bool VerifyOnly,
 846                                  bool TreatUnavailableAsInvalid)
 847   : SemaRef(S), VerifyOnly(VerifyOnly),
 848     TreatUnavailableAsInvalid(TreatUnavailableAsInvalid) {
 849   // FIXME: Check that IL isn't already the semantic form of some other
 850   // InitListExpr. If it is, we'd create a broken AST.
 851
 852   hadError = false;
 853
 854   FullyStructuredList =
 855       getStructuredSubobjectInit(IL, 0, T, nullptr, 0, IL->getSourceRange());
 856   CheckExplicitInitList(Entity, IL, T, FullyStructuredList,
 857                         /*TopLevelObject=*/true);
 858
 859   if (!hadError && !VerifyOnly) {
 860     bool RequiresSecondPass = false;
 861     FillInEmptyInitializations(Entity, FullyStructuredList, RequiresSecondPass,
 862                                /*OuterILE=*/nullptr, /*OuterIndex=*/0);
 863     if (RequiresSecondPass && !hadError)
 864       FillInEmptyInitializations(Entity, FullyStructuredList,
 865                                  RequiresSecondPass, nullptr, 0);
 866   }
 867 }
 868
 869 int InitListChecker::numArrayElements(QualType DeclType) {
 870   // FIXME: use a proper constant
 871   int maxElements = 0x7FFFFFFF;
 872   if (const ConstantArrayType *CAT =
 873         SemaRef.Context.getAsConstantArrayType(DeclType)) {
 874     maxElements = static_cast<int>(CAT->getSize().getZExtValue());
 875   }
 876   return maxElements;
 877 }
 878
 879 int InitListChecker::numStructUnionElements(QualType DeclType) {
 880   RecordDecl *structDecl = DeclType->getAs<RecordType>()->getDecl();
 881   int InitializableMembers = 0;
 882   if (auto *CXXRD = dyn_cast<CXXRecordDecl>(structDecl))
 883     InitializableMembers += CXXRD->getNumBases();
 884   for (const auto *Field : structDecl->fields())
 885     if (!Field->isUnnamedBitfield())
 886       ++InitializableMembers;
 887
 888   if (structDecl->isUnion())
 889     return std::min(InitializableMembers, 1);
 890   return InitializableMembers - structDecl->hasFlexibleArrayMember();
 891 }
 892
 893 /// Determine whether Entity is an entity for which it is idiomatic to elide
 894 /// the braces in aggregate initialization.
 895 static bool isIdiomaticBraceElisionEntity(const InitializedEntity &Entity) {
 896   // Recursive initialization of the one and only field within an aggregate
 897   // class is considered idiomatic. This case arises in particular for
 898   // initialization of std::array, where the C++ standard suggests the idiom of
 899   //
 900   //   std::array<T, N> arr = {1, 2, 3};
 901   //
 902   // (where std::array is an aggregate struct containing a single array field.
 903
 904   // FIXME: Should aggregate initialization of a struct with a single
 905   // base class and no members also suppress the warning?
 906   if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
 907     return false;
 908
 909   auto *ParentRD =
 910       Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
 911   if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
 912     if (CXXRD->getNumBases())
 913       return false;
 914
 915   auto FieldIt = ParentRD->field_begin();
 916   assert(FieldIt != ParentRD->field_end() &&
 917          "no fields but have initializer for member?");
 918   return ++FieldIt == ParentRD->field_end();
 919 }
 920
 921 /// Check whether the range of the initializer \p ParentIList from element
 922 /// \p Index onwards can be used to initialize an object of type \p T. Update
 923 /// \p Index to indicate how many elements of the list were consumed.
 924 ///
 925 /// This also fills in \p StructuredList, from element \p StructuredIndex
 926 /// onwards, with the fully-braced, desugared form of the initialization.
 927 void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
 928                                             InitListExpr *ParentIList,
 929                                             QualType T, unsigned &Index,
 930                                             InitListExpr *StructuredList,
 931                                             unsigned &StructuredIndex) {
 932   int maxElements = 0;
 933
 934   if (T->isArrayType())
 935     maxElements = numArrayElements(T);
 936   else if (T->isRecordType())
 937     maxElements = numStructUnionElements(T);
 938   else if (T->isVectorType())
 939     maxElements = T->getAs<VectorType>()->getNumElements();
 940   else
 941     llvm_unreachable("CheckImplicitInitList(): Illegal type");
 942
 943   if (maxElements == 0) {
 944     if (!VerifyOnly)
 945       SemaRef.Diag(ParentIList->getInit(Index)->getBeginLoc(),
 946                    diag::err_implicit_empty_initializer);
 947     ++Index;
 948     hadError = true;
 949     return;
 950   }
 951
 952   // Build a structured initializer list corresponding to this subobject.
 953   InitListExpr *StructuredSubobjectInitList = getStructuredSubobjectInit(
 954       ParentIList, Index, T, StructuredList, StructuredIndex,
 955       SourceRange(ParentIList->getInit(Index)->getBeginLoc(),
 956                   ParentIList->getSourceRange().getEnd()));
 957   unsigned StructuredSubobjectInitIndex = 0;
 958
 959   // Check the element types and build the structural subobject.
 960   unsigned StartIndex = Index;
 961   CheckListElementTypes(Entity, ParentIList, T,
 962                         /*SubobjectIsDesignatorContext=*/false, Index,
 963                         StructuredSubobjectInitList,
 964                         StructuredSubobjectInitIndex);
 965
 966   if (!VerifyOnly) {
 967     StructuredSubobjectInitList->setType(T);
 968
 969     unsigned EndIndex = (Index == StartIndex? StartIndex : Index - 1);
 970     // Update the structured sub-object initializer so that it's ending
 971     // range corresponds with the end of the last initializer it used.
 972     if (EndIndex < ParentIList->getNumInits() &&
 973         ParentIList->getInit(EndIndex)) {
 974       SourceLocation EndLoc
 975         = ParentIList->getInit(EndIndex)->getSourceRange().getEnd();
 976       StructuredSubobjectInitList->setRBraceLoc(EndLoc);
 977     }
 978
 979     // Complain about missing braces.
 980     if ((T->isArrayType() || T->isRecordType()) &&
 981         !ParentIList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) &&
 982         !isIdiomaticBraceElisionEntity(Entity)) {
 983       SemaRef.Diag(StructuredSubobjectInitList->getBeginLoc(),
 984                    diag::warn_missing_braces)
 985           << StructuredSubobjectInitList->getSourceRange()
 986           << FixItHint::CreateInsertion(
 987                  StructuredSubobjectInitList->getBeginLoc(), "{")
 988           << FixItHint::CreateInsertion(
 989                  SemaRef.getLocForEndOfToken(
 990                      StructuredSubobjectInitList->getEndLoc()),
 991                  "}");
 992     }
 993
 994     // Warn if this type won't be an aggregate in future versions of C++.
 995     auto *CXXRD = T->getAsCXXRecordDecl();
 996     if (CXXRD && CXXRD->hasUserDeclaredConstructor()) {
 997       SemaRef.Diag(StructuredSubobjectInitList->getBeginLoc(),
 998                    diag::warn_cxx2a_compat_aggregate_init_with_ctors)
 999           << StructuredSubobjectInitList->getSourceRange() << T;
1000     }
1001   }
1002 }
1003
1004 /// Warn that \p Entity was of scalar type and was initialized by a
1005 /// single-element braced initializer list.
1006 static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
1007                                  SourceRange Braces) {
1008   // Don't warn during template instantiation. If the initialization was
1009   // non-dependent, we warned during the initial parse; otherwise, the
1010   // type might not be scalar in some uses of the template.
1011   if (S.inTemplateInstantiation())
1012     return;
1013
1014   unsigned DiagID = 0;
1015
1016   switch (Entity.getKind()) {
1017   case InitializedEntity::EK_VectorElement:
1018   case InitializedEntity::EK_ComplexElement:
1019   case InitializedEntity::EK_ArrayElement:
1020   case InitializedEntity::EK_Parameter:
1021   case InitializedEntity::EK_Parameter_CF_Audited:
1022   case InitializedEntity::EK_Result:
1023     // Extra braces here are suspicious.
1024     DiagID = diag::warn_braces_around_scalar_init;
1025     break;
1026
1027   case InitializedEntity::EK_Member:
1028     // Warn on aggregate initialization but not on ctor init list or
1029     // default member initializer.
1030     if (Entity.getParent())
1031       DiagID = diag::warn_braces_around_scalar_init;
1032     break;
1033
1034   case InitializedEntity::EK_Variable:
1035   case InitializedEntity::EK_LambdaCapture:
1036     // No warning, might be direct-list-initialization.
1037     // FIXME: Should we warn for copy-list-initialization in these cases?
1038     break;
1039
1040   case InitializedEntity::EK_New:
1041   case InitializedEntity::EK_Temporary:
1042   case InitializedEntity::EK_CompoundLiteralInit:
1043     // No warning, braces are part of the syntax of the underlying construct.
1044     break;
1045
1046   case InitializedEntity::EK_RelatedResult:
1047     // No warning, we already warned when initializing the result.
1048     break;
1049
1050   case InitializedEntity::EK_Exception:
1051   case InitializedEntity::EK_Base:
1052   case InitializedEntity::EK_Delegating:
1053   case InitializedEntity::EK_BlockElement:
1054   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
1055   case InitializedEntity::EK_Binding:
1056   case InitializedEntity::EK_StmtExprResult:
1057     llvm_unreachable("unexpected braced scalar init");
1058   }
1059
1060   if (DiagID) {
1061     S.Diag(Braces.getBegin(), DiagID)
1062       << Braces
1063       << FixItHint::CreateRemoval(Braces.getBegin())
1064       << FixItHint::CreateRemoval(Braces.getEnd());
1065   }
1066 }
1067
1068 /// Check whether the initializer \p IList (that was written with explicit
1069 /// braces) can be used to initialize an object of type \p T.
1070 ///
1071 /// This also fills in \p StructuredList with the fully-braced, desugared
1072 /// form of the initialization.
1073 void InitListChecker::CheckExplicitInitList(const InitializedEntity &Entity,
1074                                             InitListExpr *IList, QualType &T,
1075                                             InitListExpr *StructuredList,
1076                                             bool TopLevelObject) {
1077   if (!VerifyOnly) {
1078     SyntacticToSemantic[IList] = StructuredList;
1079     StructuredList->setSyntacticForm(IList);
1080   }
1081
1082   unsigned Index = 0, StructuredIndex = 0;
1083   CheckListElementTypes(Entity, IList, T, /*SubobjectIsDesignatorContext=*/true,
1084                         Index, StructuredList, StructuredIndex, TopLevelObject);
1085   if (!VerifyOnly) {
1086     QualType ExprTy = T;
1087     if (!ExprTy->isArrayType())
1088       ExprTy = ExprTy.getNonLValueExprType(SemaRef.Context);
1089     IList->setType(ExprTy);
1090     StructuredList->setType(ExprTy);
1091   }
1092   if (hadError)
1093     return;
1094
1095   if (Index < IList->getNumInits()) {
1096     // We have leftover initializers
1097     if (VerifyOnly) {
1098       if (SemaRef.getLangOpts().CPlusPlus ||
1099           (SemaRef.getLangOpts().OpenCL &&
1100            IList->getType()->isVectorType())) {
1101         hadError = true;
1102       }
1103       return;
1104     }
1105
1106     if (StructuredIndex == 1 &&
1107         IsStringInit(StructuredList->getInit(0), T, SemaRef.Context) ==
1108             SIF_None) {
1109       unsigned DK = diag::ext_excess_initializers_in_char_array_initializer;
1110       if (SemaRef.getLangOpts().CPlusPlus) {
1111         DK = diag::err_excess_initializers_in_char_array_initializer;
1112         hadError = true;
1113       }
1114       // Special-case
1115       SemaRef.Diag(IList->getInit(Index)->getBeginLoc(), DK)
1116           << IList->getInit(Index)->getSourceRange();
1117     } else if (!T->isIncompleteType()) {
1118       // Don't complain for incomplete types, since we'll get an error
1119       // elsewhere
1120       QualType CurrentObjectType = StructuredList->getType();
1121       int initKind =
1122         CurrentObjectType->isArrayType()? 0 :
1123         CurrentObjectType->isVectorType()? 1 :
1124         CurrentObjectType->isScalarType()? 2 :
1125         CurrentObjectType->isUnionType()? 3 :
1126         4;
1127
1128       unsigned DK = diag::ext_excess_initializers;
1129       if (SemaRef.getLangOpts().CPlusPlus) {
1130         DK = diag::err_excess_initializers;
1131         hadError = true;
1132       }
1133       if (SemaRef.getLangOpts().OpenCL && initKind == 1) {
1134         DK = diag::err_excess_initializers;
1135         hadError = true;
1136       }
1137
1138       SemaRef.Diag(IList->getInit(Index)->getBeginLoc(), DK)
1139           << initKind << IList->getInit(Index)->getSourceRange();
1140     }
1141   }
1142
1143   if (!VerifyOnly) {
1144     if (T->isScalarType() && IList->getNumInits() == 1 &&
1145         !isa<InitListExpr>(IList->getInit(0)))
1146       warnBracedScalarInit(SemaRef, Entity, IList->getSourceRange());
1147
1148     // Warn if this is a class type that won't be an aggregate in future
1149     // versions of C++.
1150     auto *CXXRD = T->getAsCXXRecordDecl();
1151     if (CXXRD && CXXRD->hasUserDeclaredConstructor()) {
1152       // Don't warn if there's an equivalent default constructor that would be
1153       // used instead.
1154       bool HasEquivCtor = false;
1155       if (IList->getNumInits() == 0) {
1156         auto *CD = SemaRef.LookupDefaultConstructor(CXXRD);
1157         HasEquivCtor = CD && !CD->isDeleted();
1158       }
1159
1160       if (!HasEquivCtor) {
1161         SemaRef.Diag(IList->getBeginLoc(),
1162                      diag::warn_cxx2a_compat_aggregate_init_with_ctors)
1163             << IList->getSourceRange() << T;
1164       }
1165     }
1166   }
1167 }
1168
1169 void InitListChecker::CheckListElementTypes(const InitializedEntity &Entity,
1170                                             InitListExpr *IList,
1171                                             QualType &DeclType,
1172                                             bool SubobjectIsDesignatorContext,
1173                                             unsigned &Index,
1174                                             InitListExpr *StructuredList,
1175                                             unsigned &StructuredIndex,
1176                                             bool TopLevelObject) {
1177   if (DeclType->isAnyComplexType() && SubobjectIsDesignatorContext) {
1178     // Explicitly braced initializer for complex type can be real+imaginary
1179     // parts.
1180     CheckComplexType(Entity, IList, DeclType, Index,
1181                      StructuredList, StructuredIndex);
1182   } else if (DeclType->isScalarType()) {
1183     CheckScalarType(Entity, IList, DeclType, Index,
1184                     StructuredList, StructuredIndex);
1185   } else if (DeclType->isVectorType()) {
1186     CheckVectorType(Entity, IList, DeclType, Index,
1187                     StructuredList, StructuredIndex);
1188   } else if (DeclType->isRecordType()) {
1189     assert(DeclType->isAggregateType() &&
1190            "non-aggregate records should be handed in CheckSubElementType");
1191     RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
1192     auto Bases =
1193         CXXRecordDecl::base_class_range(CXXRecordDecl::base_class_iterator(),
1194                                         CXXRecordDecl::base_class_iterator());
1195     if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
1196       Bases = CXXRD->bases();
1197     CheckStructUnionTypes(Entity, IList, DeclType, Bases, RD->field_begin(),
1198                           SubobjectIsDesignatorContext, Index, StructuredList,
1199                           StructuredIndex, TopLevelObject);
1200   } else if (DeclType->isArrayType()) {
1201     llvm::APSInt Zero(
1202                     SemaRef.Context.getTypeSize(SemaRef.Context.getSizeType()),
1203                     false);
1204     CheckArrayType(Entity, IList, DeclType, Zero,
1205                    SubobjectIsDesignatorContext, Index,
1206                    StructuredList, StructuredIndex);
1207   } else if (DeclType->isVoidType() || DeclType->isFunctionType()) {
1208     // This type is invalid, issue a diagnostic.
1209     ++Index;
1210     if (!VerifyOnly)
1211       SemaRef.Diag(IList->getBeginLoc(), diag::err_illegal_initializer_type)
1212           << DeclType;
1213     hadError = true;
1214   } else if (DeclType->isReferenceType()) {
1215     CheckReferenceType(Entity, IList, DeclType, Index,
1216                        StructuredList, StructuredIndex);
1217   } else if (DeclType->isObjCObjectType()) {
1218     if (!VerifyOnly)
1219       SemaRef.Diag(IList->getBeginLoc(), diag::err_init_objc_class) << DeclType;
1220     hadError = true;
1221   } else if (DeclType->isOCLIntelSubgroupAVCType()) {
1222     // Checks for scalar type are sufficient for these types too.
1223     CheckScalarType(Entity, IList, DeclType, Index, StructuredList,
1224                     StructuredIndex);
1225   } else {
1226     if (!VerifyOnly)
1227       SemaRef.Diag(IList->getBeginLoc(), diag::err_illegal_initializer_type)
1228           << DeclType;
1229     hadError = true;
1230   }
1231 }
1232
1233 void InitListChecker::CheckSubElementType(const InitializedEntity &Entity,
1234                                           InitListExpr *IList,
1235                                           QualType ElemType,
1236                                           unsigned &Index,
1237                                           InitListExpr *StructuredList,
1238                                           unsigned &StructuredIndex) {
1239   Expr *expr = IList->getInit(Index);
1240
1241   if (ElemType->isReferenceType())
1242     return CheckReferenceType(Entity, IList, ElemType, Index,
1243                               StructuredList, StructuredIndex);
1244
1245   if (InitListExpr *SubInitList = dyn_cast<InitListExpr>(expr)) {
1246     if (SubInitList->getNumInits() == 1 &&
1247         IsStringInit(SubInitList->getInit(0), ElemType, SemaRef.Context) ==
1248         SIF_None) {
1249       expr = SubInitList->getInit(0);
1250     } else if (!SemaRef.getLangOpts().CPlusPlus) {
1251       InitListExpr *InnerStructuredList
1252         = getStructuredSubobjectInit(IList, Index, ElemType,
1253                                      StructuredList, StructuredIndex,
1254                                      SubInitList->getSourceRange(), true);
1255       CheckExplicitInitList(Entity, SubInitList, ElemType,
1256                             InnerStructuredList);
1257
1258       if (!hadError && !VerifyOnly) {
1259         bool RequiresSecondPass = false;
1260         FillInEmptyInitializations(Entity, InnerStructuredList,
1261                                    RequiresSecondPass, StructuredList,
1262                                    StructuredIndex);
1263         if (RequiresSecondPass && !hadError)
1264           FillInEmptyInitializations(Entity, InnerStructuredList,
1265                                      RequiresSecondPass, StructuredList,
1266                                      StructuredIndex);
1267       }
1268       ++StructuredIndex;
1269       ++Index;
1270       return;
1271     }
1272     // C++ initialization is handled later.
1273   } else if (isa<ImplicitValueInitExpr>(expr)) {
1274     // This happens during template instantiation when we see an InitListExpr
1275     // that we've already checked once.
1276     assert(SemaRef.Context.hasSameType(expr->getType(), ElemType) &&
1277            "found implicit initialization for the wrong type");
1278     if (!VerifyOnly)
1279       UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1280     ++Index;
1281     return;
1282   }
1283
1284   if (SemaRef.getLangOpts().CPlusPlus) {
1285     // C++ [dcl.init.aggr]p2:
1286     //   Each member is copy-initialized from the corresponding
1287     //   initializer-clause.
1288
1289     // FIXME: Better EqualLoc?
1290     InitializationKind Kind =
1291         InitializationKind::CreateCopy(expr->getBeginLoc(), SourceLocation());
1292
1293     // Vector elements can be initialized from other vectors in which case
1294     // we need initialization entity with a type of a vector (and not a vector
1295     // element!) initializing multiple vector elements.
1296     auto TmpEntity =
1297         (ElemType->isExtVectorType() && !Entity.getType()->isExtVectorType())
1298             ? InitializedEntity::InitializeTemporary(ElemType)
1299             : Entity;
1300
1301     InitializationSequence Seq(SemaRef, TmpEntity, Kind, expr,
1302                                /*TopLevelOfInitList*/ true);
1303
1304     // C++14 [dcl.init.aggr]p13:
1305     //   If the assignment-expression can initialize a member, the member is
1306     //   initialized. Otherwise [...] brace elision is assumed
1307     //
1308     // Brace elision is never performed if the element is not an
1309     // assignment-expression.
1310     if (Seq || isa<InitListExpr>(expr)) {
1311       if (!VerifyOnly) {
1312         ExprResult Result = Seq.Perform(SemaRef, TmpEntity, Kind, expr);
1313         if (Result.isInvalid())
1314           hadError = true;
1315
1316         UpdateStructuredListElement(StructuredList, StructuredIndex,
1317                                     Result.getAs<Expr>());
1318       } else if (!Seq)
1319         hadError = true;
1320       ++Index;
1321       return;
1322     }
1323
1324     // Fall through for subaggregate initialization
1325   } else if (ElemType->isScalarType() || ElemType->isAtomicType()) {
1326     // FIXME: Need to handle atomic aggregate types with implicit init lists.
1327     return CheckScalarType(Entity, IList, ElemType, Index,
1328                            StructuredList, StructuredIndex);
1329   } else if (const ArrayType *arrayType =
1330                  SemaRef.Context.getAsArrayType(ElemType)) {
1331     // arrayType can be incomplete if we're initializing a flexible
1332     // array member.  There's nothing we can do with the completed
1333     // type here, though.
1334
1335     if (IsStringInit(expr, arrayType, SemaRef.Context) == SIF_None) {
1336       if (!VerifyOnly) {
1337         CheckStringInit(expr, ElemType, arrayType, SemaRef);
1338         UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1339       }
1340       ++Index;
1341       return;
1342     }
1343
1344     // Fall through for subaggregate initialization.
1345
1346   } else {
1347     assert((ElemType->isRecordType() || ElemType->isVectorType() ||
1348             ElemType->isOpenCLSpecificType()) && "Unexpected type");
1349
1350     // C99 6.7.8p13:
1351     //
1352     //   The initializer for a structure or union object that has
1353     //   automatic storage duration shall be either an initializer
1354     //   list as described below, or a single expression that has
1355     //   compatible structure or union type. In the latter case, the
1356     //   initial value of the object, including unnamed members, is
1357     //   that of the expression.
1358     ExprResult ExprRes = expr;
1359     if (SemaRef.CheckSingleAssignmentConstraints(
1360             ElemType, ExprRes, !VerifyOnly) != Sema::Incompatible) {
1361       if (ExprRes.isInvalid())
1362         hadError = true;
1363       else {
1364         ExprRes = SemaRef.DefaultFunctionArrayLvalueConversion(ExprRes.get());
1365           if (ExprRes.isInvalid())
1366             hadError = true;
1367       }
1368       UpdateStructuredListElement(StructuredList, StructuredIndex,
1369                                   ExprRes.getAs<Expr>());
1370       ++Index;
1371       return;
1372     }
1373     ExprRes.get();
1374     // Fall through for subaggregate initialization
1375   }
1376
1377   // C++ [dcl.init.aggr]p12:
1378   //
1379   //   [...] Otherwise, if the member is itself a non-empty
1380   //   subaggregate, brace elision is assumed and the initializer is
1381   //   considered for the initialization of the first member of
1382   //   the subaggregate.
1383   // OpenCL vector initializer is handled elsewhere.
1384   if ((!SemaRef.getLangOpts().OpenCL && ElemType->isVectorType()) ||
1385       ElemType->isAggregateType()) {
1386     CheckImplicitInitList(Entity, IList, ElemType, Index, StructuredList,
1387                           StructuredIndex);
1388     ++StructuredIndex;
1389   } else {
1390     if (!VerifyOnly) {
1391       // We cannot initialize this element, so let
1392       // PerformCopyInitialization produce the appropriate diagnostic.
1393       SemaRef.PerformCopyInitialization(Entity, SourceLocation(), expr,
1394                                         /*TopLevelOfInitList=*/true);
1395     }
1396     hadError = true;
1397     ++Index;
1398     ++StructuredIndex;
1399   }
1400 }
1401
1402 void InitListChecker::CheckComplexType(const InitializedEntity &Entity,
1403                                        InitListExpr *IList, QualType DeclType,
1404                                        unsigned &Index,
1405                                        InitListExpr *StructuredList,
1406                                        unsigned &StructuredIndex) {
1407   assert(Index == 0 && "Index in explicit init list must be zero");
1408
1409   // As an extension, clang supports complex initializers, which initialize
1410   // a complex number component-wise.  When an explicit initializer list for
1411   // a complex number contains two two initializers, this extension kicks in:
1412   // it exepcts the initializer list to contain two elements convertible to
1413   // the element type of the complex type. The first element initializes
1414   // the real part, and the second element intitializes the imaginary part.
1415
1416   if (IList->getNumInits() != 2)
1417     return CheckScalarType(Entity, IList, DeclType, Index, StructuredList,
1418                            StructuredIndex);
1419
1420   // This is an extension in C.  (The builtin _Complex type does not exist
1421   // in the C++ standard.)
1422   if (!SemaRef.getLangOpts().CPlusPlus && !VerifyOnly)
1423     SemaRef.Diag(IList->getBeginLoc(), diag::ext_complex_component_init)
1424         << IList->getSourceRange();
1425
1426   // Initialize the complex number.
1427   QualType elementType = DeclType->getAs<ComplexType>()->getElementType();
1428   InitializedEntity ElementEntity =
1429     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1430
1431   for (unsigned i = 0; i < 2; ++i) {
1432     ElementEntity.setElementIndex(Index);
1433     CheckSubElementType(ElementEntity, IList, elementType, Index,
1434                         StructuredList, StructuredIndex);
1435   }
1436 }
1437
1438 void InitListChecker::CheckScalarType(const InitializedEntity &Entity,
1439                                       InitListExpr *IList, QualType DeclType,
1440                                       unsigned &Index,
1441                                       InitListExpr *StructuredList,
1442                                       unsigned &StructuredIndex) {
1443   if (Index >= IList->getNumInits()) {
1444     if (!VerifyOnly)
1445       SemaRef.Diag(IList->getBeginLoc(),
1446                    SemaRef.getLangOpts().CPlusPlus11
1447                        ? diag::warn_cxx98_compat_empty_scalar_initializer
1448                        : diag::err_empty_scalar_initializer)
1449           << IList->getSourceRange();
1450     hadError = !SemaRef.getLangOpts().CPlusPlus11;
1451     ++Index;
1452     ++StructuredIndex;
1453     return;
1454   }
1455
1456   Expr *expr = IList->getInit(Index);
1457   if (InitListExpr *SubIList = dyn_cast<InitListExpr>(expr)) {
1458     // FIXME: This is invalid, and accepting it causes overload resolution
1459     // to pick the wrong overload in some corner cases.
1460     if (!VerifyOnly)
1461       SemaRef.Diag(SubIList->getBeginLoc(),
1462                    diag::ext_many_braces_around_scalar_init)
1463           << SubIList->getSourceRange();
1464
1465     CheckScalarType(Entity, SubIList, DeclType, Index, StructuredList,
1466                     StructuredIndex);
1467     return;
1468   } else if (isa<DesignatedInitExpr>(expr)) {
1469     if (!VerifyOnly)
1470       SemaRef.Diag(expr->getBeginLoc(), diag::err_designator_for_scalar_init)
1471           << DeclType << expr->getSourceRange();
1472     hadError = true;
1473     ++Index;
1474     ++StructuredIndex;
1475     return;
1476   }
1477
1478   if (VerifyOnly) {
1479     if (!SemaRef.CanPerformCopyInitialization(Entity,expr))
1480       hadError = true;
1481     ++Index;
1482     return;
1483   }
1484
1485   ExprResult Result =
1486       SemaRef.PerformCopyInitialization(Entity, expr->getBeginLoc(), expr,
1487                                         /*TopLevelOfInitList=*/true);
1488
1489   Expr *ResultExpr = nullptr;
1490
1491   if (Result.isInvalid())
1492     hadError = true; // types weren't compatible.
1493   else {
1494     ResultExpr = Result.getAs<Expr>();
1495
1496     if (ResultExpr != expr) {
1497       // The type was promoted, update initializer list.
1498       IList->setInit(Index, ResultExpr);
1499     }
1500   }
1501   if (hadError)
1502     ++StructuredIndex;
1503   else
1504     UpdateStructuredListElement(StructuredList, StructuredIndex, ResultExpr);
1505   ++Index;
1506 }
1507
1508 void InitListChecker::CheckReferenceType(const InitializedEntity &Entity,
1509                                          InitListExpr *IList, QualType DeclType,
1510                                          unsigned &Index,
1511                                          InitListExpr *StructuredList,
1512                                          unsigned &StructuredIndex) {
1513   if (Index >= IList->getNumInits()) {
1514     // FIXME: It would be wonderful if we could point at the actual member. In
1515     // general, it would be useful to pass location information down the stack,
1516     // so that we know the location (or decl) of the "current object" being
1517     // initialized.
1518     if (!VerifyOnly)
1519       SemaRef.Diag(IList->getBeginLoc(),
1520                    diag::err_init_reference_member_uninitialized)
1521           << DeclType << IList->getSourceRange();
1522     hadError = true;
1523     ++Index;
1524     ++StructuredIndex;
1525     return;
1526   }
1527
1528   Expr *expr = IList->getInit(Index);
1529   if (isa<InitListExpr>(expr) && !SemaRef.getLangOpts().CPlusPlus11) {
1530     if (!VerifyOnly)
1531       SemaRef.Diag(IList->getBeginLoc(), diag::err_init_non_aggr_init_list)
1532           << DeclType << IList->getSourceRange();
1533     hadError = true;
1534     ++Index;
1535     ++StructuredIndex;
1536     return;
1537   }
1538
1539   if (VerifyOnly) {
1540     if (!SemaRef.CanPerformCopyInitialization(Entity,expr))
1541       hadError = true;
1542     ++Index;
1543     return;
1544   }
1545
1546   ExprResult Result =
1547       SemaRef.PerformCopyInitialization(Entity, expr->getBeginLoc(), expr,
1548                                         /*TopLevelOfInitList=*/true);
1549
1550   if (Result.isInvalid())
1551     hadError = true;
1552
1553   expr = Result.getAs<Expr>();
1554   IList->setInit(Index, expr);
1555
1556   if (hadError)
1557     ++StructuredIndex;
1558   else
1559     UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1560   ++Index;
1561 }
1562
1563 void InitListChecker::CheckVectorType(const InitializedEntity &Entity,
1564                                       InitListExpr *IList, QualType DeclType,
1565                                       unsigned &Index,
1566                                       InitListExpr *StructuredList,
1567                                       unsigned &StructuredIndex) {
1568   const VectorType *VT = DeclType->getAs<VectorType>();
1569   unsigned maxElements = VT->getNumElements();
1570   unsigned numEltsInit = 0;
1571   QualType elementType = VT->getElementType();
1572
1573   if (Index >= IList->getNumInits()) {
1574     // Make sure the element type can be value-initialized.
1575     if (VerifyOnly)
1576       CheckEmptyInitializable(
1577           InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity),
1578           IList->getEndLoc());
1579     return;
1580   }
1581
1582   if (!SemaRef.getLangOpts().OpenCL) {
1583     // If the initializing element is a vector, try to copy-initialize
1584     // instead of breaking it apart (which is doomed to failure anyway).
1585     Expr *Init = IList->getInit(Index);
1586     if (!isa<InitListExpr>(Init) && Init->getType()->isVectorType()) {
1587       if (VerifyOnly) {
1588         if (!SemaRef.CanPerformCopyInitialization(Entity, Init))
1589           hadError = true;
1590         ++Index;
1591         return;
1592       }
1593
1594       ExprResult Result =
1595           SemaRef.PerformCopyInitialization(Entity, Init->getBeginLoc(), Init,
1596                                             /*TopLevelOfInitList=*/true);
1597
1598       Expr *ResultExpr = nullptr;
1599       if (Result.isInvalid())
1600         hadError = true; // types weren't compatible.
1601       else {
1602         ResultExpr = Result.getAs<Expr>();
1603
1604         if (ResultExpr != Init) {
1605           // The type was promoted, update initializer list.
1606           IList->setInit(Index, ResultExpr);
1607         }
1608       }
1609       if (hadError)
1610         ++StructuredIndex;
1611       else
1612         UpdateStructuredListElement(StructuredList, StructuredIndex,
1613                                     ResultExpr);
1614       ++Index;
1615       return;
1616     }
1617
1618     InitializedEntity ElementEntity =
1619       InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1620
1621     for (unsigned i = 0; i < maxElements; ++i, ++numEltsInit) {
1622       // Don't attempt to go past the end of the init list
1623       if (Index >= IList->getNumInits()) {
1624         if (VerifyOnly)
1625           CheckEmptyInitializable(ElementEntity, IList->getEndLoc());
1626         break;
1627       }
1628
1629       ElementEntity.setElementIndex(Index);
1630       CheckSubElementType(ElementEntity, IList, elementType, Index,
1631                           StructuredList, StructuredIndex);
1632     }
1633
1634     if (VerifyOnly)
1635       return;
1636
1637     bool isBigEndian = SemaRef.Context.getTargetInfo().isBigEndian();
1638     const VectorType *T = Entity.getType()->getAs<VectorType>();
1639     if (isBigEndian && (T->getVectorKind() == VectorType::NeonVector ||
1640                         T->getVectorKind() == VectorType::NeonPolyVector)) {
1641       // The ability to use vector initializer lists is a GNU vector extension
1642       // and is unrelated to the NEON intrinsics in arm_neon.h. On little
1643       // endian machines it works fine, however on big endian machines it
1644       // exhibits surprising behaviour:
1645       //
1646       //   uint32x2_t x = {42, 64};
1647       //   return vget_lane_u32(x, 0); // Will return 64.
1648       //
1649       // Because of this, explicitly call out that it is non-portable.
1650       //
1651       SemaRef.Diag(IList->getBeginLoc(),
1652                    diag::warn_neon_vector_initializer_non_portable);
1653
1654       const char *typeCode;
1655       unsigned typeSize = SemaRef.Context.getTypeSize(elementType);
1656
1657       if (elementType->isFloatingType())
1658         typeCode = "f";
1659       else if (elementType->isSignedIntegerType())
1660         typeCode = "s";
1661       else if (elementType->isUnsignedIntegerType())
1662         typeCode = "u";
1663       else
1664         llvm_unreachable("Invalid element type!");
1665
1666       SemaRef.Diag(IList->getBeginLoc(),
1667                    SemaRef.Context.getTypeSize(VT) > 64
1668                        ? diag::note_neon_vector_initializer_non_portable_q
1669                        : diag::note_neon_vector_initializer_non_portable)
1670           << typeCode << typeSize;
1671     }
1672
1673     return;
1674   }
1675
1676   InitializedEntity ElementEntity =
1677     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1678
1679   // OpenCL initializers allows vectors to be constructed from vectors.
1680   for (unsigned i = 0; i < maxElements; ++i) {
1681     // Don't attempt to go past the end of the init list
1682     if (Index >= IList->getNumInits())
1683       break;
1684
1685     ElementEntity.setElementIndex(Index);
1686
1687     QualType IType = IList->getInit(Index)->getType();
1688     if (!IType->isVectorType()) {
1689       CheckSubElementType(ElementEntity, IList, elementType, Index,
1690                           StructuredList, StructuredIndex);
1691       ++numEltsInit;
1692     } else {
1693       QualType VecType;
1694       const VectorType *IVT = IType->getAs<VectorType>();
1695       unsigned numIElts = IVT->getNumElements();
1696
1697       if (IType->isExtVectorType())
1698         VecType = SemaRef.Context.getExtVectorType(elementType, numIElts);
1699       else
1700         VecType = SemaRef.Context.getVectorType(elementType, numIElts,
1701                                                 IVT->getVectorKind());
1702       CheckSubElementType(ElementEntity, IList, VecType, Index,
1703                           StructuredList, StructuredIndex);
1704       numEltsInit += numIElts;
1705     }
1706   }
1707
1708   // OpenCL requires all elements to be initialized.
1709   if (numEltsInit != maxElements) {
1710     if (!VerifyOnly)
1711       SemaRef.Diag(IList->getBeginLoc(),
1712                    diag::err_vector_incorrect_num_initializers)
1713           << (numEltsInit < maxElements) << maxElements << numEltsInit;
1714     hadError = true;
1715   }
1716 }
1717
1718 /// Check if the type of a class element has an accessible destructor, and marks
1719 /// it referenced. Returns true if we shouldn't form a reference to the
1720 /// destructor.
1721 ///
1722 /// Aggregate initialization requires a class element's destructor be
1723 /// accessible per 11.6.1 [dcl.init.aggr]:
1724 ///
1725 /// The destructor for each element of class type is potentially invoked
1726 /// (15.4 [class.dtor]) from the context where the aggregate initialization
1727 /// occurs.
1728 static bool checkDestructorReference(QualType ElementType, SourceLocation Loc,
1729                                      Sema &SemaRef) {
1730   auto *CXXRD = ElementType->getAsCXXRecordDecl();
1731   if (!CXXRD)
1732     return false;
1733
1734   CXXDestructorDecl *Destructor = SemaRef.LookupDestructor(CXXRD);
1735   SemaRef.CheckDestructorAccess(Loc, Destructor,
1736                                 SemaRef.PDiag(diag::err_access_dtor_temp)
1737                                 << ElementType);
1738   SemaRef.MarkFunctionReferenced(Loc, Destructor);
1739   return SemaRef.DiagnoseUseOfDecl(Destructor, Loc);
1740 }
1741
1742 void InitListChecker::CheckArrayType(const InitializedEntity &Entity,
1743                                      InitListExpr *IList, QualType &DeclType,
1744                                      llvm::APSInt elementIndex,
1745                                      bool SubobjectIsDesignatorContext,
1746                                      unsigned &Index,
1747                                      InitListExpr *StructuredList,
1748                                      unsigned &StructuredIndex) {
1749   const ArrayType *arrayType = SemaRef.Context.getAsArrayType(DeclType);
1750
1751   if (!VerifyOnly) {
1752     if (checkDestructorReference(arrayType->getElementType(),
1753                                  IList->getEndLoc(), SemaRef)) {
1754       hadError = true;
1755       return;
1756     }
1757   }
1758
1759   // Check for the special-case of initializing an array with a string.
1760   if (Index < IList->getNumInits()) {
1761     if (IsStringInit(IList->getInit(Index), arrayType, SemaRef.Context) ==
1762         SIF_None) {
1763       // We place the string literal directly into the resulting
1764       // initializer list. This is the only place where the structure
1765       // of the structured initializer list doesn't match exactly,
1766       // because doing so would involve allocating one character
1767       // constant for each string.
1768       if (!VerifyOnly) {
1769         CheckStringInit(IList->getInit(Index), DeclType, arrayType, SemaRef);
1770         UpdateStructuredListElement(StructuredList, StructuredIndex,
1771                                     IList->getInit(Index));
1772         StructuredList->resizeInits(SemaRef.Context, StructuredIndex);
1773       }
1774       ++Index;
1775       return;
1776     }
1777   }
1778   if (const VariableArrayType *VAT = dyn_cast<VariableArrayType>(arrayType)) {
1779     // Check for VLAs; in standard C it would be possible to check this
1780     // earlier, but I don't know where clang accepts VLAs (gcc accepts
1781     // them in all sorts of strange places).
1782     if (!VerifyOnly)
1783       SemaRef.Diag(VAT->getSizeExpr()->getBeginLoc(),
1784                    diag::err_variable_object_no_init)
1785           << VAT->getSizeExpr()->getSourceRange();
1786     hadError = true;
1787     ++Index;
1788     ++StructuredIndex;
1789     return;
1790   }
1791
1792   // We might know the maximum number of elements in advance.
1793   llvm::APSInt maxElements(elementIndex.getBitWidth(),
1794                            elementIndex.isUnsigned());
1795   bool maxElementsKnown = false;
1796   if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(arrayType)) {
1797     maxElements = CAT->getSize();
1798     elementIndex = elementIndex.extOrTrunc(maxElements.getBitWidth());
1799     elementIndex.setIsUnsigned(maxElements.isUnsigned());
1800     maxElementsKnown = true;
1801   }
1802
1803   QualType elementType = arrayType->getElementType();
1804   while (Index < IList->getNumInits()) {
1805     Expr *Init = IList->getInit(Index);
1806     if (DesignatedInitExpr *DIE = dyn_cast<DesignatedInitExpr>(Init)) {
1807       // If we're not the subobject that matches up with the '{' for
1808       // the designator, we shouldn't be handling the
1809       // designator. Return immediately.
1810       if (!SubobjectIsDesignatorContext)
1811         return;
1812
1813       // Handle this designated initializer. elementIndex will be
1814       // updated to be the next array element we'll initialize.
1815       if (CheckDesignatedInitializer(Entity, IList, DIE, 0,
1816                                      DeclType, nullptr, &elementIndex, Index,
1817                                      StructuredList, StructuredIndex, true,
1818                                      false)) {
1819         hadError = true;
1820         continue;
1821       }
1822
1823       if (elementIndex.getBitWidth() > maxElements.getBitWidth())
1824         maxElements = maxElements.extend(elementIndex.getBitWidth());
1825       else if (elementIndex.getBitWidth() < maxElements.getBitWidth())
1826         elementIndex = elementIndex.extend(maxElements.getBitWidth());
1827       elementIndex.setIsUnsigned(maxElements.isUnsigned());
1828
1829       // If the array is of incomplete type, keep track of the number of
1830       // elements in the initializer.
1831       if (!maxElementsKnown && elementIndex > maxElements)
1832         maxElements = elementIndex;
1833
1834       continue;
1835     }
1836
1837     // If we know the maximum number of elements, and we've already
1838     // hit it, stop consuming elements in the initializer list.
1839     if (maxElementsKnown && elementIndex == maxElements)
1840       break;
1841
1842     InitializedEntity ElementEntity =
1843       InitializedEntity::InitializeElement(SemaRef.Context, StructuredIndex,
1844                                            Entity);
1845     // Check this element.
1846     CheckSubElementType(ElementEntity, IList, elementType, Index,
1847                         StructuredList, StructuredIndex);
1848     ++elementIndex;
1849
1850     // If the array is of incomplete type, keep track of the number of
1851     // elements in the initializer.
1852     if (!maxElementsKnown && elementIndex > maxElements)
1853       maxElements = elementIndex;
1854   }
1855   if (!hadError && DeclType->isIncompleteArrayType() && !VerifyOnly) {
1856     // If this is an incomplete array type, the actual type needs to
1857     // be calculated here.
1858     llvm::APSInt Zero(maxElements.getBitWidth(), maxElements.isUnsigned());
1859     if (maxElements == Zero && !Entity.isVariableLengthArrayNew()) {
1860       // Sizing an array implicitly to zero is not allowed by ISO C,
1861       // but is supported by GNU.
1862       SemaRef.Diag(IList->getBeginLoc(), diag::ext_typecheck_zero_array_size);
1863     }
1864
1865     DeclType = SemaRef.Context.getConstantArrayType(elementType, maxElements,
1866                                                      ArrayType::Normal, 0);
1867   }
1868   if (!hadError && VerifyOnly) {
1869     // If there are any members of the array that get value-initialized, check
1870     // that is possible. That happens if we know the bound and don't have
1871     // enough elements, or if we're performing an array new with an unknown
1872     // bound.
1873     // FIXME: This needs to detect holes left by designated initializers too.
1874     if ((maxElementsKnown && elementIndex < maxElements) ||
1875         Entity.isVariableLengthArrayNew())
1876       CheckEmptyInitializable(
1877           InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity),
1878           IList->getEndLoc());
1879   }
1880 }
1881
1882 bool InitListChecker::CheckFlexibleArrayInit(const InitializedEntity &Entity,
1883                                              Expr *InitExpr,
1884                                              FieldDecl *Field,
1885                                              bool TopLevelObject) {
1886   // Handle GNU flexible array initializers.
1887   unsigned FlexArrayDiag;
1888   if (isa<InitListExpr>(InitExpr) &&
1889       cast<InitListExpr>(InitExpr)->getNumInits() == 0) {
1890     // Empty flexible array init always allowed as an extension
1891     FlexArrayDiag = diag::ext_flexible_array_init;
1892   } else if (SemaRef.getLangOpts().CPlusPlus) {
1893     // Disallow flexible array init in C++; it is not required for gcc
1894     // compatibility, and it needs work to IRGen correctly in general.
1895     FlexArrayDiag = diag::err_flexible_array_init;
1896   } else if (!TopLevelObject) {
1897     // Disallow flexible array init on non-top-level object
1898     FlexArrayDiag = diag::err_flexible_array_init;
1899   } else if (Entity.getKind() != InitializedEntity::EK_Variable) {
1900     // Disallow flexible array init on anything which is not a variable.
1901     FlexArrayDiag = diag::err_flexible_array_init;
1902   } else if (cast<VarDecl>(Entity.getDecl())->hasLocalStorage()) {
1903     // Disallow flexible array init on local variables.
1904     FlexArrayDiag = diag::err_flexible_array_init;
1905   } else {
1906     // Allow other cases.
1907     FlexArrayDiag = diag::ext_flexible_array_init;
1908   }
1909
1910   if (!VerifyOnly) {
1911     SemaRef.Diag(InitExpr->getBeginLoc(), FlexArrayDiag)
1912         << InitExpr->getBeginLoc();
1913     SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
1914       << Field;
1915   }
1916
1917   return FlexArrayDiag != diag::ext_flexible_array_init;
1918 }
1919
1920 void InitListChecker::CheckStructUnionTypes(
1921     const InitializedEntity &Entity, InitListExpr *IList, QualType DeclType,
1922     CXXRecordDecl::base_class_range Bases, RecordDecl::field_iterator Field,
1923     bool SubobjectIsDesignatorContext, unsigned &Index,
1924     InitListExpr *StructuredList, unsigned &StructuredIndex,
1925     bool TopLevelObject) {
1926   RecordDecl *structDecl = DeclType->getAs<RecordType>()->getDecl();
1927
1928   // If the record is invalid, some of it's members are invalid. To avoid
1929   // confusion, we forgo checking the intializer for the entire record.
1930   if (structDecl->isInvalidDecl()) {
1931     // Assume it was supposed to consume a single initializer.
1932     ++Index;
1933     hadError = true;
1934     return;
1935   }
1936
1937   if (DeclType->isUnionType() && IList->getNumInits() == 0) {
1938     RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
1939
1940     if (!VerifyOnly)
1941       for (FieldDecl *FD : RD->fields()) {
1942         QualType ET = SemaRef.Context.getBaseElementType(FD->getType());
1943         if (checkDestructorReference(ET, IList->getEndLoc(), SemaRef)) {
1944           hadError = true;
1945           return;
1946         }
1947       }
1948
1949     // If there's a default initializer, use it.
1950     if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->hasInClassInitializer()) {
1951       if (VerifyOnly)
1952         return;
1953       for (RecordDecl::field_iterator FieldEnd = RD->field_end();
1954            Field != FieldEnd; ++Field) {
1955         if (Field->hasInClassInitializer()) {
1956           StructuredList->setInitializedFieldInUnion(*Field);
1957           // FIXME: Actually build a CXXDefaultInitExpr?
1958           return;
1959         }
1960       }
1961     }
1962
1963     // Value-initialize the first member of the union that isn't an unnamed
1964     // bitfield.
1965     for (RecordDecl::field_iterator FieldEnd = RD->field_end();
1966          Field != FieldEnd; ++Field) {
1967       if (!Field->isUnnamedBitfield()) {
1968         if (VerifyOnly)
1969           CheckEmptyInitializable(
1970               InitializedEntity::InitializeMember(*Field, &Entity),
1971               IList->getEndLoc());
1972         else
1973           StructuredList->setInitializedFieldInUnion(*Field);
1974         break;
1975       }
1976     }
1977     return;
1978   }
1979
1980   bool InitializedSomething = false;
1981
1982   // If we have any base classes, they are initialized prior to the fields.
1983   for (auto &Base : Bases) {
1984     Expr *Init = Index < IList->getNumInits() ? IList->getInit(Index) : nullptr;
1985
1986     // Designated inits always initialize fields, so if we see one, all
1987     // remaining base classes have no explicit initializer.
1988     if (Init && isa<DesignatedInitExpr>(Init))
1989       Init = nullptr;
1990
1991     SourceLocation InitLoc = Init ? Init->getBeginLoc() : IList->getEndLoc();
1992     InitializedEntity BaseEntity = InitializedEntity::InitializeBase(
1993         SemaRef.Context, &Base, false, &Entity);
1994     if (Init) {
1995       CheckSubElementType(BaseEntity, IList, Base.getType(), Index,
1996                           StructuredList, StructuredIndex);
1997       InitializedSomething = true;
1998     } else if (VerifyOnly) {
1999       CheckEmptyInitializable(BaseEntity, InitLoc);
2000     }
2001
2002     if (!VerifyOnly)
2003       if (checkDestructorReference(Base.getType(), InitLoc, SemaRef)) {
2004         hadError = true;
2005         return;
2006       }
2007   }
2008
2009   // If structDecl is a forward declaration, this loop won't do
2010   // anything except look at designated initializers; That's okay,
2011   // because an error should get printed out elsewhere. It might be
2012   // worthwhile to skip over the rest of the initializer, though.
2013   RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
2014   RecordDecl::field_iterator FieldEnd = RD->field_end();
2015   bool CheckForMissingFields =
2016     !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts());
2017   bool HasDesignatedInit = false;
2018
2019   while (Index < IList->getNumInits()) {
2020     Expr *Init = IList->getInit(Index);
2021     SourceLocation InitLoc = Init->getBeginLoc();
2022
2023     if (DesignatedInitExpr *DIE = dyn_cast<DesignatedInitExpr>(Init)) {
2024       // If we're not the subobject that matches up with the '{' for
2025       // the designator, we shouldn't be handling the
2026       // designator. Return immediately.
2027       if (!SubobjectIsDesignatorContext)
2028         return;
2029
2030       HasDesignatedInit = true;
2031
2032       // Handle this designated initializer. Field will be updated to
2033       // the next field that we'll be initializing.
2034       if (CheckDesignatedInitializer(Entity, IList, DIE, 0,
2035                                      DeclType, &Field, nullptr, Index,
2036                                      StructuredList, StructuredIndex,
2037                                      true, TopLevelObject))
2038         hadError = true;
2039       else if (!VerifyOnly) {
2040         // Find the field named by the designated initializer.
2041         RecordDecl::field_iterator F = RD->field_begin();
2042         while (std::next(F) != Field)
2043           ++F;
2044         QualType ET = SemaRef.Context.getBaseElementType(F->getType());
2045         if (checkDestructorReference(ET, InitLoc, SemaRef)) {
2046           hadError = true;
2047           return;
2048         }
2049       }
2050
2051       InitializedSomething = true;
2052
2053       // Disable check for missing fields when designators are used.
2054       // This matches gcc behaviour.
2055       CheckForMissingFields = false;
2056       continue;
2057     }
2058
2059     if (Field == FieldEnd) {
2060       // We've run out of fields. We're done.
2061       break;
2062     }
2063
2064     // We've already initialized a member of a union. We're done.
2065     if (InitializedSomething && DeclType->isUnionType())
2066       break;
2067
2068     // If we've hit the flexible array member at the end, we're done.
2069     if (Field->getType()->isIncompleteArrayType())
2070       break;
2071
2072     if (Field->isUnnamedBitfield()) {
2073       // Don't initialize unnamed bitfields, e.g. "int : 20;"
2074       ++Field;
2075       continue;
2076     }
2077
2078     // Make sure we can use this declaration.
2079     bool InvalidUse;
2080     if (VerifyOnly)
2081       InvalidUse = !SemaRef.CanUseDecl(*Field, TreatUnavailableAsInvalid);
2082     else
2083       InvalidUse = SemaRef.DiagnoseUseOfDecl(
2084           *Field, IList->getInit(Index)->getBeginLoc());
2085     if (InvalidUse) {
2086       ++Index;
2087       ++Field;
2088       hadError = true;
2089       continue;
2090     }
2091
2092     if (!VerifyOnly) {
2093       QualType ET = SemaRef.Context.getBaseElementType(Field->getType());
2094       if (checkDestructorReference(ET, InitLoc, SemaRef)) {
2095         hadError = true;
2096         return;
2097       }
2098     }
2099
2100     InitializedEntity MemberEntity =
2101       InitializedEntity::InitializeMember(*Field, &Entity);
2102     CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
2103                         StructuredList, StructuredIndex);
2104     InitializedSomething = true;
2105
2106     if (DeclType->isUnionType() && !VerifyOnly) {
2107       // Initialize the first field within the union.
2108       StructuredList->setInitializedFieldInUnion(*Field);
2109     }
2110
2111     ++Field;
2112   }
2113
2114   // Emit warnings for missing struct field initializers.
2115   if (!VerifyOnly && InitializedSomething && CheckForMissingFields &&
2116       Field != FieldEnd && !Field->getType()->isIncompleteArrayType() &&
2117       !DeclType->isUnionType()) {
2118     // It is possible we have one or more unnamed bitfields remaining.
2119     // Find first (if any) named field and emit warning.
2120     for (RecordDecl::field_iterator it = Field, end = RD->field_end();
2121          it != end; ++it) {
2122       if (!it->isUnnamedBitfield() && !it->hasInClassInitializer()) {
2123         SemaRef.Diag(IList->getSourceRange().getEnd(),
2124                      diag::warn_missing_field_initializers) << *it;
2125         break;
2126       }
2127     }
2128   }
2129
2130   // Check that any remaining fields can be value-initialized.
2131   if (VerifyOnly && Field != FieldEnd && !DeclType->isUnionType() &&
2132       !Field->getType()->isIncompleteArrayType()) {
2133     // FIXME: Should check for holes left by designated initializers too.
2134     for (; Field != FieldEnd && !hadError; ++Field) {
2135       if (!Field->isUnnamedBitfield() && !Field->hasInClassInitializer())
2136         CheckEmptyInitializable(
2137             InitializedEntity::InitializeMember(*Field, &Entity),
2138             IList->getEndLoc());
2139     }
2140   }
2141
2142   // Check that the types of the remaining fields have accessible destructors.
2143   if (!VerifyOnly) {
2144     // If the initializer expression has a designated initializer, check the
2145     // elements for which a designated initializer is not provided too.
2146     RecordDecl::field_iterator I = HasDesignatedInit ? RD->field_begin()
2147                                                      : Field;
2148     for (RecordDecl::field_iterator E = RD->field_end(); I != E; ++I) {
2149       QualType ET = SemaRef.Context.getBaseElementType(I->getType());
2150       if (checkDestructorReference(ET, IList->getEndLoc(), SemaRef)) {
2151         hadError = true;
2152         return;
2153       }
2154     }
2155   }
2156
2157   if (Field == FieldEnd || !Field->getType()->isIncompleteArrayType() ||
2158       Index >= IList->getNumInits())
2159     return;
2160
2161   if (CheckFlexibleArrayInit(Entity, IList->getInit(Index), *Field,
2162                              TopLevelObject)) {
2163     hadError = true;
2164     ++Index;
2165     return;
2166   }
2167
2168   InitializedEntity MemberEntity =
2169     InitializedEntity::InitializeMember(*Field, &Entity);
2170
2171   if (isa<InitListExpr>(IList->getInit(Index)))
2172     CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
2173                         StructuredList, StructuredIndex);
2174   else
2175     CheckImplicitInitList(MemberEntity, IList, Field->getType(), Index,
2176                           StructuredList, StructuredIndex);
2177 }
2178
2179 /// Expand a field designator that refers to a member of an
2180 /// anonymous struct or union into a series of field designators that
2181 /// refers to the field within the appropriate subobject.
2182 ///
2183 static void ExpandAnonymousFieldDesignator(Sema &SemaRef,
2184                                            DesignatedInitExpr *DIE,
2185                                            unsigned DesigIdx,
2186                                            IndirectFieldDecl *IndirectField) {
2187   typedef DesignatedInitExpr::Designator Designator;
2188
2189   // Build the replacement designators.
2190   SmallVector<Designator, 4> Replacements;
2191   for (IndirectFieldDecl::chain_iterator PI = IndirectField->chain_begin(),
2192        PE = IndirectField->chain_end(); PI != PE; ++PI) {
2193     if (PI + 1 == PE)
2194       Replacements.push_back(Designator((IdentifierInfo *)nullptr,
2195                                     DIE->getDesignator(DesigIdx)->getDotLoc(),
2196                                 DIE->getDesignator(DesigIdx)->getFieldLoc()));
2197     else
2198       Replacements.push_back(Designator((IdentifierInfo *)nullptr,
2199                                         SourceLocation(), SourceLocation()));
2200     assert(isa<FieldDecl>(*PI));
2201     Replacements.back().setField(cast<FieldDecl>(*PI));
2202   }
2203
2204   // Expand the current designator into the set of replacement
2205   // designators, so we have a full subobject path down to where the
2206   // member of the anonymous struct/union is actually stored.
2207   DIE->ExpandDesignator(SemaRef.Context, DesigIdx, &Replacements[0],
2208                         &Replacements[0] + Replacements.size());
2209 }
2210
2211 static DesignatedInitExpr *CloneDesignatedInitExpr(Sema &SemaRef,
2212                                                    DesignatedInitExpr *DIE) {
2213   unsigned NumIndexExprs = DIE->getNumSubExprs() - 1;
2214   SmallVector<Expr*, 4> IndexExprs(NumIndexExprs);
2215   for (unsigned I = 0; I < NumIndexExprs; ++I)
2216     IndexExprs[I] = DIE->getSubExpr(I + 1);
2217   return DesignatedInitExpr::Create(SemaRef.Context, DIE->designators(),
2218                                     IndexExprs,
2219                                     DIE->getEqualOrColonLoc(),
2220                                     DIE->usesGNUSyntax(), DIE->getInit());
2221 }
2222
2223 namespace {
2224
2225 // Callback to only accept typo corrections that are for field members of
2226 // the given struct or union.
2227 class FieldInitializerValidatorCCC final : public CorrectionCandidateCallback {
2228  public:
2229   explicit FieldInitializerValidatorCCC(RecordDecl *RD)
2230       : Record(RD) {}
2231
2232   bool ValidateCandidate(const TypoCorrection &candidate) override {
2233     FieldDecl *FD = candidate.getCorrectionDeclAs<FieldDecl>();
2234     return FD && FD->getDeclContext()->getRedeclContext()->Equals(Record);
2235   }
2236
2237   std::unique_ptr<CorrectionCandidateCallback> clone() override {
2238     return llvm::make_unique<FieldInitializerValidatorCCC>(*this);
2239   }
2240
2241  private:
2242   RecordDecl *Record;
2243 };
2244
2245 } // end anonymous namespace
2246
2247 /// Check the well-formedness of a C99 designated initializer.
2248 ///
2249 /// Determines whether the designated initializer @p DIE, which
2250 /// resides at the given @p Index within the initializer list @p
2251 /// IList, is well-formed for a current object of type @p DeclType
2252 /// (C99 6.7.8). The actual subobject that this designator refers to
2253 /// within the current subobject is returned in either
2254 /// @p NextField or @p NextElementIndex (whichever is appropriate).
2255 ///
2256 /// @param IList  The initializer list in which this designated
2257 /// initializer occurs.
2258 ///
2259 /// @param DIE The designated initializer expression.
2260 ///
2261 /// @param DesigIdx  The index of the current designator.
2262 ///
2263 /// @param CurrentObjectType The type of the "current object" (C99 6.7.8p17),
2264 /// into which the designation in @p DIE should refer.
2265 ///
2266 /// @param NextField  If non-NULL and the first designator in @p DIE is
2267 /// a field, this will be set to the field declaration corresponding
2268 /// to the field named by the designator.
2269 ///
2270 /// @param NextElementIndex  If non-NULL and the first designator in @p
2271 /// DIE is an array designator or GNU array-range designator, this
2272 /// will be set to the last index initialized by this designator.
2273 ///
2274 /// @param Index  Index into @p IList where the designated initializer
2275 /// @p DIE occurs.
2276 ///
2277 /// @param StructuredList  The initializer list expression that
2278 /// describes all of the subobject initializers in the order they'll
2279 /// actually be initialized.
2280 ///
2281 /// @returns true if there was an error, false otherwise.
2282 bool
2283 InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
2284                                             InitListExpr *IList,
2285                                             DesignatedInitExpr *DIE,
2286                                             unsigned DesigIdx,
2287                                             QualType &CurrentObjectType,
2288                                           RecordDecl::field_iterator *NextField,
2289                                             llvm::APSInt *NextElementIndex,
2290                                             unsigned &Index,
2291                                             InitListExpr *StructuredList,
2292                                             unsigned &StructuredIndex,
2293                                             bool FinishSubobjectInit,
2294                                             bool TopLevelObject) {
2295   if (DesigIdx == DIE->size()) {
2296     // Check the actual initialization for the designated object type.
2297     bool prevHadError = hadError;
2298
2299     // Temporarily remove the designator expression from the
2300     // initializer list that the child calls see, so that we don't try
2301     // to re-process the designator.
2302     unsigned OldIndex = Index;
2303     IList->setInit(OldIndex, DIE->getInit());
2304
2305     CheckSubElementType(Entity, IList, CurrentObjectType, Index,
2306                         StructuredList, StructuredIndex);
2307
2308     // Restore the designated initializer expression in the syntactic
2309     // form of the initializer list.
2310     if (IList->getInit(OldIndex) != DIE->getInit())
2311       DIE->setInit(IList->getInit(OldIndex));
2312     IList->setInit(OldIndex, DIE);
2313
2314     return hadError && !prevHadError;
2315   }
2316
2317   DesignatedInitExpr::Designator *D = DIE->getDesignator(DesigIdx);
2318   bool IsFirstDesignator = (DesigIdx == 0);
2319   if (!VerifyOnly) {
2320     assert((IsFirstDesignator || StructuredList) &&
2321            "Need a non-designated initializer list to start from");
2322
2323     // Determine the structural initializer list that corresponds to the
2324     // current subobject.
2325     if (IsFirstDesignator)
2326       StructuredList = SyntacticToSemantic.lookup(IList);
2327     else {
2328       Expr *ExistingInit = StructuredIndex < StructuredList->getNumInits() ?
2329           StructuredList->getInit(StructuredIndex) : nullptr;
2330       if (!ExistingInit && StructuredList->hasArrayFiller())
2331         ExistingInit = StructuredList->getArrayFiller();
2332
2333       if (!ExistingInit)
2334         StructuredList = getStructuredSubobjectInit(
2335             IList, Index, CurrentObjectType, StructuredList, StructuredIndex,
2336             SourceRange(D->getBeginLoc(), DIE->getEndLoc()));
2337       else if (InitListExpr *Result = dyn_cast<InitListExpr>(ExistingInit))
2338         StructuredList = Result;
2339       else {
2340         if (DesignatedInitUpdateExpr *E =
2341                 dyn_cast<DesignatedInitUpdateExpr>(ExistingInit))
2342           StructuredList = E->getUpdater();
2343         else {
2344           DesignatedInitUpdateExpr *DIUE = new (SemaRef.Context)
2345               DesignatedInitUpdateExpr(SemaRef.Context, D->getBeginLoc(),
2346                                        ExistingInit, DIE->getEndLoc());
2347           StructuredList->updateInit(SemaRef.Context, StructuredIndex, DIUE);
2348           StructuredList = DIUE->getUpdater();
2349         }
2350
2351         // We need to check on source range validity because the previous
2352         // initializer does not have to be an explicit initializer. e.g.,
2353         //
2354         // struct P { int a, b; };
2355         // struct PP { struct P p } l = { { .a = 2 }, .p.b = 3 };
2356         //
2357         // There is an overwrite taking place because the first braced initializer
2358         // list "{ .a = 2 }" already provides value for .p.b (which is zero).
2359         if (ExistingInit->getSourceRange().isValid()) {
2360           // We are creating an initializer list that initializes the
2361           // subobjects of the current object, but there was already an
2362           // initialization that completely initialized the current
2363           // subobject, e.g., by a compound literal:
2364           //
2365           // struct X { int a, b; };
2366           // struct X xs[] = { [0] = (struct X) { 1, 2 }, [0].b = 3 };
2367           //
2368           // Here, xs[0].a == 0 and xs[0].b == 3, since the second,
2369           // designated initializer re-initializes the whole
2370           // subobject [0], overwriting previous initializers.
2371           SemaRef.Diag(D->getBeginLoc(),
2372                        diag::warn_subobject_initializer_overrides)
2373               << SourceRange(D->getBeginLoc(), DIE->getEndLoc());
2374
2375           SemaRef.Diag(ExistingInit->getBeginLoc(),
2376                        diag::note_previous_initializer)
2377               << /*FIXME:has side effects=*/0 << ExistingInit->getSourceRange();
2378         }
2379       }
2380     }
2381     assert(StructuredList && "Expected a structured initializer list");
2382   }
2383
2384   if (D->isFieldDesignator()) {
2385     // C99 6.7.8p7:
2386     //
2387     //   If a designator has the form
2388     //
2389     //      . identifier
2390     //
2391     //   then the current object (defined below) shall have
2392     //   structure or union type and the identifier shall be the
2393     //   name of a member of that type.
2394     const RecordType *RT = CurrentObjectType->getAs<RecordType>();
2395     if (!RT) {
2396       SourceLocation Loc = D->getDotLoc();
2397       if (Loc.isInvalid())
2398         Loc = D->getFieldLoc();
2399       if (!VerifyOnly)
2400         SemaRef.Diag(Loc, diag::err_field_designator_non_aggr)
2401           << SemaRef.getLangOpts().CPlusPlus << CurrentObjectType;
2402       ++Index;
2403       return true;
2404     }
2405
2406     FieldDecl *KnownField = D->getField();
2407     if (!KnownField) {
2408       IdentifierInfo *FieldName = D->getFieldName();
2409       DeclContext::lookup_result Lookup = RT->getDecl()->lookup(FieldName);
2410       for (NamedDecl *ND : Lookup) {
2411         if (auto *FD = dyn_cast<FieldDecl>(ND)) {
2412           KnownField = FD;
2413           break;
2414         }
2415         if (auto *IFD = dyn_cast<IndirectFieldDecl>(ND)) {
2416           // In verify mode, don't modify the original.
2417           if (VerifyOnly)
2418             DIE = CloneDesignatedInitExpr(SemaRef, DIE);
2419           ExpandAnonymousFieldDesignator(SemaRef, DIE, DesigIdx, IFD);
2420           D = DIE->getDesignator(DesigIdx);
2421           KnownField = cast<FieldDecl>(*IFD->chain_begin());
2422           break;
2423         }
2424       }
2425       if (!KnownField) {
2426         if (VerifyOnly) {
2427           ++Index;
2428           return true;  // No typo correction when just trying this out.
2429         }
2430
2431         // Name lookup found something, but it wasn't a field.
2432         if (!Lookup.empty()) {
2433           SemaRef.Diag(D->getFieldLoc(), diag::err_field_designator_nonfield)
2434             << FieldName;
2435           SemaRef.Diag(Lookup.front()->getLocation(),
2436                        diag::note_field_designator_found);
2437           ++Index;
2438           return true;
2439         }
2440
2441         // Name lookup didn't find anything.
2442         // Determine whether this was a typo for another field name.
2443         FieldInitializerValidatorCCC CCC(RT->getDecl());
2444         if (TypoCorrection Corrected = SemaRef.CorrectTypo(
2445                 DeclarationNameInfo(FieldName, D->getFieldLoc()),
2446                 Sema::LookupMemberName, /*Scope=*/nullptr, /*SS=*/nullptr, CCC,
2447                 Sema::CTK_ErrorRecovery, RT->getDecl())) {
2448           SemaRef.diagnoseTypo(
2449               Corrected,
2450               SemaRef.PDiag(diag::err_field_designator_unknown_suggest)
2451                 << FieldName << CurrentObjectType);
2452           KnownField = Corrected.getCorrectionDeclAs<FieldDecl>();
2453           hadError = true;
2454         } else {
2455           // Typo correction didn't find anything.
2456           SemaRef.Diag(D->getFieldLoc(), diag::err_field_designator_unknown)
2457             << FieldName << CurrentObjectType;
2458           ++Index;
2459           return true;
2460         }
2461       }
2462     }
2463
2464     unsigned FieldIndex = 0;
2465
2466     if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
2467       FieldIndex = CXXRD->getNumBases();
2468
2469     for (auto *FI : RT->getDecl()->fields()) {
2470       if (FI->isUnnamedBitfield())
2471         continue;
2472       if (declaresSameEntity(KnownField, FI)) {
2473         KnownField = FI;
2474         break;
2475       }
2476       ++FieldIndex;
2477     }
2478
2479     RecordDecl::field_iterator Field =
2480         RecordDecl::field_iterator(DeclContext::decl_iterator(KnownField));
2481
2482     // All of the fields of a union are located at the same place in
2483     // the initializer list.
2484     if (RT->getDecl()->isUnion()) {
2485       FieldIndex = 0;
2486       if (!VerifyOnly) {
2487         FieldDecl *CurrentField = StructuredList->getInitializedFieldInUnion();
2488         if (CurrentField && !declaresSameEntity(CurrentField, *Field)) {
2489           assert(StructuredList->getNumInits() == 1
2490                  && "A union should never have more than one initializer!");
2491
2492           Expr *ExistingInit = StructuredList->getInit(0);
2493           if (ExistingInit) {
2494             // We're about to throw away an initializer, emit warning.
2495             SemaRef.Diag(D->getFieldLoc(),
2496                          diag::warn_initializer_overrides)
2497               << D->getSourceRange();
2498             SemaRef.Diag(ExistingInit->getBeginLoc(),
2499                          diag::note_previous_initializer)
2500                 << /*FIXME:has side effects=*/0
2501                 << ExistingInit->getSourceRange();
2502           }
2503
2504           // remove existing initializer
2505           StructuredList->resizeInits(SemaRef.Context, 0);
2506           StructuredList->setInitializedFieldInUnion(nullptr);
2507         }
2508
2509         StructuredList->setInitializedFieldInUnion(*Field);
2510       }
2511     }
2512
2513     // Make sure we can use this declaration.
2514     bool InvalidUse;
2515     if (VerifyOnly)
2516       InvalidUse = !SemaRef.CanUseDecl(*Field, TreatUnavailableAsInvalid);
2517     else
2518       InvalidUse = SemaRef.DiagnoseUseOfDecl(*Field, D->getFieldLoc());
2519     if (InvalidUse) {
2520       ++Index;
2521       return true;
2522     }
2523
2524     if (!VerifyOnly) {
2525       // Update the designator with the field declaration.
2526       D->setField(*Field);
2527
2528       // Make sure that our non-designated initializer list has space
2529       // for a subobject corresponding to this field.
2530       if (FieldIndex >= StructuredList->getNumInits())
2531         StructuredList->resizeInits(SemaRef.Context, FieldIndex + 1);
2532     }
2533
2534     // This designator names a flexible array member.
2535     if (Field->getType()->isIncompleteArrayType()) {
2536       bool Invalid = false;
2537       if ((DesigIdx + 1) != DIE->size()) {
2538         // We can't designate an object within the flexible array
2539         // member (because GCC doesn't allow it).
2540         if (!VerifyOnly) {
2541           DesignatedInitExpr::Designator *NextD
2542             = DIE->getDesignator(DesigIdx + 1);
2543           SemaRef.Diag(NextD->getBeginLoc(),
2544                        diag::err_designator_into_flexible_array_member)
2545               << SourceRange(NextD->getBeginLoc(), DIE->getEndLoc());
2546           SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
2547             << *Field;
2548         }
2549         Invalid = true;
2550       }
2551
2552       if (!hadError && !isa<InitListExpr>(DIE->getInit()) &&
2553           !isa<StringLiteral>(DIE->getInit())) {
2554         // The initializer is not an initializer list.
2555         if (!VerifyOnly) {
2556           SemaRef.Diag(DIE->getInit()->getBeginLoc(),
2557                        diag::err_flexible_array_init_needs_braces)
2558               << DIE->getInit()->getSourceRange();
2559           SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
2560             << *Field;
2561         }
2562         Invalid = true;
2563       }
2564
2565       // Check GNU flexible array initializer.
2566       if (!Invalid && CheckFlexibleArrayInit(Entity, DIE->getInit(), *Field,
2567                                              TopLevelObject))
2568         Invalid = true;
2569
2570       if (Invalid) {
2571         ++Index;
2572         return true;
2573       }
2574
2575       // Initialize the array.
2576       bool prevHadError = hadError;
2577       unsigned newStructuredIndex = FieldIndex;
2578       unsigned OldIndex = Index;
2579       IList->setInit(Index, DIE->getInit());
2580
2581       InitializedEntity MemberEntity =
2582         InitializedEntity::InitializeMember(*Field, &Entity);
2583       CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
2584                           StructuredList, newStructuredIndex);
2585
2586       IList->setInit(OldIndex, DIE);
2587       if (hadError && !prevHadError) {
2588         ++Field;
2589         ++FieldIndex;
2590         if (NextField)
2591           *NextField = Field;
2592         StructuredIndex = FieldIndex;
2593         return true;
2594       }
2595     } else {
2596       // Recurse to check later designated subobjects.
2597       QualType FieldType = Field->getType();
2598       unsigned newStructuredIndex = FieldIndex;
2599
2600       InitializedEntity MemberEntity =
2601         InitializedEntity::InitializeMember(*Field, &Entity);
2602       if (CheckDesignatedInitializer(MemberEntity, IList, DIE, DesigIdx + 1,
2603                                      FieldType, nullptr, nullptr, Index,
2604                                      StructuredList, newStructuredIndex,
2605                                      FinishSubobjectInit, false))
2606         return true;
2607     }
2608
2609     // Find the position of the next field to be initialized in this
2610     // subobject.
2611     ++Field;
2612     ++FieldIndex;
2613
2614     // If this the first designator, our caller will continue checking
2615     // the rest of this struct/class/union subobject.
2616     if (IsFirstDesignator) {
2617       if (NextField)
2618         *NextField = Field;
2619       StructuredIndex = FieldIndex;
2620       return false;
2621     }
2622
2623     if (!FinishSubobjectInit)
2624       return false;
2625
2626     // We've already initialized something in the union; we're done.
2627     if (RT->getDecl()->isUnion())
2628       return hadError;
2629
2630     // Check the remaining fields within this class/struct/union subobject.
2631     bool prevHadError = hadError;
2632
2633     auto NoBases =
2634         CXXRecordDecl::base_class_range(CXXRecordDecl::base_class_iterator(),
2635                                         CXXRecordDecl::base_class_iterator());
2636     CheckStructUnionTypes(Entity, IList, CurrentObjectType, NoBases, Field,
2637                           false, Index, StructuredList, FieldIndex);
2638     return hadError && !prevHadError;
2639   }
2640
2641   // C99 6.7.8p6:
2642   //
2643   //   If a designator has the form
2644   //
2645   //      [ constant-expression ]
2646   //
2647   //   then the current object (defined below) shall have array
2648   //   type and the expression shall be an integer constant
2649   //   expression. If the array is of unknown size, any
2650   //   nonnegative value is valid.
2651   //
2652   // Additionally, cope with the GNU extension that permits
2653   // designators of the form
2654   //
2655   //      [ constant-expression ... constant-expression ]
2656   const ArrayType *AT = SemaRef.Context.getAsArrayType(CurrentObjectType);
2657   if (!AT) {
2658     if (!VerifyOnly)
2659       SemaRef.Diag(D->getLBracketLoc(), diag::err_array_designator_non_array)
2660         << CurrentObjectType;
2661     ++Index;
2662     return true;
2663   }
2664
2665   Expr *IndexExpr = nullptr;
2666   llvm::APSInt DesignatedStartIndex, DesignatedEndIndex;
2667   if (D->isArrayDesignator()) {
2668     IndexExpr = DIE->getArrayIndex(*D);
2669     DesignatedStartIndex = IndexExpr->EvaluateKnownConstInt(SemaRef.Context);
2670     DesignatedEndIndex = DesignatedStartIndex;
2671   } else {
2672     assert(D->isArrayRangeDesignator() && "Need array-range designator");
2673
2674     DesignatedStartIndex =
2675       DIE->getArrayRangeStart(*D)->EvaluateKnownConstInt(SemaRef.Context);
2676     DesignatedEndIndex =
2677       DIE->getArrayRangeEnd(*D)->EvaluateKnownConstInt(SemaRef.Context);
2678     IndexExpr = DIE->getArrayRangeEnd(*D);
2679
2680     // Codegen can't handle evaluating array range designators that have side
2681     // effects, because we replicate the AST value for each initialized element.
2682     // As such, set the sawArrayRangeDesignator() bit if we initialize multiple
2683     // elements with something that has a side effect, so codegen can emit an
2684     // "error unsupported" error instead of miscompiling the app.
2685     if (DesignatedStartIndex.getZExtValue()!=DesignatedEndIndex.getZExtValue()&&
2686         DIE->getInit()->HasSideEffects(SemaRef.Context) && !VerifyOnly)
2687       FullyStructuredList->sawArrayRangeDesignator();
2688   }
2689
2690   if (isa<ConstantArrayType>(AT)) {
2691     llvm::APSInt MaxElements(cast<ConstantArrayType>(AT)->getSize(), false);
2692     DesignatedStartIndex
2693       = DesignatedStartIndex.extOrTrunc(MaxElements.getBitWidth());
2694     DesignatedStartIndex.setIsUnsigned(MaxElements.isUnsigned());
2695     DesignatedEndIndex
2696       = DesignatedEndIndex.extOrTrunc(MaxElements.getBitWidth());
2697     DesignatedEndIndex.setIsUnsigned(MaxElements.isUnsigned());
2698     if (DesignatedEndIndex >= MaxElements) {
2699       if (!VerifyOnly)
2700         SemaRef.Diag(IndexExpr->getBeginLoc(),
2701                      diag::err_array_designator_too_large)
2702             << DesignatedEndIndex.toString(10) << MaxElements.toString(10)
2703             << IndexExpr->getSourceRange();
2704       ++Index;
2705       return true;
2706     }
2707   } else {
2708     unsigned DesignatedIndexBitWidth =
2709       ConstantArrayType::getMaxSizeBits(SemaRef.Context);
2710     DesignatedStartIndex =
2711       DesignatedStartIndex.extOrTrunc(DesignatedIndexBitWidth);
2712     DesignatedEndIndex =
2713       DesignatedEndIndex.extOrTrunc(DesignatedIndexBitWidth);
2714     DesignatedStartIndex.setIsUnsigned(true);
2715     DesignatedEndIndex.setIsUnsigned(true);
2716   }
2717
2718   if (!VerifyOnly && StructuredList->isStringLiteralInit()) {
2719     // We're modifying a string literal init; we have to decompose the string
2720     // so we can modify the individual characters.
2721     ASTContext &Context = SemaRef.Context;
2722     Expr *SubExpr = StructuredList->getInit(0)->IgnoreParens();
2723
2724     // Compute the character type
2725     QualType CharTy = AT->getElementType();
2726
2727     // Compute the type of the integer literals.
2728     QualType PromotedCharTy = CharTy;
2729     if (CharTy->isPromotableIntegerType())
2730       PromotedCharTy = Context.getPromotedIntegerType(CharTy);
2731     unsigned PromotedCharTyWidth = Context.getTypeSize(PromotedCharTy);
2732
2733     if (StringLiteral *SL = dyn_cast<StringLiteral>(SubExpr)) {
2734       // Get the length of the string.
2735       uint64_t StrLen = SL->getLength();
2736       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
2737         StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
2738       StructuredList->resizeInits(Context, StrLen);
2739
2740       // Build a literal for each character in the string, and put them into
2741       // the init list.
2742       for (unsigned i = 0, e = StrLen; i != e; ++i) {
2743         llvm::APInt CodeUnit(PromotedCharTyWidth, SL->getCodeUnit(i));
2744         Expr *Init = new (Context) IntegerLiteral(
2745             Context, CodeUnit, PromotedCharTy, SubExpr->getExprLoc());
2746         if (CharTy != PromotedCharTy)
2747           Init = ImplicitCastExpr::Create(Context, CharTy, CK_IntegralCast,
2748                                           Init, nullptr, VK_RValue);
2749         StructuredList->updateInit(Context, i, Init);
2750       }
2751     } else {
2752       ObjCEncodeExpr *E = cast<ObjCEncodeExpr>(SubExpr);
2753       std::string Str;
2754       Context.getObjCEncodingForType(E->getEncodedType(), Str);
2755
2756       // Get the length of the string.
2757       uint64_t StrLen = Str.size();
2758       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
2759         StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
2760       StructuredList->resizeInits(Context, StrLen);
2761
2762       // Build a literal for each character in the string, and put them into
2763       // the init list.
2764       for (unsigned i = 0, e = StrLen; i != e; ++i) {
2765         llvm::APInt CodeUnit(PromotedCharTyWidth, Str[i]);
2766         Expr *Init = new (Context) IntegerLiteral(
2767             Context, CodeUnit, PromotedCharTy, SubExpr->getExprLoc());
2768         if (CharTy != PromotedCharTy)
2769           Init = ImplicitCastExpr::Create(Context, CharTy, CK_IntegralCast,
2770                                           Init, nullptr, VK_RValue);
2771         StructuredList->updateInit(Context, i, Init);
2772       }
2773     }
2774   }
2775
2776   // Make sure that our non-designated initializer list has space
2777   // for a subobject corresponding to this array element.
2778   if (!VerifyOnly &&
2779       DesignatedEndIndex.getZExtValue() >= StructuredList->getNumInits())
2780     StructuredList->resizeInits(SemaRef.Context,
2781                                 DesignatedEndIndex.getZExtValue() + 1);
2782
2783   // Repeatedly perform subobject initializations in the range
2784   // [DesignatedStartIndex, DesignatedEndIndex].
2785
2786   // Move to the next designator
2787   unsigned ElementIndex = DesignatedStartIndex.getZExtValue();
2788   unsigned OldIndex = Index;
2789
2790   InitializedEntity ElementEntity =
2791     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
2792
2793   while (DesignatedStartIndex <= DesignatedEndIndex) {
2794     // Recurse to check later designated subobjects.
2795     QualType ElementType = AT->getElementType();
2796     Index = OldIndex;
2797
2798     ElementEntity.setElementIndex(ElementIndex);
2799     if (CheckDesignatedInitializer(
2800             ElementEntity, IList, DIE, DesigIdx + 1, ElementType, nullptr,
2801             nullptr, Index, StructuredList, ElementIndex,
2802             FinishSubobjectInit && (DesignatedStartIndex == DesignatedEndIndex),
2803             false))
2804       return true;
2805
2806     // Move to the next index in the array that we'll be initializing.
2807     ++DesignatedStartIndex;
2808     ElementIndex = DesignatedStartIndex.getZExtValue();
2809   }
2810
2811   // If this the first designator, our caller will continue checking
2812   // the rest of this array subobject.
2813   if (IsFirstDesignator) {
2814     if (NextElementIndex)
2815       *NextElementIndex = DesignatedStartIndex;
2816     StructuredIndex = ElementIndex;
2817     return false;
2818   }
2819
2820   if (!FinishSubobjectInit)
2821     return false;
2822
2823   // Check the remaining elements within this array subobject.
2824   bool prevHadError = hadError;
2825   CheckArrayType(Entity, IList, CurrentObjectType, DesignatedStartIndex,
2826                  /*SubobjectIsDesignatorContext=*/false, Index,
2827                  StructuredList, ElementIndex);
2828   return hadError && !prevHadError;
2829 }
2830
2831 // Get the structured initializer list for a subobject of type
2832 // @p CurrentObjectType.
2833 InitListExpr *
2834 InitListChecker::getStructuredSubobjectInit(InitListExpr *IList, unsigned Index,
2835                                             QualType CurrentObjectType,
2836                                             InitListExpr *StructuredList,
2837                                             unsigned StructuredIndex,
2838                                             SourceRange InitRange,
2839                                             bool IsFullyOverwritten) {
2840   if (VerifyOnly)
2841     return nullptr; // No structured list in verification-only mode.
2842   Expr *ExistingInit = nullptr;
2843   if (!StructuredList)
2844     ExistingInit = SyntacticToSemantic.lookup(IList);
2845   else if (StructuredIndex < StructuredList->getNumInits())
2846     ExistingInit = StructuredList->getInit(StructuredIndex);
2847
2848   if (InitListExpr *Result = dyn_cast_or_null<InitListExpr>(ExistingInit))
2849     // There might have already been initializers for subobjects of the current
2850     // object, but a subsequent initializer list will overwrite the entirety
2851     // of the current object. (See DR 253 and C99 6.7.8p21). e.g.,
2852     //
2853     // struct P { char x[6]; };
2854     // struct P l = { .x[2] = 'x', .x = { [0] = 'f' } };
2855     //
2856     // The first designated initializer is ignored, and l.x is just "f".
2857     if (!IsFullyOverwritten)
2858       return Result;
2859
2860   if (ExistingInit) {
2861     // We are creating an initializer list that initializes the
2862     // subobjects of the current object, but there was already an
2863     // initialization that completely initialized the current
2864     // subobject, e.g., by a compound literal:
2865     //
2866     // struct X { int a, b; };
2867     // struct X xs[] = { [0] = (struct X) { 1, 2 }, [0].b = 3 };
2868     //
2869     // Here, xs[0].a == 0 and xs[0].b == 3, since the second,
2870     // designated initializer re-initializes the whole
2871     // subobject [0], overwriting previous initializers.
2872     SemaRef.Diag(InitRange.getBegin(),
2873                  diag::warn_subobject_initializer_overrides)
2874       << InitRange;
2875     SemaRef.Diag(ExistingInit->getBeginLoc(), diag::note_previous_initializer)
2876         << /*FIXME:has side effects=*/0 << ExistingInit->getSourceRange();
2877   }
2878
2879   InitListExpr *Result
2880     = new (SemaRef.Context) InitListExpr(SemaRef.Context,
2881                                          InitRange.getBegin(), None,
2882                                          InitRange.getEnd());
2883
2884   QualType ResultType = CurrentObjectType;
2885   if (!ResultType->isArrayType())
2886     ResultType = ResultType.getNonLValueExprType(SemaRef.Context);
2887   Result->setType(ResultType);
2888
2889   // Pre-allocate storage for the structured initializer list.
2890   unsigned NumElements = 0;
2891   unsigned NumInits = 0;
2892   bool GotNumInits = false;
2893   if (!StructuredList) {
2894     NumInits = IList->getNumInits();
2895     GotNumInits = true;
2896   } else if (Index < IList->getNumInits()) {
2897     if (InitListExpr *SubList = dyn_cast<InitListExpr>(IList->getInit(Index))) {
2898       NumInits = SubList->getNumInits();
2899       GotNumInits = true;
2900     }
2901   }
2902
2903   if (const ArrayType *AType
2904       = SemaRef.Context.getAsArrayType(CurrentObjectType)) {
2905     if (const ConstantArrayType *CAType = dyn_cast<ConstantArrayType>(AType)) {
2906       NumElements = CAType->getSize().getZExtValue();
2907       // Simple heuristic so that we don't allocate a very large
2908       // initializer with many empty entries at the end.
2909       if (GotNumInits && NumElements > NumInits)
2910         NumElements = 0;
2911     }
2912   } else if (const VectorType *VType = CurrentObjectType->getAs<VectorType>())
2913     NumElements = VType->getNumElements();
2914   else if (const RecordType *RType = CurrentObjectType->getAs<RecordType>()) {
2915     RecordDecl *RDecl = RType->getDecl();
2916     if (RDecl->isUnion())
2917       NumElements = 1;
2918     else
2919       NumElements = std::distance(RDecl->field_begin(), RDecl->field_end());
2920   }
2921
2922   Result->reserveInits(SemaRef.Context, NumElements);
2923
2924   // Link this new initializer list into the structured initializer
2925   // lists.
2926   if (StructuredList)
2927     StructuredList->updateInit(SemaRef.Context, StructuredIndex, Result);
2928   else {
2929     Result->setSyntacticForm(IList);
2930     SyntacticToSemantic[IList] = Result;
2931   }
2932
2933   return Result;
2934 }
2935
2936 /// Update the initializer at index @p StructuredIndex within the
2937 /// structured initializer list to the value @p expr.
2938 void InitListChecker::UpdateStructuredListElement(InitListExpr *StructuredList,
2939                                                   unsigned &StructuredIndex,
2940                                                   Expr *expr) {
2941   // No structured initializer list to update
2942   if (!StructuredList)
2943     return;
2944
2945   if (Expr *PrevInit = StructuredList->updateInit(SemaRef.Context,
2946                                                   StructuredIndex, expr)) {
2947     // This initializer overwrites a previous initializer. Warn.
2948     // We need to check on source range validity because the previous
2949     // initializer does not have to be an explicit initializer.
2950     // struct P { int a, b; };
2951     // struct PP { struct P p } l = { { .a = 2 }, .p.b = 3 };
2952     // There is an overwrite taking place because the first braced initializer
2953     // list "{ .a = 2 }' already provides value for .p.b (which is zero).
2954     if (PrevInit->getSourceRange().isValid()) {
2955       SemaRef.Diag(expr->getBeginLoc(), diag::warn_initializer_overrides)
2956           << expr->getSourceRange();
2957
2958       SemaRef.Diag(PrevInit->getBeginLoc(), diag::note_previous_initializer)
2959           << /*FIXME:has side effects=*/0 << PrevInit->getSourceRange();
2960     }
2961   }
2962
2963   ++StructuredIndex;
2964 }
2965
2966 /// Check that the given Index expression is a valid array designator
2967 /// value. This is essentially just a wrapper around
2968 /// VerifyIntegerConstantExpression that also checks for negative values
2969 /// and produces a reasonable diagnostic if there is a
2970 /// failure. Returns the index expression, possibly with an implicit cast
2971 /// added, on success.  If everything went okay, Value will receive the
2972 /// value of the constant expression.
2973 static ExprResult
2974 CheckArrayDesignatorExpr(Sema &S, Expr *Index, llvm::APSInt &Value) {
2975   SourceLocation Loc = Index->getBeginLoc();
2976
2977   // Make sure this is an integer constant expression.
2978   ExprResult Result = S.VerifyIntegerConstantExpression(Index, &Value);
2979   if (Result.isInvalid())
2980     return Result;
2981
2982   if (Value.isSigned() && Value.isNegative())
2983     return S.Diag(Loc, diag::err_array_designator_negative)
2984       << Value.toString(10) << Index->getSourceRange();
2985
2986   Value.setIsUnsigned(true);
2987   return Result;
2988 }
2989
2990 ExprResult Sema::ActOnDesignatedInitializer(Designation &Desig,
2991                                             SourceLocation Loc,
2992                                             bool GNUSyntax,
2993                                             ExprResult Init) {
2994   typedef DesignatedInitExpr::Designator ASTDesignator;
2995
2996   bool Invalid = false;
2997   SmallVector<ASTDesignator, 32> Designators;
2998   SmallVector<Expr *, 32> InitExpressions;
2999
3000   // Build designators and check array designator expressions.
3001   for (unsigned Idx = 0; Idx < Desig.getNumDesignators(); ++Idx) {
3002     const Designator &D = Desig.getDesignator(Idx);
3003     switch (D.getKind()) {
3004     case Designator::FieldDesignator:
3005       Designators.push_back(ASTDesignator(D.getField(), D.getDotLoc(),
3006                                           D.getFieldLoc()));
3007       break;
3008
3009     case Designator::ArrayDesignator: {
3010       Expr *Index = static_cast<Expr *>(D.getArrayIndex());
3011       llvm::APSInt IndexValue;
3012       if (!Index->isTypeDependent() && !Index->isValueDependent())
3013         Index = CheckArrayDesignatorExpr(*this, Index, IndexValue).get();
3014       if (!Index)
3015         Invalid = true;
3016       else {
3017         Designators.push_back(ASTDesignator(InitExpressions.size(),
3018                                             D.getLBracketLoc(),
3019                                             D.getRBracketLoc()));
3020         InitExpressions.push_back(Index);
3021       }
3022       break;
3023     }
3024
3025     case Designator::ArrayRangeDesignator: {
3026       Expr *StartIndex = static_cast<Expr *>(D.getArrayRangeStart());
3027       Expr *EndIndex = static_cast<Expr *>(D.getArrayRangeEnd());
3028       llvm::APSInt StartValue;
3029       llvm::APSInt EndValue;
3030       bool StartDependent = StartIndex->isTypeDependent() ||
3031                             StartIndex->isValueDependent();
3032       bool EndDependent = EndIndex->isTypeDependent() ||
3033                           EndIndex->isValueDependent();
3034       if (!StartDependent)
3035         StartIndex =
3036             CheckArrayDesignatorExpr(*this, StartIndex, StartValue).get();
3037       if (!EndDependent)
3038         EndIndex = CheckArrayDesignatorExpr(*this, EndIndex, EndValue).get();
3039
3040       if (!StartIndex || !EndIndex)
3041         Invalid = true;
3042       else {
3043         // Make sure we're comparing values with the same bit width.
3044         if (StartDependent || EndDependent) {
3045           // Nothing to compute.
3046         } else if (StartValue.getBitWidth() > EndValue.getBitWidth())
3047           EndValue = EndValue.extend(StartValue.getBitWidth());
3048         else if (StartValue.getBitWidth() < EndValue.getBitWidth())
3049           StartValue = StartValue.extend(EndValue.getBitWidth());
3050
3051         if (!StartDependent && !EndDependent && EndValue < StartValue) {
3052           Diag(D.getEllipsisLoc(), diag::err_array_designator_empty_range)
3053             << StartValue.toString(10) << EndValue.toString(10)
3054             << StartIndex->getSourceRange() << EndIndex->getSourceRange();
3055           Invalid = true;
3056         } else {
3057           Designators.push_back(ASTDesignator(InitExpressions.size(),
3058                                               D.getLBracketLoc(),
3059                                               D.getEllipsisLoc(),
3060                                               D.getRBracketLoc()));
3061           InitExpressions.push_back(StartIndex);
3062           InitExpressions.push_back(EndIndex);
3063         }
3064       }
3065       break;
3066     }
3067     }
3068   }
3069
3070   if (Invalid || Init.isInvalid())
3071     return ExprError();
3072
3073   // Clear out the expressions within the designation.
3074   Desig.ClearExprs(*this);
3075
3076   DesignatedInitExpr *DIE
3077     = DesignatedInitExpr::Create(Context,
3078                                  Designators,
3079                                  InitExpressions, Loc, GNUSyntax,
3080                                  Init.getAs<Expr>());
3081
3082   if (!getLangOpts().C99)
3083     Diag(DIE->getBeginLoc(), diag::ext_designated_init)
3084         << DIE->getSourceRange();
3085
3086   return DIE;
3087 }
3088
3089 //===----------------------------------------------------------------------===//
3090 // Initialization entity
3091 //===----------------------------------------------------------------------===//
3092
3093 InitializedEntity::InitializedEntity(ASTContext &Context, unsigned Index,
3094                                      const InitializedEntity &Parent)
3095   : Parent(&Parent), Index(Index)
3096 {
3097   if (const ArrayType *AT = Context.getAsArrayType(Parent.getType())) {
3098     Kind = EK_ArrayElement;
3099     Type = AT->getElementType();
3100   } else if (const VectorType *VT = Parent.getType()->getAs<VectorType>()) {
3101     Kind = EK_VectorElement;
3102     Type = VT->getElementType();
3103   } else {
3104     const ComplexType *CT = Parent.getType()->getAs<ComplexType>();
3105     assert(CT && "Unexpected type");
3106     Kind = EK_ComplexElement;
3107     Type = CT->getElementType();
3108   }
3109 }
3110
3111 InitializedEntity
3112 InitializedEntity::InitializeBase(ASTContext &Context,
3113                                   const CXXBaseSpecifier *Base,
3114                                   bool IsInheritedVirtualBase,
3115                                   const InitializedEntity *Parent) {
3116   InitializedEntity Result;
3117   Result.Kind = EK_Base;
3118   Result.Parent = Parent;
3119   Result.Base = reinterpret_cast<uintptr_t>(Base);
3120   if (IsInheritedVirtualBase)
3121     Result.Base |= 0x01;
3122
3123   Result.Type = Base->getType();
3124   return Result;
3125 }
3126
3127 DeclarationName InitializedEntity::getName() const {
3128   switch (getKind()) {
3129   case EK_Parameter:
3130   case EK_Parameter_CF_Audited: {
3131     ParmVarDecl *D = reinterpret_cast<ParmVarDecl*>(Parameter & ~0x1);
3132     return (D ? D->getDeclName() : DeclarationName());
3133   }
3134
3135   case EK_Variable:
3136   case EK_Member:
3137   case EK_Binding:
3138     return Variable.VariableOrMember->getDeclName();
3139
3140   case EK_LambdaCapture:
3141     return DeclarationName(Capture.VarID);
3142
3143   case EK_Result:
3144   case EK_StmtExprResult:
3145   case EK_Exception:
3146   case EK_New:
3147   case EK_Temporary:
3148   case EK_Base:
3149   case EK_Delegating:
3150   case EK_ArrayElement:
3151   case EK_VectorElement:
3152   case EK_ComplexElement:
3153   case EK_BlockElement:
3154   case EK_LambdaToBlockConversionBlockElement:
3155   case EK_CompoundLiteralInit:
3156   case EK_RelatedResult:
3157     return DeclarationName();
3158   }
3159
3160   llvm_unreachable("Invalid EntityKind!");
3161 }
3162
3163 ValueDecl *InitializedEntity::getDecl() const {
3164   switch (getKind()) {
3165   case EK_Variable:
3166   case EK_Member:
3167   case EK_Binding:
3168     return Variable.VariableOrMember;
3169
3170   case EK_Parameter:
3171   case EK_Parameter_CF_Audited:
3172     return reinterpret_cast<ParmVarDecl*>(Parameter & ~0x1);
3173
3174   case EK_Result:
3175   case EK_StmtExprResult:
3176   case EK_Exception:
3177   case EK_New:
3178   case EK_Temporary:
3179   case EK_Base:
3180   case EK_Delegating:
3181   case EK_ArrayElement:
3182   case EK_VectorElement:
3183   case EK_ComplexElement:
3184   case EK_BlockElement:
3185   case EK_LambdaToBlockConversionBlockElement:
3186   case EK_LambdaCapture:
3187   case EK_CompoundLiteralInit:
3188   case EK_RelatedResult:
3189     return nullptr;
3190   }
3191
3192   llvm_unreachable("Invalid EntityKind!");
3193 }
3194
3195 bool InitializedEntity::allowsNRVO() const {
3196   switch (getKind()) {
3197   case EK_Result:
3198   case EK_Exception:
3199     return LocAndNRVO.NRVO;
3200
3201   case EK_StmtExprResult:
3202   case EK_Variable:
3203   case EK_Parameter:
3204   case EK_Parameter_CF_Audited:
3205   case EK_Member:
3206   case EK_Binding:
3207   case EK_New:
3208   case EK_Temporary:
3209   case EK_CompoundLiteralInit:
3210   case EK_Base:
3211   case EK_Delegating:
3212   case EK_ArrayElement:
3213   case EK_VectorElement:
3214   case EK_ComplexElement:
3215   case EK_BlockElement:
3216   case EK_LambdaToBlockConversionBlockElement:
3217   case EK_LambdaCapture:
3218   case EK_RelatedResult:
3219     break;
3220   }
3221
3222   return false;
3223 }
3224
3225 unsigned InitializedEntity::dumpImpl(raw_ostream &OS) const {
3226   assert(getParent() != this);
3227   unsigned Depth = getParent() ? getParent()->dumpImpl(OS) : 0;
3228   for (unsigned I = 0; I != Depth; ++I)
3229     OS << "`-";
3230
3231   switch (getKind()) {
3232   case EK_Variable: OS << "Variable"; break;
3233   case EK_Parameter: OS << "Parameter"; break;
3234   case EK_Parameter_CF_Audited: OS << "CF audited function Parameter";
3235     break;
3236   case EK_Result: OS << "Result"; break;
3237   case EK_StmtExprResult: OS << "StmtExprResult"; break;
3238   case EK_Exception: OS << "Exception"; break;
3239   case EK_Member: OS << "Member"; break;
3240   case EK_Binding: OS << "Binding"; break;
3241   case EK_New: OS << "New"; break;
3242   case EK_Temporary: OS << "Temporary"; break;
3243   case EK_CompoundLiteralInit: OS << "CompoundLiteral";break;
3244   case EK_RelatedResult: OS << "RelatedResult"; break;
3245   case EK_Base: OS << "Base"; break;
3246   case EK_Delegating: OS << "Delegating"; break;
3247   case EK_ArrayElement: OS << "ArrayElement " << Index; break;
3248   case EK_VectorElement: OS << "VectorElement " << Index; break;
3249   case EK_ComplexElement: OS << "ComplexElement " << Index; break;
3250   case EK_BlockElement: OS << "Block"; break;
3251   case EK_LambdaToBlockConversionBlockElement:
3252     OS << "Block (lambda)";
3253     break;
3254   case EK_LambdaCapture:
3255     OS << "LambdaCapture ";
3256     OS << DeclarationName(Capture.VarID);
3257     break;
3258   }
3259
3260   if (auto *D = getDecl()) {
3261     OS << " ";
3262     D->printQualifiedName(OS);
3263   }
3264
3265   OS << " '" << getType().getAsString() << "'\n";
3266
3267   return Depth + 1;
3268 }
3269
3270 LLVM_DUMP_METHOD void InitializedEntity::dump() const {
3271   dumpImpl(llvm::errs());
3272 }
3273
3274 //===----------------------------------------------------------------------===//
3275 // Initialization sequence
3276 //===----------------------------------------------------------------------===//
3277
3278 void InitializationSequence::Step::Destroy() {
3279   switch (Kind) {
3280   case SK_ResolveAddressOfOverloadedFunction:
3281   case SK_CastDerivedToBaseRValue:
3282   case SK_CastDerivedToBaseXValue:
3283   case SK_CastDerivedToBaseLValue:
3284   case SK_BindReference:
3285   case SK_BindReferenceToTemporary:
3286   case SK_FinalCopy:
3287   case SK_ExtraneousCopyToTemporary:
3288   case SK_UserConversion:
3289   case SK_QualificationConversionRValue:
3290   case SK_QualificationConversionXValue:
3291   case SK_QualificationConversionLValue:
3292   case SK_AtomicConversion:
3293   case SK_ListInitialization:
3294   case SK_UnwrapInitList:
3295   case SK_RewrapInitList:
3296   case SK_ConstructorInitialization:
3297   case SK_ConstructorInitializationFromList:
3298   case SK_ZeroInitialization:
3299   case SK_CAssignment:
3300   case SK_StringInit:
3301   case SK_ObjCObjectConversion:
3302   case SK_ArrayLoopIndex:
3303   case SK_ArrayLoopInit:
3304   case SK_ArrayInit:
3305   case SK_GNUArrayInit:
3306   case SK_ParenthesizedArrayInit:
3307   case SK_PassByIndirectCopyRestore:
3308   case SK_PassByIndirectRestore:
3309   case SK_ProduceObjCObject:
3310   case SK_StdInitializerList:
3311   case SK_StdInitializerListConstructorCall:
3312   case SK_OCLSamplerInit:
3313   case SK_OCLZeroOpaqueType:
3314     break;
3315
3316   case SK_ConversionSequence:
3317   case SK_ConversionSequenceNoNarrowing:
3318     delete ICS;
3319   }
3320 }
3321
3322 bool InitializationSequence::isDirectReferenceBinding() const {
3323   // There can be some lvalue adjustments after the SK_BindReference step.
3324   for (auto I = Steps.rbegin(); I != Steps.rend(); ++I) {
3325     if (I->Kind == SK_BindReference)
3326       return true;
3327     if (I->Kind == SK_BindReferenceToTemporary)
3328       return false;
3329   }
3330   return false;
3331 }
3332
3333 bool InitializationSequence::isAmbiguous() const {
3334   if (!Failed())
3335     return false;
3336
3337   switch (getFailureKind()) {
3338   case FK_TooManyInitsForReference:
3339   case FK_ParenthesizedListInitForReference:
3340   case FK_ArrayNeedsInitList:
3341   case FK_ArrayNeedsInitListOrStringLiteral:
3342   case FK_ArrayNeedsInitListOrWideStringLiteral:
3343   case FK_NarrowStringIntoWideCharArray:
3344   case FK_WideStringIntoCharArray:
3345   case FK_IncompatWideStringIntoWideChar:
3346   case FK_PlainStringIntoUTF8Char:
3347   case FK_UTF8StringIntoPlainChar:
3348   case FK_AddressOfOverloadFailed: // FIXME: Could do better
3349   case FK_NonConstLValueReferenceBindingToTemporary:
3350   case FK_NonConstLValueReferenceBindingToBitfield:
3351   case FK_NonConstLValueReferenceBindingToVectorElement:
3352   case FK_NonConstLValueReferenceBindingToUnrelated:
3353   case FK_RValueReferenceBindingToLValue:
3354   case FK_ReferenceAddrspaceMismatchTemporary:
3355   case FK_ReferenceInitDropsQualifiers:
3356   case FK_ReferenceInitFailed:
3357   case FK_ConversionFailed:
3358   case FK_ConversionFromPropertyFailed:
3359   case FK_TooManyInitsForScalar:
3360   case FK_ParenthesizedListInitForScalar:
3361   case FK_ReferenceBindingToInitList:
3362   case FK_InitListBadDestinationType:
3363   case FK_DefaultInitOfConst:
3364   case FK_Incomplete:
3365   case FK_ArrayTypeMismatch:
3366   case FK_NonConstantArrayInit:
3367   case FK_ListInitializationFailed:
3368   case FK_VariableLengthArrayHasInitializer:
3369   case FK_PlaceholderType:
3370   case FK_ExplicitConstructor:
3371   case FK_AddressOfUnaddressableFunction:
3372     return false;
3373
3374   case FK_ReferenceInitOverloadFailed:
3375   case FK_UserConversionOverloadFailed:
3376   case FK_ConstructorOverloadFailed:
3377   case FK_ListConstructorOverloadFailed:
3378     return FailedOverloadResult == OR_Ambiguous;
3379   }
3380
3381   llvm_unreachable("Invalid EntityKind!");
3382 }
3383
3384 bool InitializationSequence::isConstructorInitialization() const {
3385   return !Steps.empty() && Steps.back().Kind == SK_ConstructorInitialization;
3386 }
3387
3388 void
3389 InitializationSequence
3390 ::AddAddressOverloadResolutionStep(FunctionDecl *Function,
3391                                    DeclAccessPair Found,
3392                                    bool HadMultipleCandidates) {
3393   Step S;
3394   S.Kind = SK_ResolveAddressOfOverloadedFunction;
3395   S.Type = Function->getType();
3396   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3397   S.Function.Function = Function;
3398   S.Function.FoundDecl = Found;
3399   Steps.push_back(S);
3400 }
3401
3402 void InitializationSequence::AddDerivedToBaseCastStep(QualType BaseType,
3403                                                       ExprValueKind VK) {
3404   Step S;
3405   switch (VK) {
3406   case VK_RValue: S.Kind = SK_CastDerivedToBaseRValue; break;
3407   case VK_XValue: S.Kind = SK_CastDerivedToBaseXValue; break;
3408   case VK_LValue: S.Kind = SK_CastDerivedToBaseLValue; break;
3409   }
3410   S.Type = BaseType;
3411   Steps.push_back(S);
3412 }
3413
3414 void InitializationSequence::AddReferenceBindingStep(QualType T,
3415                                                      bool BindingTemporary) {
3416   Step S;
3417   S.Kind = BindingTemporary? SK_BindReferenceToTemporary : SK_BindReference;
3418   S.Type = T;
3419   Steps.push_back(S);
3420 }
3421
3422 void InitializationSequence::AddFinalCopy(QualType T) {
3423   Step S;
3424   S.Kind = SK_FinalCopy;
3425   S.Type = T;
3426   Steps.push_back(S);
3427 }
3428
3429 void InitializationSequence::AddExtraneousCopyToTemporary(QualType T) {
3430   Step S;
3431   S.Kind = SK_ExtraneousCopyToTemporary;
3432   S.Type = T;
3433   Steps.push_back(S);
3434 }
3435
3436 void
3437 InitializationSequence::AddUserConversionStep(FunctionDecl *Function,
3438                                               DeclAccessPair FoundDecl,
3439                                               QualType T,
3440                                               bool HadMultipleCandidates) {
3441   Step S;
3442   S.Kind = SK_UserConversion;
3443   S.Type = T;
3444   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3445   S.Function.Function = Function;
3446   S.Function.FoundDecl = FoundDecl;
3447   Steps.push_back(S);
3448 }
3449
3450 void InitializationSequence::AddQualificationConversionStep(QualType Ty,
3451                                                             ExprValueKind VK) {
3452   Step S;
3453   S.Kind = SK_QualificationConversionRValue; // work around a gcc warning
3454   switch (VK) {
3455   case VK_RValue:
3456     S.Kind = SK_QualificationConversionRValue;
3457     break;
3458   case VK_XValue:
3459     S.Kind = SK_QualificationConversionXValue;
3460     break;
3461   case VK_LValue:
3462     S.Kind = SK_QualificationConversionLValue;
3463     break;
3464   }
3465   S.Type = Ty;
3466   Steps.push_back(S);
3467 }
3468
3469 void InitializationSequence::AddAtomicConversionStep(QualType Ty) {
3470   Step S;
3471   S.Kind = SK_AtomicConversion;
3472   S.Type = Ty;
3473   Steps.push_back(S);
3474 }
3475
3476 void InitializationSequence::AddConversionSequenceStep(
3477     const ImplicitConversionSequence &ICS, QualType T,
3478     bool TopLevelOfInitList) {
3479   Step S;
3480   S.Kind = TopLevelOfInitList ? SK_ConversionSequenceNoNarrowing
3481                               : SK_ConversionSequence;
3482   S.Type = T;
3483   S.ICS = new ImplicitConversionSequence(ICS);
3484   Steps.push_back(S);
3485 }
3486
3487 void InitializationSequence::AddListInitializationStep(QualType T) {
3488   Step S;
3489   S.Kind = SK_ListInitialization;
3490   S.Type = T;
3491   Steps.push_back(S);
3492 }
3493
3494 void InitializationSequence::AddConstructorInitializationStep(
3495     DeclAccessPair FoundDecl, CXXConstructorDecl *Constructor, QualType T,
3496     bool HadMultipleCandidates, bool FromInitList, bool AsInitList) {
3497   Step S;
3498   S.Kind = FromInitList ? AsInitList ? SK_StdInitializerListConstructorCall
3499                                      : SK_ConstructorInitializationFromList
3500                         : SK_ConstructorInitialization;
3501   S.Type = T;
3502   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3503   S.Function.Function = Constructor;
3504   S.Function.FoundDecl = FoundDecl;
3505   Steps.push_back(S);
3506 }
3507
3508 void InitializationSequence::AddZeroInitializationStep(QualType T) {
3509   Step S;
3510   S.Kind = SK_ZeroInitialization;
3511   S.Type = T;
3512   Steps.push_back(S);
3513 }
3514
3515 void InitializationSequence::AddCAssignmentStep(QualType T) {
3516   Step S;
3517   S.Kind = SK_CAssignment;
3518   S.Type = T;
3519   Steps.push_back(S);
3520 }
3521
3522 void InitializationSequence::AddStringInitStep(QualType T) {
3523   Step S;
3524   S.Kind = SK_StringInit;
3525   S.Type = T;
3526   Steps.push_back(S);
3527 }
3528
3529 void InitializationSequence::AddObjCObjectConversionStep(QualType T) {
3530   Step S;
3531   S.Kind = SK_ObjCObjectConversion;
3532   S.Type = T;
3533   Steps.push_back(S);
3534 }
3535
3536 void InitializationSequence::AddArrayInitStep(QualType T, bool IsGNUExtension) {
3537   Step S;
3538   S.Kind = IsGNUExtension ? SK_GNUArrayInit : SK_ArrayInit;
3539   S.Type = T;
3540   Steps.push_back(S);
3541 }
3542
3543 void InitializationSequence::AddArrayInitLoopStep(QualType T, QualType EltT) {
3544   Step S;
3545   S.Kind = SK_ArrayLoopIndex;
3546   S.Type = EltT;
3547   Steps.insert(Steps.begin(), S);
3548
3549   S.Kind = SK_ArrayLoopInit;
3550   S.Type = T;
3551   Steps.push_back(S);
3552 }
3553
3554 void InitializationSequence::AddParenthesizedArrayInitStep(QualType T) {
3555   Step S;
3556   S.Kind = SK_ParenthesizedArrayInit;
3557   S.Type = T;
3558   Steps.push_back(S);
3559 }
3560
3561 void InitializationSequence::AddPassByIndirectCopyRestoreStep(QualType type,
3562                                                               bool shouldCopy) {
3563   Step s;
3564   s.Kind = (shouldCopy ? SK_PassByIndirectCopyRestore
3565                        : SK_PassByIndirectRestore);
3566   s.Type = type;
3567   Steps.push_back(s);
3568 }
3569
3570 void InitializationSequence::AddProduceObjCObjectStep(QualType T) {
3571   Step S;
3572   S.Kind = SK_ProduceObjCObject;
3573   S.Type = T;
3574   Steps.push_back(S);
3575 }
3576
3577 void InitializationSequence::AddStdInitializerListConstructionStep(QualType T) {
3578   Step S;
3579   S.Kind = SK_StdInitializerList;
3580   S.Type = T;
3581   Steps.push_back(S);
3582 }
3583
3584 void InitializationSequence::AddOCLSamplerInitStep(QualType T) {
3585   Step S;
3586   S.Kind = SK_OCLSamplerInit;
3587   S.Type = T;
3588   Steps.push_back(S);
3589 }
3590
3591 void InitializationSequence::AddOCLZeroOpaqueTypeStep(QualType T) {
3592   Step S;
3593   S.Kind = SK_OCLZeroOpaqueType;
3594   S.Type = T;
3595   Steps.push_back(S);
3596 }
3597
3598 void InitializationSequence::RewrapReferenceInitList(QualType T,
3599                                                      InitListExpr *Syntactic) {
3600   assert(Syntactic->getNumInits() == 1 &&
3601          "Can only rewrap trivial init lists.");
3602   Step S;
3603   S.Kind = SK_UnwrapInitList;
3604   S.Type = Syntactic->getInit(0)->getType();
3605   Steps.insert(Steps.begin(), S);
3606
3607   S.Kind = SK_RewrapInitList;
3608   S.Type = T;
3609   S.WrappingSyntacticList = Syntactic;
3610   Steps.push_back(S);
3611 }
3612
3613 void InitializationSequence::SetOverloadFailure(FailureKind Failure,
3614                                                 OverloadingResult Result) {
3615   setSequenceKind(FailedSequence);
3616   this->Failure = Failure;
3617   this->FailedOverloadResult = Result;
3618 }
3619
3620 //===----------------------------------------------------------------------===//
3621 // Attempt initialization
3622 //===----------------------------------------------------------------------===//
3623
3624 /// Tries to add a zero initializer. Returns true if that worked.
3625 static bool
3626 maybeRecoverWithZeroInitialization(Sema &S, InitializationSequence &Sequence,
3627                                    const InitializedEntity &Entity) {
3628   if (Entity.getKind() != InitializedEntity::EK_Variable)
3629     return false;
3630
3631   VarDecl *VD = cast<VarDecl>(Entity.getDecl());
3632   if (VD->getInit() || VD->getEndLoc().isMacroID())
3633     return false;
3634
3635   QualType VariableTy = VD->getType().getCanonicalType();
3636   SourceLocation Loc = S.getLocForEndOfToken(VD->getEndLoc());
3637   std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
3638   if (!Init.empty()) {
3639     Sequence.AddZeroInitializationStep(Entity.getType());
3640     Sequence.SetZeroInitializationFixit(Init, Loc);
3641     return true;
3642   }
3643   return false;
3644 }
3645
3646 static void MaybeProduceObjCObject(Sema &S,
3647                                    InitializationSequence &Sequence,
3648                                    const InitializedEntity &Entity) {
3649   if (!S.getLangOpts().ObjCAutoRefCount) return;
3650
3651   /// When initializing a parameter, produce the value if it's marked
3652   /// __attribute__((ns_consumed)).
3653   if (Entity.isParameterKind()) {
3654     if (!Entity.isParameterConsumed())
3655       return;
3656
3657     assert(Entity.getType()->isObjCRetainableType() &&
3658            "consuming an object of unretainable type?");
3659     Sequence.AddProduceObjCObjectStep(Entity.getType());
3660
3661   /// When initializing a return value, if the return type is a
3662   /// retainable type, then returns need to immediately retain the
3663   /// object.  If an autorelease is required, it will be done at the
3664   /// last instant.
3665   } else if (Entity.getKind() == InitializedEntity::EK_Result ||
3666              Entity.getKind() == InitializedEntity::EK_StmtExprResult) {
3667     if (!Entity.getType()->isObjCRetainableType())
3668       return;
3669
3670     Sequence.AddProduceObjCObjectStep(Entity.getType());
3671   }
3672 }
3673
3674 static void TryListInitialization(Sema &S,
3675                                   const InitializedEntity &Entity,
3676                                   const InitializationKind &Kind,
3677                                   InitListExpr *InitList,
3678                                   InitializationSequence &Sequence,
3679                                   bool TreatUnavailableAsInvalid);
3680
3681 /// When initializing from init list via constructor, handle
3682 /// initialization of an object of type std::initializer_list<T>.
3683 ///
3684 /// \return true if we have handled initialization of an object of type
3685 /// std::initializer_list<T>, false otherwise.
3686 static bool TryInitializerListConstruction(Sema &S,
3687                                            InitListExpr *List,
3688                                            QualType DestType,
3689                                            InitializationSequence &Sequence,
3690                                            bool TreatUnavailableAsInvalid) {
3691   QualType E;
3692   if (!S.isStdInitializerList(DestType, &E))
3693     return false;
3694
3695   if (!S.isCompleteType(List->getExprLoc(), E)) {
3696     Sequence.setIncompleteTypeFailure(E);
3697     return true;
3698   }
3699
3700   // Try initializing a temporary array from the init list.
3701   QualType ArrayType = S.Context.getConstantArrayType(
3702       E.withConst(), llvm::APInt(S.Context.getTypeSize(S.Context.getSizeType()),
3703                                  List->getNumInits()),
3704       clang::ArrayType::Normal, 0);
3705   InitializedEntity HiddenArray =
3706       InitializedEntity::InitializeTemporary(ArrayType);
3707   InitializationKind Kind = InitializationKind::CreateDirectList(
3708       List->getExprLoc(), List->getBeginLoc(), List->getEndLoc());
3709   TryListInitialization(S, HiddenArray, Kind, List, Sequence,
3710                         TreatUnavailableAsInvalid);
3711   if (Sequence)
3712     Sequence.AddStdInitializerListConstructionStep(DestType);
3713   return true;
3714 }
3715
3716 /// Determine if the constructor has the signature of a copy or move
3717 /// constructor for the type T of the class in which it was found. That is,
3718 /// determine if its first parameter is of type T or reference to (possibly
3719 /// cv-qualified) T.
3720 static bool hasCopyOrMoveCtorParam(ASTContext &Ctx,
3721                                    const ConstructorInfo &Info) {
3722   if (Info.Constructor->getNumParams() == 0)
3723     return false;
3724
3725   QualType ParmT =
3726       Info.Constructor->getParamDecl(0)->getType().getNonReferenceType();
3727   QualType ClassT =
3728       Ctx.getRecordType(cast<CXXRecordDecl>(Info.FoundDecl->getDeclContext()));
3729
3730   return Ctx.hasSameUnqualifiedType(ParmT, ClassT);
3731 }
3732
3733 static OverloadingResult
3734 ResolveConstructorOverload(Sema &S, SourceLocation DeclLoc,
3735                            MultiExprArg Args,
3736                            OverloadCandidateSet &CandidateSet,
3737                            QualType DestType,
3738                            DeclContext::lookup_result Ctors,
3739                            OverloadCandidateSet::iterator &Best,
3740                            bool CopyInitializing, bool AllowExplicit,
3741                            bool OnlyListConstructors, bool IsListInit,
3742                            bool SecondStepOfCopyInit = false) {
3743   CandidateSet.clear(OverloadCandidateSet::CSK_InitByConstructor);
3744   CandidateSet.setDestAS(DestType.getQualifiers().getAddressSpace());
3745
3746   for (NamedDecl *D : Ctors) {
3747     auto Info = getConstructorInfo(D);
3748     if (!Info.Constructor || Info.Constructor->isInvalidDecl())
3749       continue;
3750
3751     if (!AllowExplicit && Info.Constructor->isExplicit())
3752       continue;
3753
3754     if (OnlyListConstructors && !S.isInitListConstructor(Info.Constructor))
3755       continue;
3756
3757     // C++11 [over.best.ics]p4:
3758     //   ... and the constructor or user-defined conversion function is a
3759     //   candidate by
3760     //   - 13.3.1.3, when the argument is the temporary in the second step
3761     //     of a class copy-initialization, or
3762     //   - 13.3.1.4, 13.3.1.5, or 13.3.1.6 (in all cases), [not handled here]
3763     //   - the second phase of 13.3.1.7 when the initializer list has exactly
3764     //     one element that is itself an initializer list, and the target is
3765     //     the first parameter of a constructor of class X, and the conversion
3766     //     is to X or reference to (possibly cv-qualified X),
3767     //   user-defined conversion sequences are not considered.
3768     bool SuppressUserConversions =
3769         SecondStepOfCopyInit ||
3770         (IsListInit && Args.size() == 1 && isa<InitListExpr>(Args[0]) &&
3771          hasCopyOrMoveCtorParam(S.Context, Info));
3772
3773     if (Info.ConstructorTmpl)
3774       S.AddTemplateOverloadCandidate(
3775           Info.ConstructorTmpl, Info.FoundDecl,
3776           /*ExplicitArgs*/ nullptr, Args, CandidateSet, SuppressUserConversions,
3777           /*PartialOverloading=*/false, AllowExplicit);
3778     else {
3779       // C++ [over.match.copy]p1:
3780       //   - When initializing a temporary to be bound to the first parameter
3781       //     of a constructor [for type T] that takes a reference to possibly
3782       //     cv-qualified T as its first argument, called with a single
3783       //     argument in the context of direct-initialization, explicit
3784       //     conversion functions are also considered.
3785       // FIXME: What if a constructor template instantiates to such a signature?
3786       bool AllowExplicitConv = AllowExplicit && !CopyInitializing &&
3787                                Args.size() == 1 &&
3788                                hasCopyOrMoveCtorParam(S.Context, Info);
3789       S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl, Args,
3790                              CandidateSet, SuppressUserConversions,
3791                              /*PartialOverloading=*/false, AllowExplicit,
3792                              AllowExplicitConv);
3793     }
3794   }
3795
3796   // FIXME: Work around a bug in C++17 guaranteed copy elision.
3797   //
3798   // When initializing an object of class type T by constructor
3799   // ([over.match.ctor]) or by list-initialization ([over.match.list])
3800   // from a single expression of class type U, conversion functions of
3801   // U that convert to the non-reference type cv T are candidates.
3802   // Explicit conversion functions are only candidates during
3803   // direct-initialization.
3804   //
3805   // Note: SecondStepOfCopyInit is only ever true in this case when
3806   // evaluating whether to produce a C++98 compatibility warning.
3807   if (S.getLangOpts().CPlusPlus17 && Args.size() == 1 &&
3808       !SecondStepOfCopyInit) {
3809     Expr *Initializer = Args[0];
3810     auto *SourceRD = Initializer->getType()->getAsCXXRecordDecl();
3811     if (SourceRD && S.isCompleteType(DeclLoc, Initializer->getType())) {
3812       const auto &Conversions = SourceRD->getVisibleConversionFunctions();
3813       for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
3814         NamedDecl *D = *I;
3815         CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
3816         D = D->getUnderlyingDecl();
3817
3818         FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
3819         CXXConversionDecl *Conv;
3820         if (ConvTemplate)
3821           Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
3822         else
3823           Conv = cast<CXXConversionDecl>(D);
3824
3825         if (AllowExplicit || !Conv->isExplicit()) {
3826           if (ConvTemplate)
3827             S.AddTemplateConversionCandidate(
3828                 ConvTemplate, I.getPair(), ActingDC, Initializer, DestType,
3829                 CandidateSet, AllowExplicit, AllowExplicit,
3830                 /*AllowResultConversion*/ false);
3831           else
3832             S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Initializer,
3833                                      DestType, CandidateSet, AllowExplicit,
3834                                      AllowExplicit,
3835                                      /*AllowResultConversion*/ false);
3836         }
3837       }
3838     }
3839   }
3840
3841   // Perform overload resolution and return the result.
3842   return CandidateSet.BestViableFunction(S, DeclLoc, Best);
3843 }
3844
3845 /// Attempt initialization by constructor (C++ [dcl.init]), which
3846 /// enumerates the constructors of the initialized entity and performs overload
3847 /// resolution to select the best.
3848 /// \param DestType       The destination class type.
3849 /// \param DestArrayType  The destination type, which is either DestType or
3850 ///                       a (possibly multidimensional) array of DestType.
3851 /// \param IsListInit     Is this list-initialization?
3852 /// \param IsInitListCopy Is this non-list-initialization resulting from a
3853 ///                       list-initialization from {x} where x is the same
3854 ///                       type as the entity?
3855 static void TryConstructorInitialization(Sema &S,
3856                                          const InitializedEntity &Entity,
3857                                          const InitializationKind &Kind,
3858                                          MultiExprArg Args, QualType DestType,
3859                                          QualType DestArrayType,
3860                                          InitializationSequence &Sequence,
3861                                          bool IsListInit = false,
3862                                          bool IsInitListCopy = false) {
3863   assert(((!IsListInit && !IsInitListCopy) ||
3864           (Args.size() == 1 && isa<InitListExpr>(Args[0]))) &&
3865          "IsListInit/IsInitListCopy must come with a single initializer list "
3866          "argument.");
3867   InitListExpr *ILE =
3868       (IsListInit || IsInitListCopy) ? cast<InitListExpr>(Args[0]) : nullptr;
3869   MultiExprArg UnwrappedArgs =
3870       ILE ? MultiExprArg(ILE->getInits(), ILE->getNumInits()) : Args;
3871
3872   // The type we're constructing needs to be complete.
3873   if (!S.isCompleteType(Kind.getLocation(), DestType)) {
3874     Sequence.setIncompleteTypeFailure(DestType);
3875     return;
3876   }
3877
3878   // C++17 [dcl.init]p17:
3879   //     - If the initializer expression is a prvalue and the cv-unqualified
3880   //       version of the source type is the same class as the class of the
3881   //       destination, the initializer expression is used to initialize the
3882   //       destination object.
3883   // Per DR (no number yet), this does not apply when initializing a base
3884   // class or delegating to another constructor from a mem-initializer.
3885   // ObjC++: Lambda captured by the block in the lambda to block conversion
3886   // should avoid copy elision.
3887   if (S.getLangOpts().CPlusPlus17 &&
3888       Entity.getKind() != InitializedEntity::EK_Base &&
3889       Entity.getKind() != InitializedEntity::EK_Delegating &&
3890       Entity.getKind() !=
3891           InitializedEntity::EK_LambdaToBlockConversionBlockElement &&
3892       UnwrappedArgs.size() == 1 && UnwrappedArgs[0]->isRValue() &&
3893       S.Context.hasSameUnqualifiedType(UnwrappedArgs[0]->getType(), DestType)) {
3894     // Convert qualifications if necessary.
3895     Sequence.AddQualificationConversionStep(DestType, VK_RValue);
3896     if (ILE)
3897       Sequence.RewrapReferenceInitList(DestType, ILE);
3898     return;
3899   }
3900
3901   const RecordType *DestRecordType = DestType->getAs<RecordType>();
3902   assert(DestRecordType && "Constructor initialization requires record type");
3903   CXXRecordDecl *DestRecordDecl
3904     = cast<CXXRecordDecl>(DestRecordType->getDecl());
3905
3906   // Build the candidate set directly in the initialization sequence
3907   // structure, so that it will persist if we fail.
3908   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
3909
3910   // Determine whether we are allowed to call explicit constructors or
3911   // explicit conversion operators.
3912   bool AllowExplicit = Kind.AllowExplicit() || IsListInit;
3913   bool CopyInitialization = Kind.getKind() == InitializationKind::IK_Copy;
3914
3915   //   - Otherwise, if T is a class type, constructors are considered. The
3916   //     applicable constructors are enumerated, and the best one is chosen
3917   //     through overload resolution.
3918   DeclContext::lookup_result Ctors = S.LookupConstructors(DestRecordDecl);
3919
3920   OverloadingResult Result = OR_No_Viable_Function;
3921   OverloadCandidateSet::iterator Best;
3922   bool AsInitializerList = false;
3923
3924   // C++11 [over.match.list]p1, per DR1467:
3925   //   When objects of non-aggregate type T are list-initialized, such that
3926   //   8.5.4 [dcl.init.list] specifies that overload resolution is performed
3927   //   according to the rules in this section, overload resolution selects
3928   //   the constructor in two phases:
3929   //
3930   //   - Initially, the candidate functions are the initializer-list
3931   //     constructors of the class T and the argument list consists of the
3932   //     initializer list as a single argument.
3933   if (IsListInit) {
3934     AsInitializerList = true;
3935
3936     // If the initializer list has no elements and T has a default constructor,
3937     // the first phase is omitted.
3938     if (!(UnwrappedArgs.empty() && DestRecordDecl->hasDefaultConstructor()))
3939       Result = ResolveConstructorOverload(S, Kind.getLocation(), Args,
3940                                           CandidateSet, DestType, Ctors, Best,
3941                                           CopyInitialization, AllowExplicit,
3942                                           /*OnlyListConstructors=*/true,
3943                                           IsListInit);
3944   }
3945
3946   // C++11 [over.match.list]p1:
3947   //   - If no viable initializer-list constructor is found, overload resolution
3948   //     is performed again, where the candidate functions are all the
3949   //     constructors of the class T and the argument list consists of the
3950   //     elements of the initializer list.
3951   if (Result == OR_No_Viable_Function) {
3952     AsInitializerList = false;
3953     Result = ResolveConstructorOverload(S, Kind.getLocation(), UnwrappedArgs,
3954                                         CandidateSet, DestType, Ctors, Best,
3955                                         CopyInitialization, AllowExplicit,
3956                                         /*OnlyListConstructors=*/false,
3957                                         IsListInit);
3958   }
3959   if (Result) {
3960     Sequence.SetOverloadFailure(IsListInit ?
3961                       InitializationSequence::FK_ListConstructorOverloadFailed :
3962                       InitializationSequence::FK_ConstructorOverloadFailed,
3963                                 Result);
3964     return;
3965   }
3966
3967   bool HadMultipleCandidates = (CandidateSet.size() > 1);
3968
3969   // In C++17, ResolveConstructorOverload can select a conversion function
3970   // instead of a constructor.
3971   if (auto *CD = dyn_cast<CXXConversionDecl>(Best->Function)) {
3972     // Add the user-defined conversion step that calls the conversion function.
3973     QualType ConvType = CD->getConversionType();
3974     assert(S.Context.hasSameUnqualifiedType(ConvType, DestType) &&
3975            "should not have selected this conversion function");
3976     Sequence.AddUserConversionStep(CD, Best->FoundDecl, ConvType,
3977                                    HadMultipleCandidates);
3978     if (!S.Context.hasSameType(ConvType, DestType))
3979       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
3980     if (IsListInit)
3981       Sequence.RewrapReferenceInitList(Entity.getType(), ILE);
3982     return;
3983   }
3984
3985   // C++11 [dcl.init]p6:
3986   //   If a program calls for the default initialization of an object
3987   //   of a const-qualified type T, T shall be a class type with a
3988   //   user-provided default constructor.
3989   // C++ core issue 253 proposal:
3990   //   If the implicit default constructor initializes all subobjects, no
3991   //   initializer should be required.
3992   // The 253 proposal is for example needed to process libstdc++ headers in 5.x.
3993   CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
3994   if (Kind.getKind() == InitializationKind::IK_Default &&
3995       Entity.getType().isConstQualified()) {
3996     if (!CtorDecl->getParent()->allowConstDefaultInit()) {
3997       if (!maybeRecoverWithZeroInitialization(S, Sequence, Entity))
3998         Sequence.SetFailed(InitializationSequence::FK_DefaultInitOfConst);
3999       return;
4000     }
4001   }
4002
4003   // C++11 [over.match.list]p1:
4004   //   In copy-list-initialization, if an explicit constructor is chosen, the
4005   //   initializer is ill-formed.
4006   if (IsListInit && !Kind.AllowExplicit() && CtorDecl->isExplicit()) {
4007     Sequence.SetFailed(InitializationSequence::FK_ExplicitConstructor);
4008     return;
4009   }
4010
4011   // Add the constructor initialization step. Any cv-qualification conversion is
4012   // subsumed by the initialization.
4013   Sequence.AddConstructorInitializationStep(
4014       Best->FoundDecl, CtorDecl, DestArrayType, HadMultipleCandidates,
4015       IsListInit | IsInitListCopy, AsInitializerList);
4016 }
4017
4018 static bool
4019 ResolveOverloadedFunctionForReferenceBinding(Sema &S,
4020                                              Expr *Initializer,
4021                                              QualType &SourceType,
4022                                              QualType &UnqualifiedSourceType,
4023                                              QualType UnqualifiedTargetType,
4024                                              InitializationSequence &Sequence) {
4025   if (S.Context.getCanonicalType(UnqualifiedSourceType) ==
4026         S.Context.OverloadTy) {
4027     DeclAccessPair Found;
4028     bool HadMultipleCandidates = false;
4029     if (FunctionDecl *Fn
4030         = S.ResolveAddressOfOverloadedFunction(Initializer,
4031                                                UnqualifiedTargetType,
4032                                                false, Found,
4033                                                &HadMultipleCandidates)) {
4034       Sequence.AddAddressOverloadResolutionStep(Fn, Found,
4035                                                 HadMultipleCandidates);
4036       SourceType = Fn->getType();
4037       UnqualifiedSourceType = SourceType.getUnqualifiedType();
4038     } else if (!UnqualifiedTargetType->isRecordType()) {
4039       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
4040       return true;
4041     }
4042   }
4043   return false;
4044 }
4045
4046 static void TryReferenceInitializationCore(Sema &S,
4047                                            const InitializedEntity &Entity,
4048                                            const InitializationKind &Kind,
4049                                            Expr *Initializer,
4050                                            QualType cv1T1, QualType T1,
4051                                            Qualifiers T1Quals,
4052                                            QualType cv2T2, QualType T2,
4053                                            Qualifiers T2Quals,
4054                                            InitializationSequence &Sequence);
4055
4056 static void TryValueInitialization(Sema &S,
4057                                    const InitializedEntity &Entity,
4058                                    const InitializationKind &Kind,
4059                                    InitializationSequence &Sequence,
4060                                    InitListExpr *InitList = nullptr);
4061
4062 /// Attempt list initialization of a reference.
4063 static void TryReferenceListInitialization(Sema &S,
4064                                            const InitializedEntity &Entity,
4065                                            const InitializationKind &Kind,
4066                                            InitListExpr *InitList,
4067                                            InitializationSequence &Sequence,
4068                                            bool TreatUnavailableAsInvalid) {
4069   // First, catch C++03 where this isn't possible.
4070   if (!S.getLangOpts().CPlusPlus11) {
4071     Sequence.SetFailed(InitializationSequence::FK_ReferenceBindingToInitList);
4072     return;
4073   }
4074   // Can't reference initialize a compound literal.
4075   if (Entity.getKind() == InitializedEntity::EK_CompoundLiteralInit) {
4076     Sequence.SetFailed(InitializationSequence::FK_ReferenceBindingToInitList);
4077     return;
4078   }
4079
4080   QualType DestType = Entity.getType();
4081   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
4082   Qualifiers T1Quals;
4083   QualType T1 = S.Context.getUnqualifiedArrayType(cv1T1, T1Quals);
4084
4085   // Reference initialization via an initializer list works thus:
4086   // If the initializer list consists of a single element that is
4087   // reference-related to the referenced type, bind directly to that element
4088   // (possibly creating temporaries).
4089   // Otherwise, initialize a temporary with the initializer list and
4090   // bind to that.
4091   if (InitList->getNumInits() == 1) {
4092     Expr *Initializer = InitList->getInit(0);
4093     QualType cv2T2 = Initializer->getType();
4094     Qualifiers T2Quals;
4095     QualType T2 = S.Context.getUnqualifiedArrayType(cv2T2, T2Quals);
4096
4097     // If this fails, creating a temporary wouldn't work either.
4098     if (ResolveOverloadedFunctionForReferenceBinding(S, Initializer, cv2T2, T2,
4099                                                      T1, Sequence))
4100       return;
4101
4102     SourceLocation DeclLoc = Initializer->getBeginLoc();
4103     bool dummy1, dummy2, dummy3;
4104     Sema::ReferenceCompareResult RefRelationship
4105       = S.CompareReferenceRelationship(DeclLoc, cv1T1, cv2T2, dummy1,
4106                                        dummy2, dummy3);
4107     if (RefRelationship >= Sema::Ref_Related) {
4108       // Try to bind the reference here.
4109       TryReferenceInitializationCore(S, Entity, Kind, Initializer, cv1T1, T1,
4110                                      T1Quals, cv2T2, T2, T2Quals, Sequence);
4111       if (Sequence)
4112         Sequence.RewrapReferenceInitList(cv1T1, InitList);
4113       return;
4114     }
4115
4116     // Update the initializer if we've resolved an overloaded function.
4117     if (Sequence.step_begin() != Sequence.step_end())
4118       Sequence.RewrapReferenceInitList(cv1T1, InitList);
4119   }
4120
4121   // Not reference-related. Create a temporary and bind to that.
4122   InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(cv1T1);
4123
4124   TryListInitialization(S, TempEntity, Kind, InitList, Sequence,
4125                         TreatUnavailableAsInvalid);
4126   if (Sequence) {
4127     if (DestType->isRValueReferenceType() ||
4128         (T1Quals.hasConst() && !T1Quals.hasVolatile()))
4129       Sequence.AddReferenceBindingStep(cv1T1, /*BindingTemporary=*/true);
4130     else
4131       Sequence.SetFailed(
4132           InitializationSequence::FK_NonConstLValueReferenceBindingToTemporary);
4133   }
4134 }
4135
4136 /// Attempt list initialization (C++0x [dcl.init.list])
4137 static void TryListInitialization(Sema &S,
4138                                   const InitializedEntity &Entity,
4139                                   const InitializationKind &Kind,
4140                                   InitListExpr *InitList,
4141                                   InitializationSequence &Sequence,
4142                                   bool TreatUnavailableAsInvalid) {
4143   QualType DestType = Entity.getType();
4144
4145   // C++ doesn't allow scalar initialization with more than one argument.
4146   // But C99 complex numbers are scalars and it makes sense there.
4147   if (S.getLangOpts().CPlusPlus && DestType->isScalarType() &&
4148       !DestType->isAnyComplexType() && InitList->getNumInits() > 1) {
4149     Sequence.SetFailed(InitializationSequence::FK_TooManyInitsForScalar);
4150     return;
4151   }
4152   if (DestType->isReferenceType()) {
4153     TryReferenceListInitialization(S, Entity, Kind, InitList, Sequence,
4154                                    TreatUnavailableAsInvalid);
4155     return;
4156   }
4157
4158   if (DestType->isRecordType() &&
4159       !S.isCompleteType(InitList->getBeginLoc(), DestType)) {
4160     Sequence.setIncompleteTypeFailure(DestType);
4161     return;
4162   }
4163
4164   // C++11 [dcl.init.list]p3, per DR1467:
4165   // - If T is a class type and the initializer list has a single element of
4166   //   type cv U, where U is T or a class derived from T, the object is
4167   //   initialized from that element (by copy-initialization for
4168   //   copy-list-initialization, or by direct-initialization for
4169   //   direct-list-initialization).
4170   // - Otherwise, if T is a character array and the initializer list has a
4171   //   single element that is an appropriately-typed string literal
4172   //   (8.5.2 [dcl.init.string]), initialization is performed as described
4173   //   in that section.
4174   // - Otherwise, if T is an aggregate, [...] (continue below).
4175   if (S.getLangOpts().CPlusPlus11 && InitList->getNumInits() == 1) {
4176     if (DestType->isRecordType()) {
4177       QualType InitType = InitList->getInit(0)->getType();
4178       if (S.Context.hasSameUnqualifiedType(InitType, DestType) ||
4179           S.IsDerivedFrom(InitList->getBeginLoc(), InitType, DestType)) {
4180         Expr *InitListAsExpr = InitList;
4181         TryConstructorInitialization(S, Entity, Kind, InitListAsExpr, DestType,
4182                                      DestType, Sequence,
4183                                      /*InitListSyntax*/false,
4184                                      /*IsInitListCopy*/true);
4185         return;
4186       }
4187     }
4188     if (const ArrayType *DestAT = S.Context.getAsArrayType(DestType)) {
4189       Expr *SubInit[1] = {InitList->getInit(0)};
4190       if (!isa<VariableArrayType>(DestAT) &&
4191           IsStringInit(SubInit[0], DestAT, S.Context) == SIF_None) {
4192         InitializationKind SubKind =
4193             Kind.getKind() == InitializationKind::IK_DirectList
4194                 ? InitializationKind::CreateDirect(Kind.getLocation(),
4195                                                    InitList->getLBraceLoc(),
4196                                                    InitList->getRBraceLoc())
4197                 : Kind;
4198         Sequence.InitializeFrom(S, Entity, SubKind, SubInit,
4199                                 /*TopLevelOfInitList*/ true,
4200                                 TreatUnavailableAsInvalid);
4201
4202         // TryStringLiteralInitialization() (in InitializeFrom()) will fail if
4203         // the element is not an appropriately-typed string literal, in which
4204         // case we should proceed as in C++11 (below).
4205         if (Sequence) {
4206           Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4207           return;
4208         }
4209       }
4210     }
4211   }
4212
4213   // C++11 [dcl.init.list]p3:
4214   //   - If T is an aggregate, aggregate initialization is performed.
4215   if ((DestType->isRecordType() && !DestType->isAggregateType()) ||
4216       (S.getLangOpts().CPlusPlus11 &&
4217        S.isStdInitializerList(DestType, nullptr))) {
4218     if (S.getLangOpts().CPlusPlus11) {
4219       //   - Otherwise, if the initializer list has no elements and T is a
4220       //     class type with a default constructor, the object is
4221       //     value-initialized.
4222       if (InitList->getNumInits() == 0) {
4223         CXXRecordDecl *RD = DestType->getAsCXXRecordDecl();
4224         if (RD->hasDefaultConstructor()) {
4225           TryValueInitialization(S, Entity, Kind, Sequence, InitList);
4226           return;
4227         }
4228       }
4229
4230       //   - Otherwise, if T is a specialization of std::initializer_list<E>,
4231       //     an initializer_list object constructed [...]
4232       if (TryInitializerListConstruction(S, InitList, DestType, Sequence,
4233                                          TreatUnavailableAsInvalid))
4234         return;
4235
4236       //   - Otherwise, if T is a class type, constructors are considered.
4237       Expr *InitListAsExpr = InitList;
4238       TryConstructorInitialization(S, Entity, Kind, InitListAsExpr, DestType,
4239                                    DestType, Sequence, /*InitListSyntax*/true);
4240     } else
4241       Sequence.SetFailed(InitializationSequence::FK_InitListBadDestinationType);
4242     return;
4243   }
4244
4245   if (S.getLangOpts().CPlusPlus && !DestType->isAggregateType() &&
4246       InitList->getNumInits() == 1) {
4247     Expr *E = InitList->getInit(0);
4248
4249     //   - Otherwise, if T is an enumeration with a fixed underlying type,
4250     //     the initializer-list has a single element v, and the initialization
4251     //     is direct-list-initialization, the object is initialized with the
4252     //     value T(v); if a narrowing conversion is required to convert v to
4253     //     the underlying type of T, the program is ill-formed.
4254     auto *ET = DestType->getAs<EnumType>();
4255     if (S.getLangOpts().CPlusPlus17 &&
4256         Kind.getKind() == InitializationKind::IK_DirectList &&
4257         ET && ET->getDecl()->isFixed() &&
4258         !S.Context.hasSameUnqualifiedType(E->getType(), DestType) &&
4259         (E->getType()->isIntegralOrEnumerationType() ||
4260          E->getType()->isFloatingType())) {
4261       // There are two ways that T(v) can work when T is an enumeration type.
4262       // If there is either an implicit conversion sequence from v to T or
4263       // a conversion function that can convert from v to T, then we use that.
4264       // Otherwise, if v is of integral, enumeration, or floating-point type,
4265       // it is converted to the enumeration type via its underlying type.
4266       // There is no overlap possible between these two cases (except when the
4267       // source value is already of the destination type), and the first
4268       // case is handled by the general case for single-element lists below.
4269       ImplicitConversionSequence ICS;
4270       ICS.setStandard();
4271       ICS.Standard.setAsIdentityConversion();
4272       if (!E->isRValue())
4273         ICS.Standard.First = ICK_Lvalue_To_Rvalue;
4274       // If E is of a floating-point type, then the conversion is ill-formed
4275       // due to narrowing, but go through the motions in order to produce the
4276       // right diagnostic.
4277       ICS.Standard.Second = E->getType()->isFloatingType()
4278                                 ? ICK_Floating_Integral
4279                                 : ICK_Integral_Conversion;
4280       ICS.Standard.setFromType(E->getType());
4281       ICS.Standard.setToType(0, E->getType());
4282       ICS.Standard.setToType(1, DestType);
4283       ICS.Standard.setToType(2, DestType);
4284       Sequence.AddConversionSequenceStep(ICS, ICS.Standard.getToType(2),
4285                                          /*TopLevelOfInitList*/true);
4286       Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4287       return;
4288     }
4289
4290     //   - Otherwise, if the initializer list has a single element of type E
4291     //     [...references are handled above...], the object or reference is
4292     //     initialized from that element (by copy-initialization for
4293     //     copy-list-initialization, or by direct-initialization for
4294     //     direct-list-initialization); if a narrowing conversion is required
4295     //     to convert the element to T, the program is ill-formed.
4296     //
4297     // Per core-24034, this is direct-initialization if we were performing
4298     // direct-list-initialization and copy-initialization otherwise.
4299     // We can't use InitListChecker for this, because it always performs
4300     // copy-initialization. This only matters if we might use an 'explicit'
4301     // conversion operator, so we only need to handle the cases where the source
4302     // is of record type.
4303     if (InitList->getInit(0)->getType()->isRecordType()) {
4304       InitializationKind SubKind =
4305           Kind.getKind() == InitializationKind::IK_DirectList
4306               ? InitializationKind::CreateDirect(Kind.getLocation(),
4307                                                  InitList->getLBraceLoc(),
4308                                                  InitList->getRBraceLoc())
4309               : Kind;
4310       Expr *SubInit[1] = { InitList->getInit(0) };
4311       Sequence.InitializeFrom(S, Entity, SubKind, SubInit,
4312                               /*TopLevelOfInitList*/true,
4313                               TreatUnavailableAsInvalid);
4314       if (Sequence)
4315         Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4316       return;
4317     }
4318   }
4319
4320   InitListChecker CheckInitList(S, Entity, InitList,
4321           DestType, /*VerifyOnly=*/true, TreatUnavailableAsInvalid);
4322   if (CheckInitList.HadError()) {
4323     Sequence.SetFailed(InitializationSequence::FK_ListInitializationFailed);
4324     return;
4325   }
4326
4327   // Add the list initialization step with the built init list.
4328   Sequence.AddListInitializationStep(DestType);
4329 }
4330
4331 /// Try a reference initialization that involves calling a conversion
4332 /// function.
4333 static OverloadingResult TryRefInitWithConversionFunction(
4334     Sema &S, const InitializedEntity &Entity, const InitializationKind &Kind,
4335     Expr *Initializer, bool AllowRValues, bool IsLValueRef,
4336     InitializationSequence &Sequence) {
4337   QualType DestType = Entity.getType();
4338   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
4339   QualType T1 = cv1T1.getUnqualifiedType();
4340   QualType cv2T2 = Initializer->getType();
4341   QualType T2 = cv2T2.getUnqualifiedType();
4342
4343   bool DerivedToBase;
4344   bool ObjCConversion;
4345   bool ObjCLifetimeConversion;
4346   assert(!S.CompareReferenceRelationship(Initializer->getBeginLoc(), T1, T2,
4347                                          DerivedToBase, ObjCConversion,
4348                                          ObjCLifetimeConversion) &&
4349          "Must have incompatible references when binding via conversion");
4350   (void)DerivedToBase;
4351   (void)ObjCConversion;
4352   (void)ObjCLifetimeConversion;
4353
4354   // Build the candidate set directly in the initialization sequence
4355   // structure, so that it will persist if we fail.
4356   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
4357   CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
4358
4359   // Determine whether we are allowed to call explicit conversion operators.
4360   // Note that none of [over.match.copy], [over.match.conv], nor
4361   // [over.match.ref] permit an explicit constructor to be chosen when
4362   // initializing a reference, not even for direct-initialization.
4363   bool AllowExplicitCtors = false;
4364   bool AllowExplicitConvs = Kind.allowExplicitConversionFunctionsInRefBinding();
4365
4366   const RecordType *T1RecordType = nullptr;
4367   if (AllowRValues && (T1RecordType = T1->getAs<RecordType>()) &&
4368       S.isCompleteType(Kind.getLocation(), T1)) {
4369     // The type we're converting to is a class type. Enumerate its constructors
4370     // to see if there is a suitable conversion.
4371     CXXRecordDecl *T1RecordDecl = cast<CXXRecordDecl>(T1RecordType->getDecl());
4372
4373     for (NamedDecl *D : S.LookupConstructors(T1RecordDecl)) {
4374       auto Info = getConstructorInfo(D);
4375       if (!Info.Constructor)
4376         continue;
4377
4378       if (!Info.Constructor->isInvalidDecl() &&
4379           Info.Constructor->isConvertingConstructor(AllowExplicitCtors)) {
4380         if (Info.ConstructorTmpl)
4381           S.AddTemplateOverloadCandidate(
4382               Info.ConstructorTmpl, Info.FoundDecl,
4383               /*ExplicitArgs*/ nullptr, Initializer, CandidateSet,
4384               /*SuppressUserConversions=*/true,
4385               /*PartialOverloading*/ false, AllowExplicitCtors);
4386         else
4387           S.AddOverloadCandidate(
4388               Info.Constructor, Info.FoundDecl, Initializer, CandidateSet,
4389               /*SuppressUserConversions=*/true,
4390               /*PartialOverloading*/ false, AllowExplicitCtors);
4391       }
4392     }
4393   }
4394   if (T1RecordType && T1RecordType->getDecl()->isInvalidDecl())
4395     return OR_No_Viable_Function;
4396
4397   const RecordType *T2RecordType = nullptr;
4398   if ((T2RecordType = T2->getAs<RecordType>()) &&
4399       S.isCompleteType(Kind.getLocation(), T2)) {
4400     // The type we're converting from is a class type, enumerate its conversion
4401     // functions.
4402     CXXRecordDecl *T2RecordDecl = cast<CXXRecordDecl>(T2RecordType->getDecl());
4403
4404     const auto &Conversions = T2RecordDecl->getVisibleConversionFunctions();
4405     for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
4406       NamedDecl *D = *I;
4407       CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
4408       if (isa<UsingShadowDecl>(D))
4409         D = cast<UsingShadowDecl>(D)->getTargetDecl();
4410
4411       FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
4412       CXXConversionDecl *Conv;
4413       if (ConvTemplate)
4414         Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
4415       else
4416         Conv = cast<CXXConversionDecl>(D);
4417
4418       // If the conversion function doesn't return a reference type,
4419       // it can't be considered for this conversion unless we're allowed to
4420       // consider rvalues.
4421       // FIXME: Do we need to make sure that we only consider conversion
4422       // candidates with reference-compatible results? That might be needed to
4423       // break recursion.
4424       if ((AllowExplicitConvs || !Conv->isExplicit()) &&
4425           (AllowRValues ||
4426            Conv->getConversionType()->isLValueReferenceType())) {
4427         if (ConvTemplate)
4428           S.AddTemplateConversionCandidate(
4429               ConvTemplate, I.getPair(), ActingDC, Initializer, DestType,
4430               CandidateSet,
4431               /*AllowObjCConversionOnExplicit=*/false, AllowExplicitConvs);
4432         else
4433           S.AddConversionCandidate(
4434               Conv, I.getPair(), ActingDC, Initializer, DestType, CandidateSet,
4435               /*AllowObjCConversionOnExplicit=*/false, AllowExplicitConvs);
4436       }
4437     }
4438   }
4439   if (T2RecordType && T2RecordType->getDecl()->isInvalidDecl())
4440     return OR_No_Viable_Function;
4441
4442   SourceLocation DeclLoc = Initializer->getBeginLoc();
4443
4444   // Perform overload resolution. If it fails, return the failed result.
4445   OverloadCandidateSet::iterator Best;
4446   if (OverloadingResult Result
4447         = CandidateSet.BestViableFunction(S, DeclLoc, Best))
4448     return Result;
4449
4450   FunctionDecl *Function = Best->Function;
4451   // This is the overload that will be used for this initialization step if we
4452   // use this initialization. Mark it as referenced.
4453   Function->setReferenced();
4454
4455   // Compute the returned type and value kind of the conversion.
4456   QualType cv3T3;
4457   if (isa<CXXConversionDecl>(Function))
4458     cv3T3 = Function->getReturnType();
4459   else
4460     cv3T3 = T1;
4461
4462   ExprValueKind VK = VK_RValue;
4463   if (cv3T3->isLValueReferenceType())
4464     VK = VK_LValue;
4465   else if (const auto *RRef = cv3T3->getAs<RValueReferenceType>())
4466     VK = RRef->getPointeeType()->isFunctionType() ? VK_LValue : VK_XValue;
4467   cv3T3 = cv3T3.getNonLValueExprType(S.Context);
4468
4469   // Add the user-defined conversion step.
4470   bool HadMultipleCandidates = (CandidateSet.size() > 1);
4471   Sequence.AddUserConversionStep(Function, Best->FoundDecl, cv3T3,
4472                                  HadMultipleCandidates);
4473
4474   // Determine whether we'll need to perform derived-to-base adjustments or
4475   // other conversions.
4476   bool NewDerivedToBase = false;
4477   bool NewObjCConversion = false;
4478   bool NewObjCLifetimeConversion = false;
4479   Sema::ReferenceCompareResult NewRefRelationship
4480     = S.CompareReferenceRelationship(DeclLoc, T1, cv3T3,
4481                                      NewDerivedToBase, NewObjCConversion,
4482                                      NewObjCLifetimeConversion);
4483
4484   // Add the final conversion sequence, if necessary.
4485   if (NewRefRelationship == Sema::Ref_Incompatible) {
4486     assert(!isa<CXXConstructorDecl>(Function) &&
4487            "should not have conversion after constructor");
4488
4489     ImplicitConversionSequence ICS;
4490     ICS.setStandard();
4491     ICS.Standard = Best->FinalConversion;
4492     Sequence.AddConversionSequenceStep(ICS, ICS.Standard.getToType(2));
4493
4494     // Every implicit conversion results in a prvalue, except for a glvalue
4495     // derived-to-base conversion, which we handle below.
4496     cv3T3 = ICS.Standard.getToType(2);
4497     VK = VK_RValue;
4498   }
4499
4500   //   If the converted initializer is a prvalue, its type T4 is adjusted to
4501   //   type "cv1 T4" and the temporary materialization conversion is applied.
4502   //
4503   // We adjust the cv-qualifications to match the reference regardless of
4504   // whether we have a prvalue so that the AST records the change. In this
4505   // case, T4 is "cv3 T3".
4506   QualType cv1T4 = S.Context.getQualifiedType(cv3T3, cv1T1.getQualifiers());
4507   if (cv1T4.getQualifiers() != cv3T3.getQualifiers())
4508     Sequence.AddQualificationConversionStep(cv1T4, VK);
4509   Sequence.AddReferenceBindingStep(cv1T4, VK == VK_RValue);
4510   VK = IsLValueRef ? VK_LValue : VK_XValue;
4511
4512   if (NewDerivedToBase)
4513     Sequence.AddDerivedToBaseCastStep(cv1T1, VK);
4514   else if (NewObjCConversion)
4515     Sequence.AddObjCObjectConversionStep(cv1T1);
4516
4517   return OR_Success;
4518 }
4519
4520 static void CheckCXX98CompatAccessibleCopy(Sema &S,
4521                                            const InitializedEntity &Entity,
4522                                            Expr *CurInitExpr);
4523
4524 /// Attempt reference initialization (C++0x [dcl.init.ref])
4525 static void TryReferenceInitialization(Sema &S,
4526                                        const InitializedEntity &Entity,
4527                                        const InitializationKind &Kind,
4528                                        Expr *Initializer,
4529                                        InitializationSequence &Sequence) {
4530   QualType DestType = Entity.getType();
4531   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
4532   Qualifiers T1Quals;
4533   QualType T1 = S.Context.getUnqualifiedArrayType(cv1T1, T1Quals);
4534   QualType cv2T2 = Initializer->getType();
4535   Qualifiers T2Quals;
4536   QualType T2 = S.Context.getUnqualifiedArrayType(cv2T2, T2Quals);
4537
4538   // If the initializer is the address of an overloaded function, try
4539   // to resolve the overloaded function. If all goes well, T2 is the
4540   // type of the resulting function.
4541   if (ResolveOverloadedFunctionForReferenceBinding(S, Initializer, cv2T2, T2,
4542                                                    T1, Sequence))
4543     return;
4544
4545   // Delegate everything else to a subfunction.
4546   TryReferenceInitializationCore(S, Entity, Kind, Initializer, cv1T1, T1,
4547                                  T1Quals, cv2T2, T2, T2Quals, Sequence);
4548 }
4549
4550 /// Determine whether an expression is a non-referenceable glvalue (one to
4551 /// which a reference can never bind). Attempting to bind a reference to
4552 /// such a glvalue will always create a temporary.
4553 static bool isNonReferenceableGLValue(Expr *E) {
4554   return E->refersToBitField() || E->refersToVectorElement();
4555 }
4556
4557 /// Reference initialization without resolving overloaded functions.
4558 static void TryReferenceInitializationCore(Sema &S,
4559                                            const InitializedEntity &Entity,
4560                                            const InitializationKind &Kind,
4561                                            Expr *Initializer,
4562                                            QualType cv1T1, QualType T1,
4563                                            Qualifiers T1Quals,
4564                                            QualType cv2T2, QualType T2,
4565                                            Qualifiers T2Quals,
4566                                            InitializationSequence &Sequence) {
4567   QualType DestType = Entity.getType();
4568   SourceLocation DeclLoc = Initializer->getBeginLoc();
4569   // Compute some basic properties of the types and the initializer.
4570   bool isLValueRef = DestType->isLValueReferenceType();
4571   bool isRValueRef = !isLValueRef;
4572   bool DerivedToBase = false;
4573   bool ObjCConversion = false;
4574   bool ObjCLifetimeConversion = false;
4575   Expr::Classification InitCategory = Initializer->Classify(S.Context);
4576   Sema::ReferenceCompareResult RefRelationship
4577     = S.CompareReferenceRelationship(DeclLoc, cv1T1, cv2T2, DerivedToBase,
4578                                      ObjCConversion, ObjCLifetimeConversion);
4579
4580   // C++0x [dcl.init.ref]p5:
4581   //   A reference to type "cv1 T1" is initialized by an expression of type
4582   //   "cv2 T2" as follows:
4583   //
4584   //     - If the reference is an lvalue reference and the initializer
4585   //       expression
4586   // Note the analogous bullet points for rvalue refs to functions. Because
4587   // there are no function rvalues in C++, rvalue refs to functions are treated
4588   // like lvalue refs.
4589   OverloadingResult ConvOvlResult = OR_Success;
4590   bool T1Function = T1->isFunctionType();
4591   if (isLValueRef || T1Function) {
4592     if (InitCategory.isLValue() && !isNonReferenceableGLValue(Initializer) &&
4593         (RefRelationship == Sema::Ref_Compatible ||
4594          (Kind.isCStyleOrFunctionalCast() &&
4595           RefRelationship == Sema::Ref_Related))) {
4596       //   - is an lvalue (but is not a bit-field), and "cv1 T1" is
4597       //     reference-compatible with "cv2 T2," or
4598       if (T1Quals != T2Quals)
4599         // Convert to cv1 T2. This should only add qualifiers unless this is a
4600         // c-style cast. The removal of qualifiers in that case notionally
4601         // happens after the reference binding, but that doesn't matter.
4602         Sequence.AddQualificationConversionStep(
4603             S.Context.getQualifiedType(T2, T1Quals),
4604             Initializer->getValueKind());
4605       if (DerivedToBase)
4606         Sequence.AddDerivedToBaseCastStep(cv1T1, VK_LValue);
4607       else if (ObjCConversion)
4608         Sequence.AddObjCObjectConversionStep(cv1T1);
4609
4610       // We only create a temporary here when binding a reference to a
4611       // bit-field or vector element. Those cases are't supposed to be
4612       // handled by this bullet, but the outcome is the same either way.
4613       Sequence.AddReferenceBindingStep(cv1T1, false);
4614       return;
4615     }
4616
4617     //     - has a class type (i.e., T2 is a class type), where T1 is not
4618     //       reference-related to T2, and can be implicitly converted to an
4619     //       lvalue of type "cv3 T3," where "cv1 T1" is reference-compatible
4620     //       with "cv3 T3" (this conversion is selected by enumerating the
4621     //       applicable conversion functions (13.3.1.6) and choosing the best
4622     //       one through overload resolution (13.3)),
4623     // If we have an rvalue ref to function type here, the rhs must be
4624     // an rvalue. DR1287 removed the "implicitly" here.
4625     if (RefRelationship == Sema::Ref_Incompatible && T2->isRecordType() &&
4626         (isLValueRef || InitCategory.isRValue())) {
4627       ConvOvlResult = TryRefInitWithConversionFunction(
4628           S, Entity, Kind, Initializer, /*AllowRValues*/ isRValueRef,
4629           /*IsLValueRef*/ isLValueRef, Sequence);
4630       if (ConvOvlResult == OR_Success)
4631         return;
4632       if (ConvOvlResult != OR_No_Viable_Function)
4633         Sequence.SetOverloadFailure(
4634             InitializationSequence::FK_ReferenceInitOverloadFailed,
4635             ConvOvlResult);
4636     }
4637   }
4638
4639   //     - Otherwise, the reference shall be an lvalue reference to a
4640   //       non-volatile const type (i.e., cv1 shall be const), or the reference
4641   //       shall be an rvalue reference.
4642   //       For address spaces, we interpret this to mean that an addr space
4643   //       of a reference "cv1 T1" is a superset of addr space of "cv2 T2".
4644   if (isLValueRef && !(T1Quals.hasConst() && !T1Quals.hasVolatile() &&
4645                        T1Quals.isAddressSpaceSupersetOf(T2Quals))) {
4646     if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy)
4647       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
4648     else if (ConvOvlResult && !Sequence.getFailedCandidateSet().empty())
4649       Sequence.SetOverloadFailure(
4650                         InitializationSequence::FK_ReferenceInitOverloadFailed,
4651                                   ConvOvlResult);
4652     else if (!InitCategory.isLValue())
4653       Sequence.SetFailed(
4654           T1Quals.isAddressSpaceSupersetOf(T2Quals)
4655               ? InitializationSequence::
4656                     FK_NonConstLValueReferenceBindingToTemporary
4657               : InitializationSequence::FK_ReferenceInitDropsQualifiers);
4658     else {
4659       InitializationSequence::FailureKind FK;
4660       switch (RefRelationship) {
4661       case Sema::Ref_Compatible:
4662         if (Initializer->refersToBitField())
4663           FK = InitializationSequence::
4664               FK_NonConstLValueReferenceBindingToBitfield;
4665         else if (Initializer->refersToVectorElement())
4666           FK = InitializationSequence::
4667               FK_NonConstLValueReferenceBindingToVectorElement;
4668         else
4669           llvm_unreachable("unexpected kind of compatible initializer");
4670         break;
4671       case Sema::Ref_Related:
4672         FK = InitializationSequence::FK_ReferenceInitDropsQualifiers;
4673         break;
4674       case Sema::Ref_Incompatible:
4675         FK = InitializationSequence::
4676             FK_NonConstLValueReferenceBindingToUnrelated;
4677         break;
4678       }
4679       Sequence.SetFailed(FK);
4680     }
4681     return;
4682   }
4683
4684   //    - If the initializer expression
4685   //      - is an
4686   // [<=14] xvalue (but not a bit-field), class prvalue, array prvalue, or
4687   // [1z]   rvalue (but not a bit-field) or
4688   //        function lvalue and "cv1 T1" is reference-compatible with "cv2 T2"
4689   //
4690   // Note: functions are handled above and below rather than here...
4691   if (!T1Function &&
4692       (RefRelationship == Sema::Ref_Compatible ||
4693        (Kind.isCStyleOrFunctionalCast() &&
4694         RefRelationship == Sema::Ref_Related)) &&
4695       ((InitCategory.isXValue() && !isNonReferenceableGLValue(Initializer)) ||
4696        (InitCategory.isPRValue() &&
4697         (S.getLangOpts().CPlusPlus17 || T2->isRecordType() ||
4698          T2->isArrayType())))) {
4699     ExprValueKind ValueKind = InitCategory.isXValue() ? VK_XValue : VK_RValue;
4700     if (InitCategory.isPRValue() && T2->isRecordType()) {
4701       // The corresponding bullet in C++03 [dcl.init.ref]p5 gives the
4702       // compiler the freedom to perform a copy here or bind to the
4703       // object, while C++0x requires that we bind directly to the
4704       // object. Hence, we always bind to the object without making an
4705       // extra copy. However, in C++03 requires that we check for the
4706       // presence of a suitable copy constructor:
4707       //
4708       //   The constructor that would be used to make the copy shall
4709       //   be callable whether or not the copy is actually done.
4710       if (!S.getLangOpts().CPlusPlus11 && !S.getLangOpts().MicrosoftExt)
4711         Sequence.AddExtraneousCopyToTemporary(cv2T2);
4712       else if (S.getLangOpts().CPlusPlus11)
4713         CheckCXX98CompatAccessibleCopy(S, Entity, Initializer);
4714     }
4715
4716     // C++1z [dcl.init.ref]/5.2.1.2:
4717     //   If the converted initializer is a prvalue, its type T4 is adjusted
4718     //   to type "cv1 T4" and the temporary materialization conversion is
4719     //   applied.
4720     // Postpone address space conversions to after the temporary materialization
4721     // conversion to allow creating temporaries in the alloca address space.
4722     auto T1QualsIgnoreAS = T1Quals;
4723     auto T2QualsIgnoreAS = T2Quals;
4724     if (T1Quals.getAddressSpace() != T2Quals.getAddressSpace()) {
4725       T1QualsIgnoreAS.removeAddressSpace();
4726       T2QualsIgnoreAS.removeAddressSpace();
4727     }
4728     QualType cv1T4 = S.Context.getQualifiedType(cv2T2, T1QualsIgnoreAS);
4729     if (T1QualsIgnoreAS != T2QualsIgnoreAS)
4730       Sequence.AddQualificationConversionStep(cv1T4, ValueKind);
4731     Sequence.AddReferenceBindingStep(cv1T4, ValueKind == VK_RValue);
4732     ValueKind = isLValueRef ? VK_LValue : VK_XValue;
4733     // Add addr space conversion if required.
4734     if (T1Quals.getAddressSpace() != T2Quals.getAddressSpace()) {
4735       auto T4Quals = cv1T4.getQualifiers();
4736       T4Quals.addAddressSpace(T1Quals.getAddressSpace());
4737       QualType cv1T4WithAS = S.Context.getQualifiedType(T2, T4Quals);
4738       Sequence.AddQualificationConversionStep(cv1T4WithAS, ValueKind);
4739     }
4740
4741     //   In any case, the reference is bound to the resulting glvalue (or to
4742     //   an appropriate base class subobject).
4743     if (DerivedToBase)
4744       Sequence.AddDerivedToBaseCastStep(cv1T1, ValueKind);
4745     else if (ObjCConversion)
4746       Sequence.AddObjCObjectConversionStep(cv1T1);
4747     return;
4748   }
4749
4750   //       - has a class type (i.e., T2 is a class type), where T1 is not
4751   //         reference-related to T2, and can be implicitly converted to an
4752   //         xvalue, class prvalue, or function lvalue of type "cv3 T3",
4753   //         where "cv1 T1" is reference-compatible with "cv3 T3",
4754   //
4755   // DR1287 removes the "implicitly" here.
4756   if (T2->isRecordType()) {
4757     if (RefRelationship == Sema::Ref_Incompatible) {
4758       ConvOvlResult = TryRefInitWithConversionFunction(
4759           S, Entity, Kind, Initializer, /*AllowRValues*/ true,
4760           /*IsLValueRef*/ isLValueRef, Sequence);
4761       if (ConvOvlResult)
4762         Sequence.SetOverloadFailure(
4763             InitializationSequence::FK_ReferenceInitOverloadFailed,
4764             ConvOvlResult);
4765
4766       return;
4767     }
4768
4769     if (RefRelationship == Sema::Ref_Compatible &&
4770         isRValueRef && InitCategory.isLValue()) {
4771       Sequence.SetFailed(
4772         InitializationSequence::FK_RValueReferenceBindingToLValue);
4773       return;
4774     }
4775
4776     Sequence.SetFailed(InitializationSequence::FK_ReferenceInitDropsQualifiers);
4777     return;
4778   }
4779
4780   //      - Otherwise, a temporary of type "cv1 T1" is created and initialized
4781   //        from the initializer expression using the rules for a non-reference
4782   //        copy-initialization (8.5). The reference is then bound to the
4783   //        temporary. [...]
4784
4785   // Ignore address space of reference type at this point and perform address
4786   // space conversion after the reference binding step.
4787   QualType cv1T1IgnoreAS =
4788       T1Quals.hasAddressSpace()
4789           ? S.Context.getQualifiedType(T1, T1Quals.withoutAddressSpace())
4790           : cv1T1;
4791
4792   InitializedEntity TempEntity =
4793       InitializedEntity::InitializeTemporary(cv1T1IgnoreAS);
4794
4795   // FIXME: Why do we use an implicit conversion here rather than trying
4796   // copy-initialization?
4797   ImplicitConversionSequence ICS
4798     = S.TryImplicitConversion(Initializer, TempEntity.getType(),
4799                               /*SuppressUserConversions=*/false,
4800                               /*AllowExplicit=*/false,
4801                               /*FIXME:InOverloadResolution=*/false,
4802                               /*CStyle=*/Kind.isCStyleOrFunctionalCast(),
4803                               /*AllowObjCWritebackConversion=*/false);
4804
4805   if (ICS.isBad()) {
4806     // FIXME: Use the conversion function set stored in ICS to turn
4807     // this into an overloading ambiguity diagnostic. However, we need
4808     // to keep that set as an OverloadCandidateSet rather than as some
4809     // other kind of set.
4810     if (ConvOvlResult && !Sequence.getFailedCandidateSet().empty())
4811       Sequence.SetOverloadFailure(
4812                         InitializationSequence::FK_ReferenceInitOverloadFailed,
4813                                   ConvOvlResult);
4814     else if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy)
4815       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
4816     else
4817       Sequence.SetFailed(InitializationSequence::FK_ReferenceInitFailed);
4818     return;
4819   } else {
4820     Sequence.AddConversionSequenceStep(ICS, TempEntity.getType());
4821   }
4822
4823   //        [...] If T1 is reference-related to T2, cv1 must be the
4824   //        same cv-qualification as, or greater cv-qualification
4825   //        than, cv2; otherwise, the program is ill-formed.
4826   unsigned T1CVRQuals = T1Quals.getCVRQualifiers();
4827   unsigned T2CVRQuals = T2Quals.getCVRQualifiers();
4828   if ((RefRelationship == Sema::Ref_Related &&
4829        (T1CVRQuals | T2CVRQuals) != T1CVRQuals) ||
4830       !T1Quals.isAddressSpaceSupersetOf(T2Quals)) {
4831     Sequence.SetFailed(InitializationSequence::FK_ReferenceInitDropsQualifiers);
4832     return;
4833   }
4834
4835   //   [...] If T1 is reference-related to T2 and the reference is an rvalue
4836   //   reference, the initializer expression shall not be an lvalue.
4837   if (RefRelationship >= Sema::Ref_Related && !isLValueRef &&
4838       InitCategory.isLValue()) {
4839     Sequence.SetFailed(
4840                     InitializationSequence::FK_RValueReferenceBindingToLValue);
4841     return;
4842   }
4843
4844   Sequence.AddReferenceBindingStep(cv1T1IgnoreAS, /*BindingTemporary=*/true);
4845
4846   if (T1Quals.hasAddressSpace()) {
4847     if (!Qualifiers::isAddressSpaceSupersetOf(T1Quals.getAddressSpace(),
4848                                               LangAS::Default)) {
4849       Sequence.SetFailed(
4850           InitializationSequence::FK_ReferenceAddrspaceMismatchTemporary);
4851       return;
4852     }
4853     Sequence.AddQualificationConversionStep(cv1T1, isLValueRef ? VK_LValue
4854                                                                : VK_XValue);
4855   }
4856 }
4857
4858 /// Attempt character array initialization from a string literal
4859 /// (C++ [dcl.init.string], C99 6.7.8).
4860 static void TryStringLiteralInitialization(Sema &S,
4861                                            const InitializedEntity &Entity,
4862                                            const InitializationKind &Kind,
4863                                            Expr *Initializer,
4864                                        InitializationSequence &Sequence) {
4865   Sequence.AddStringInitStep(Entity.getType());
4866 }
4867
4868 /// Attempt value initialization (C++ [dcl.init]p7).
4869 static void TryValueInitialization(Sema &S,
4870                                    const InitializedEntity &Entity,
4871                                    const InitializationKind &Kind,
4872                                    InitializationSequence &Sequence,
4873                                    InitListExpr *InitList) {
4874   assert((!InitList || InitList->getNumInits() == 0) &&
4875          "Shouldn't use value-init for non-empty init lists");
4876
4877   // C++98 [dcl.init]p5, C++11 [dcl.init]p7:
4878   //
4879   //   To value-initialize an object of type T means:
4880   QualType T = Entity.getType();
4881
4882   //     -- if T is an array type, then each element is value-initialized;
4883   T = S.Context.getBaseElementType(T);
4884
4885   if (const RecordType *RT = T->getAs<RecordType>()) {
4886     if (CXXRecordDecl *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
4887       bool NeedZeroInitialization = true;
4888       // C++98:
4889       // -- if T is a class type (clause 9) with a user-declared constructor
4890       //    (12.1), then the default constructor for T is called (and the
4891       //    initialization is ill-formed if T has no accessible default
4892       //    constructor);
4893       // C++11:
4894       // -- if T is a class type (clause 9) with either no default constructor
4895       //    (12.1 [class.ctor]) or a default constructor that is user-provided
4896       //    or deleted, then the object is default-initialized;
4897       //
4898       // Note that the C++11 rule is the same as the C++98 rule if there are no
4899       // defaulted or deleted constructors, so we just use it unconditionally.
4900       CXXConstructorDecl *CD = S.LookupDefaultConstructor(ClassDecl);
4901       if (!CD || !CD->getCanonicalDecl()->isDefaulted() || CD->isDeleted())
4902         NeedZeroInitialization = false;
4903
4904       // -- if T is a (possibly cv-qualified) non-union class type without a
4905       //    user-provided or deleted default constructor, then the object is
4906       //    zero-initialized and, if T has a non-trivial default constructor,
4907       //    default-initialized;
4908       // The 'non-union' here was removed by DR1502. The 'non-trivial default
4909       // constructor' part was removed by DR1507.
4910       if (NeedZeroInitialization)
4911         Sequence.AddZeroInitializationStep(Entity.getType());
4912
4913       // C++03:
4914       // -- if T is a non-union class type without a user-declared constructor,
4915       //    then every non-static data member and base class component of T is
4916       //    value-initialized;
4917       // [...] A program that calls for [...] value-initialization of an
4918       // entity of reference type is ill-formed.
4919       //
4920       // C++11 doesn't need this handling, because value-initialization does not
4921       // occur recursively there, and the implicit default constructor is
4922       // defined as deleted in the problematic cases.
4923       if (!S.getLangOpts().CPlusPlus11 &&
4924           ClassDecl->hasUninitializedReferenceMember()) {
4925         Sequence.SetFailed(InitializationSequence::FK_TooManyInitsForReference);
4926         return;
4927       }
4928
4929       // If this is list-value-initialization, pass the empty init list on when
4930       // building the constructor call. This affects the semantics of a few
4931       // things (such as whether an explicit default constructor can be called).
4932       Expr *InitListAsExpr = InitList;
4933       MultiExprArg Args(&InitListAsExpr, InitList ? 1 : 0);
4934       bool InitListSyntax = InitList;
4935
4936       // FIXME: Instead of creating a CXXConstructExpr of array type here,
4937       // wrap a class-typed CXXConstructExpr in an ArrayInitLoopExpr.
4938       return TryConstructorInitialization(
4939           S, Entity, Kind, Args, T, Entity.getType(), Sequence, InitListSyntax);
4940     }
4941   }
4942
4943   Sequence.AddZeroInitializationStep(Entity.getType());
4944 }
4945
4946 /// Attempt default initialization (C++ [dcl.init]p6).
4947 static void TryDefaultInitialization(Sema &S,
4948                                      const InitializedEntity &Entity,
4949                                      const InitializationKind &Kind,
4950                                      InitializationSequence &Sequence) {
4951   assert(Kind.getKind() == InitializationKind::IK_Default);
4952
4953   // C++ [dcl.init]p6:
4954   //   To default-initialize an object of type T means:
4955   //     - if T is an array type, each element is default-initialized;
4956   QualType DestType = S.Context.getBaseElementType(Entity.getType());
4957
4958   //     - if T is a (possibly cv-qualified) class type (Clause 9), the default
4959   //       constructor for T is called (and the initialization is ill-formed if
4960   //       T has no accessible default constructor);
4961   if (DestType->isRecordType() && S.getLangOpts().CPlusPlus) {
4962     TryConstructorInitialization(S, Entity, Kind, None, DestType,
4963                                  Entity.getType(), Sequence);
4964     return;
4965   }
4966
4967   //     - otherwise, no initialization is performed.
4968
4969   //   If a program calls for the default initialization of an object of
4970   //   a const-qualified type T, T shall be a class type with a user-provided
4971   //   default constructor.
4972   if (DestType.isConstQualified() && S.getLangOpts().CPlusPlus) {
4973     if (!maybeRecoverWithZeroInitialization(S, Sequence, Entity))
4974       Sequence.SetFailed(InitializationSequence::FK_DefaultInitOfConst);
4975     return;
4976   }
4977
4978   // If the destination type has a lifetime property, zero-initialize it.
4979   if (DestType.getQualifiers().hasObjCLifetime()) {
4980     Sequence.AddZeroInitializationStep(Entity.getType());
4981     return;
4982   }
4983 }
4984
4985 /// Attempt a user-defined conversion between two types (C++ [dcl.init]),
4986 /// which enumerates all conversion functions and performs overload resolution
4987 /// to select the best.
4988 static void TryUserDefinedConversion(Sema &S,
4989                                      QualType DestType,
4990                                      const InitializationKind &Kind,
4991                                      Expr *Initializer,
4992                                      InitializationSequence &Sequence,
4993                                      bool TopLevelOfInitList) {
4994   assert(!DestType->isReferenceType() && "References are handled elsewhere");
4995   QualType SourceType = Initializer->getType();
4996   assert((DestType->isRecordType() || SourceType->isRecordType()) &&
4997          "Must have a class type to perform a user-defined conversion");
4998
4999   // Build the candidate set directly in the initialization sequence
5000   // structure, so that it will persist if we fail.
5001   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
5002   CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
5003   CandidateSet.setDestAS(DestType.getQualifiers().getAddressSpace());
5004
5005   // Determine whether we are allowed to call explicit constructors or
5006   // explicit conversion operators.
5007   bool AllowExplicit = Kind.AllowExplicit();
5008
5009   if (const RecordType *DestRecordType = DestType->getAs<RecordType>()) {
5010     // The type we're converting to is a class type. Enumerate its constructors
5011     // to see if there is a suitable conversion.
5012     CXXRecordDecl *DestRecordDecl
5013       = cast<CXXRecordDecl>(DestRecordType->getDecl());
5014
5015     // Try to complete the type we're converting to.
5016     if (S.isCompleteType(Kind.getLocation(), DestType)) {
5017       for (NamedDecl *D : S.LookupConstructors(DestRecordDecl)) {
5018         auto Info = getConstructorInfo(D);
5019         if (!Info.Constructor)
5020           continue;
5021
5022         if (!Info.Constructor->isInvalidDecl() &&
5023             Info.Constructor->isConvertingConstructor(AllowExplicit)) {
5024           if (Info.ConstructorTmpl)
5025             S.AddTemplateOverloadCandidate(
5026                 Info.ConstructorTmpl, Info.FoundDecl,
5027                 /*ExplicitArgs*/ nullptr, Initializer, CandidateSet,
5028                 /*SuppressUserConversions=*/true,
5029                 /*PartialOverloading*/ false, AllowExplicit);
5030           else
5031             S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl,
5032                                    Initializer, CandidateSet,
5033                                    /*SuppressUserConversions=*/true,
5034                                    /*PartialOverloading*/ false, AllowExplicit);
5035         }
5036       }
5037     }
5038   }
5039
5040   SourceLocation DeclLoc = Initializer->getBeginLoc();
5041
5042   if (const RecordType *SourceRecordType = SourceType->getAs<RecordType>()) {
5043     // The type we're converting from is a class type, enumerate its conversion
5044     // functions.
5045
5046     // We can only enumerate the conversion functions for a complete type; if
5047     // the type isn't complete, simply skip this step.
5048     if (S.isCompleteType(DeclLoc, SourceType)) {
5049       CXXRecordDecl *SourceRecordDecl
5050         = cast<CXXRecordDecl>(SourceRecordType->getDecl());
5051
5052       const auto &Conversions =
5053           SourceRecordDecl->getVisibleConversionFunctions();
5054       for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
5055         NamedDecl *D = *I;
5056         CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
5057         if (isa<UsingShadowDecl>(D))
5058           D = cast<UsingShadowDecl>(D)->getTargetDecl();
5059
5060         FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
5061         CXXConversionDecl *Conv;
5062         if (ConvTemplate)
5063           Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
5064         else
5065           Conv = cast<CXXConversionDecl>(D);
5066
5067         if (AllowExplicit || !Conv->isExplicit()) {
5068           if (ConvTemplate)
5069             S.AddTemplateConversionCandidate(
5070                 ConvTemplate, I.getPair(), ActingDC, Initializer, DestType,
5071                 CandidateSet, AllowExplicit, AllowExplicit);
5072           else
5073             S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Initializer,
5074                                      DestType, CandidateSet, AllowExplicit,
5075                                      AllowExplicit);
5076         }
5077       }
5078     }
5079   }
5080
5081   // Perform overload resolution. If it fails, return the failed result.
5082   OverloadCandidateSet::iterator Best;
5083   if (OverloadingResult Result
5084         = CandidateSet.BestViableFunction(S, DeclLoc, Best)) {
5085     Sequence.SetOverloadFailure(
5086                         InitializationSequence::FK_UserConversionOverloadFailed,
5087                                 Result);
5088     return;
5089   }
5090
5091   FunctionDecl *Function = Best->Function;
5092   Function->setReferenced();
5093   bool HadMultipleCandidates = (CandidateSet.size() > 1);
5094
5095   if (isa<CXXConstructorDecl>(Function)) {
5096     // Add the user-defined conversion step. Any cv-qualification conversion is
5097     // subsumed by the initialization. Per DR5, the created temporary is of the
5098     // cv-unqualified type of the destination.
5099     Sequence.AddUserConversionStep(Function, Best->FoundDecl,
5100                                    DestType.getUnqualifiedType(),
5101                                    HadMultipleCandidates);
5102
5103     // C++14 and before:
5104     //   - if the function is a constructor, the call initializes a temporary
5105     //     of the cv-unqualified version of the destination type. The [...]
5106     //     temporary [...] is then used to direct-initialize, according to the
5107     //     rules above, the object that is the destination of the
5108     //     copy-initialization.
5109     // Note that this just performs a simple object copy from the temporary.
5110     //
5111     // C++17:
5112     //   - if the function is a constructor, the call is a prvalue of the
5113     //     cv-unqualified version of the destination type whose return object
5114     //     is initialized by the constructor. The call is used to
5115     //     direct-initialize, according to the rules above, the object that
5116     //     is the destination of the copy-initialization.
5117     // Therefore we need to do nothing further.
5118     //
5119     // FIXME: Mark this copy as extraneous.
5120     if (!S.getLangOpts().CPlusPlus17)
5121       Sequence.AddFinalCopy(DestType);
5122     else if (DestType.hasQualifiers())
5123       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
5124     return;
5125   }
5126
5127   // Add the user-defined conversion step that calls the conversion function.
5128   QualType ConvType = Function->getCallResultType();
5129   Sequence.AddUserConversionStep(Function, Best->FoundDecl, ConvType,
5130                                  HadMultipleCandidates);
5131
5132   if (ConvType->getAs<RecordType>()) {
5133     //   The call is used to direct-initialize [...] the object that is the
5134     //   destination of the copy-initialization.
5135     //
5136     // In C++17, this does not call a constructor if we enter /17.6.1:
5137     //   - If the initializer expression is a prvalue and the cv-unqualified
5138     //     version of the source type is the same as the class of the
5139     //     destination [... do not make an extra copy]
5140     //
5141     // FIXME: Mark this copy as extraneous.
5142     if (!S.getLangOpts().CPlusPlus17 ||
5143         Function->getReturnType()->isReferenceType() ||
5144         !S.Context.hasSameUnqualifiedType(ConvType, DestType))
5145       Sequence.AddFinalCopy(DestType);
5146     else if (!S.Context.hasSameType(ConvType, DestType))
5147       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
5148     return;
5149   }
5150
5151   // If the conversion following the call to the conversion function
5152   // is interesting, add it as a separate step.
5153   if (Best->FinalConversion.First || Best->FinalConversion.Second ||
5154       Best->FinalConversion.Third) {
5155     ImplicitConversionSequence ICS;
5156     ICS.setStandard();
5157     ICS.Standard = Best->FinalConversion;
5158     Sequence.AddConversionSequenceStep(ICS, DestType, TopLevelOfInitList);
5159   }
5160 }
5161
5162 /// An egregious hack for compatibility with libstdc++-4.2: in <tr1/hashtable>,
5163 /// a function with a pointer return type contains a 'return false;' statement.
5164 /// In C++11, 'false' is not a null pointer, so this breaks the build of any
5165 /// code using that header.
5166 ///
5167 /// Work around this by treating 'return false;' as zero-initializing the result
5168 /// if it's used in a pointer-returning function in a system header.
5169 static bool isLibstdcxxPointerReturnFalseHack(Sema &S,
5170                                               const InitializedEntity &Entity,
5171                                               const Expr *Init) {
5172   return S.getLangOpts().CPlusPlus11 &&
5173          Entity.getKind() == InitializedEntity::EK_Result &&
5174          Entity.getType()->isPointerType() &&
5175          isa<CXXBoolLiteralExpr>(Init) &&
5176          !cast<CXXBoolLiteralExpr>(Init)->getValue() &&
5177          S.getSourceManager().isInSystemHeader(Init->getExprLoc());
5178 }
5179
5180 /// The non-zero enum values here are indexes into diagnostic alternatives.
5181 enum InvalidICRKind { IIK_okay, IIK_nonlocal, IIK_nonscalar };
5182
5183 /// Determines whether this expression is an acceptable ICR source.
5184 static InvalidICRKind isInvalidICRSource(ASTContext &C, Expr *e,
5185                                          bool isAddressOf, bool &isWeakAccess) {
5186   // Skip parens.
5187   e = e->IgnoreParens();
5188
5189   // Skip address-of nodes.
5190   if (UnaryOperator *op = dyn_cast<UnaryOperator>(e)) {
5191     if (op->getOpcode() == UO_AddrOf)
5192       return isInvalidICRSource(C, op->getSubExpr(), /*addressof*/ true,
5193                                 isWeakAccess);
5194
5195   // Skip certain casts.
5196   } else if (CastExpr *ce = dyn_cast<CastExpr>(e)) {
5197     switch (ce->getCastKind()) {
5198     case CK_Dependent:
5199     case CK_BitCast:
5200     case CK_LValueBitCast:
5201     case CK_NoOp:
5202       return isInvalidICRSource(C, ce->getSubExpr(), isAddressOf, isWeakAccess);
5203
5204     case CK_ArrayToPointerDecay:
5205       return IIK_nonscalar;
5206
5207     case CK_NullToPointer:
5208       return IIK_okay;
5209
5210     default:
5211       break;
5212     }
5213
5214   // If we have a declaration reference, it had better be a local variable.
5215   } else if (isa<DeclRefExpr>(e)) {
5216     // set isWeakAccess to true, to mean that there will be an implicit
5217     // load which requires a cleanup.
5218     if (e->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
5219       isWeakAccess = true;
5220
5221     if (!isAddressOf) return IIK_nonlocal;
5222
5223     VarDecl *var = dyn_cast<VarDecl>(cast<DeclRefExpr>(e)->getDecl());
5224     if (!var) return IIK_nonlocal;
5225
5226     return (var->hasLocalStorage() ? IIK_okay : IIK_nonlocal);
5227
5228   // If we have a conditional operator, check both sides.
5229   } else if (ConditionalOperator *cond = dyn_cast<ConditionalOperator>(e)) {
5230     if (InvalidICRKind iik = isInvalidICRSource(C, cond->getLHS(), isAddressOf,
5231                                                 isWeakAccess))
5232       return iik;
5233
5234     return isInvalidICRSource(C, cond->getRHS(), isAddressOf, isWeakAccess);
5235
5236   // These are never scalar.
5237   } else if (isa<ArraySubscriptExpr>(e)) {
5238     return IIK_nonscalar;
5239
5240   // Otherwise, it needs to be a null pointer constant.
5241   } else {
5242     return (e->isNullPointerConstant(C, Expr::NPC_ValueDependentIsNull)
5243             ? IIK_okay : IIK_nonlocal);
5244   }
5245
5246   return IIK_nonlocal;
5247 }
5248
5249 /// Check whether the given expression is a valid operand for an
5250 /// indirect copy/restore.
5251 static void checkIndirectCopyRestoreSource(Sema &S, Expr *src) {
5252   assert(src->isRValue());
5253   bool isWeakAccess = false;
5254   InvalidICRKind iik = isInvalidICRSource(S.Context, src, false, isWeakAccess);
5255   // If isWeakAccess to true, there will be an implicit
5256   // load which requires a cleanup.
5257   if (S.getLangOpts().ObjCAutoRefCount && isWeakAccess)
5258     S.Cleanup.setExprNeedsCleanups(true);
5259
5260   if (iik == IIK_okay) return;
5261
5262   S.Diag(src->getExprLoc(), diag::err_arc_nonlocal_writeback)
5263     << ((unsigned) iik - 1)  // shift index into diagnostic explanations
5264     << src->getSourceRange();
5265 }
5266
5267 /// Determine whether we have compatible array types for the
5268 /// purposes of GNU by-copy array initialization.
5269 static bool hasCompatibleArrayTypes(ASTContext &Context, const ArrayType *Dest,
5270                                     const ArrayType *Source) {
5271   // If the source and destination array types are equivalent, we're
5272   // done.
5273   if (Context.hasSameType(QualType(Dest, 0), QualType(Source, 0)))
5274     return true;
5275
5276   // Make sure that the element types are the same.
5277   if (!Context.hasSameType(Dest->getElementType(), Source->getElementType()))
5278     return false;
5279
5280   // The only mismatch we allow is when the destination is an
5281   // incomplete array type and the source is a constant array type.
5282   return Source->isConstantArrayType() && Dest->isIncompleteArrayType();
5283 }
5284
5285 static bool tryObjCWritebackConversion(Sema &S,
5286                                        InitializationSequence &Sequence,
5287                                        const InitializedEntity &Entity,
5288                                        Expr *Initializer) {
5289   bool ArrayDecay = false;
5290   QualType ArgType = Initializer->getType();
5291   QualType ArgPointee;
5292   if (const ArrayType *ArgArrayType = S.Context.getAsArrayType(ArgType)) {
5293     ArrayDecay = true;
5294     ArgPointee = ArgArrayType->getElementType();
5295     ArgType = S.Context.getPointerType(ArgPointee);
5296   }
5297
5298   // Handle write-back conversion.
5299   QualType ConvertedArgType;
5300   if (!S.isObjCWritebackConversion(ArgType, Entity.getType(),
5301                                    ConvertedArgType))
5302     return false;
5303
5304   // We should copy unless we're passing to an argument explicitly
5305   // marked 'out'.
5306   bool ShouldCopy = true;
5307   if (ParmVarDecl *param = cast_or_null<ParmVarDecl>(Entity.getDecl()))
5308     ShouldCopy = (param->getObjCDeclQualifier() != ParmVarDecl::OBJC_TQ_Out);
5309
5310   // Do we need an lvalue conversion?
5311   if (ArrayDecay || Initializer->isGLValue()) {
5312     ImplicitConversionSequence ICS;
5313     ICS.setStandard();
5314     ICS.Standard.setAsIdentityConversion();
5315
5316     QualType ResultType;
5317     if (ArrayDecay) {
5318       ICS.Standard.First = ICK_Array_To_Pointer;
5319       ResultType = S.Context.getPointerType(ArgPointee);
5320     } else {
5321       ICS.Standard.First = ICK_Lvalue_To_Rvalue;
5322       ResultType = Initializer->getType().getNonLValueExprType(S.Context);
5323     }
5324
5325     Sequence.AddConversionSequenceStep(ICS, ResultType);
5326   }
5327
5328   Sequence.AddPassByIndirectCopyRestoreStep(Entity.getType(), ShouldCopy);
5329   return true;
5330 }
5331
5332 static bool TryOCLSamplerInitialization(Sema &S,
5333                                         InitializationSequence &Sequence,
5334                                         QualType DestType,
5335                                         Expr *Initializer) {
5336   if (!S.getLangOpts().OpenCL || !DestType->isSamplerT() ||
5337       (!Initializer->isIntegerConstantExpr(S.Context) &&
5338       !Initializer->getType()->isSamplerT()))
5339     return false;
5340
5341   Sequence.AddOCLSamplerInitStep(DestType);
5342   return true;
5343 }
5344
5345 static bool IsZeroInitializer(Expr *Initializer, Sema &S) {
5346   return Initializer->isIntegerConstantExpr(S.getASTContext()) &&
5347     (Initializer->EvaluateKnownConstInt(S.getASTContext()) == 0);
5348 }
5349
5350 static bool TryOCLZeroOpaqueTypeInitialization(Sema &S,
5351                                                InitializationSequence &Sequence,
5352                                                QualType DestType,
5353                                                Expr *Initializer) {
5354   if (!S.getLangOpts().OpenCL)
5355     return false;
5356
5357   //
5358   // OpenCL 1.2 spec, s6.12.10
5359   //
5360   // The event argument can also be used to associate the
5361   // async_work_group_copy with a previous async copy allowing
5362   // an event to be shared by multiple async copies; otherwise
5363   // event should be zero.
5364   //
5365   if (DestType->isEventT() || DestType->isQueueT()) {
5366     if (!IsZeroInitializer(Initializer, S))
5367       return false;
5368
5369     Sequence.AddOCLZeroOpaqueTypeStep(DestType);
5370     return true;
5371   }
5372
5373   // We should allow zero initialization for all types defined in the
5374   // cl_intel_device_side_avc_motion_estimation extension, except
5375   // intel_sub_group_avc_mce_payload_t and intel_sub_group_avc_mce_result_t.
5376   if (S.getOpenCLOptions().isEnabled(
5377           "cl_intel_device_side_avc_motion_estimation") &&
5378       DestType->isOCLIntelSubgroupAVCType()) {
5379     if (DestType->isOCLIntelSubgroupAVCMcePayloadType() ||
5380         DestType->isOCLIntelSubgroupAVCMceResultType())
5381       return false;
5382     if (!IsZeroInitializer(Initializer, S))
5383       return false;
5384
5385     Sequence.AddOCLZeroOpaqueTypeStep(DestType);
5386     return true;
5387   }
5388
5389   return false;
5390 }
5391
5392 InitializationSequence::InitializationSequence(Sema &S,
5393                                                const InitializedEntity &Entity,
5394                                                const InitializationKind &Kind,
5395                                                MultiExprArg Args,
5396                                                bool TopLevelOfInitList,
5397                                                bool TreatUnavailableAsInvalid)
5398     : FailedCandidateSet(Kind.getLocation(), OverloadCandidateSet::CSK_Normal) {
5399   InitializeFrom(S, Entity, Kind, Args, TopLevelOfInitList,
5400                  TreatUnavailableAsInvalid);
5401 }
5402
5403 /// Tries to get a FunctionDecl out of `E`. If it succeeds and we can take the
5404 /// address of that function, this returns true. Otherwise, it returns false.
5405 static bool isExprAnUnaddressableFunction(Sema &S, const Expr *E) {
5406   auto *DRE = dyn_cast<DeclRefExpr>(E);
5407   if (!DRE || !isa<FunctionDecl>(DRE->getDecl()))
5408     return false;
5409
5410   return !S.checkAddressOfFunctionIsAvailable(
5411       cast<FunctionDecl>(DRE->getDecl()));
5412 }
5413
5414 /// Determine whether we can perform an elementwise array copy for this kind
5415 /// of entity.
5416 static bool canPerformArrayCopy(const InitializedEntity &Entity) {
5417   switch (Entity.getKind()) {
5418   case InitializedEntity::EK_LambdaCapture:
5419     // C++ [expr.prim.lambda]p24:
5420     //   For array members, the array elements are direct-initialized in
5421     //   increasing subscript order.
5422     return true;
5423
5424   case InitializedEntity::EK_Variable:
5425     // C++ [dcl.decomp]p1:
5426     //   [...] each element is copy-initialized or direct-initialized from the
5427     //   corresponding element of the assignment-expression [...]
5428     return isa<DecompositionDecl>(Entity.getDecl());
5429
5430   case InitializedEntity::EK_Member:
5431     // C++ [class.copy.ctor]p14:
5432     //   - if the member is an array, each element is direct-initialized with
5433     //     the corresponding subobject of x
5434     return Entity.isImplicitMemberInitializer();
5435
5436   case InitializedEntity::EK_ArrayElement:
5437     // All the above cases are intended to apply recursively, even though none
5438     // of them actually say that.
5439     if (auto *E = Entity.getParent())
5440       return canPerformArrayCopy(*E);
5441     break;
5442
5443   default:
5444     break;
5445   }
5446
5447   return false;
5448 }
5449
5450 void InitializationSequence::InitializeFrom(Sema &S,
5451                                             const InitializedEntity &Entity,
5452                                             const InitializationKind &Kind,
5453                                             MultiExprArg Args,
5454                                             bool TopLevelOfInitList,
5455                                             bool TreatUnavailableAsInvalid) {
5456   ASTContext &Context = S.Context;
5457
5458   // Eliminate non-overload placeholder types in the arguments.  We
5459   // need to do this before checking whether types are dependent
5460   // because lowering a pseudo-object expression might well give us
5461   // something of dependent type.
5462   for (unsigned I = 0, E = Args.size(); I != E; ++I)
5463     if (Args[I]->getType()->isNonOverloadPlaceholderType()) {
5464       // FIXME: should we be doing this here?
5465       ExprResult result = S.CheckPlaceholderExpr(Args[I]);
5466       if (result.isInvalid()) {
5467         SetFailed(FK_PlaceholderType);
5468         return;
5469       }
5470       Args[I] = result.get();
5471     }
5472
5473   // C++0x [dcl.init]p16:
5474   //   The semantics of initializers are as follows. The destination type is
5475   //   the type of the object or reference being initialized and the source
5476   //   type is the type of the initializer expression. The source type is not
5477   //   defined when the initializer is a braced-init-list or when it is a
5478   //   parenthesized list of expressions.
5479   QualType DestType = Entity.getType();
5480
5481   if (DestType->isDependentType() ||
5482       Expr::hasAnyTypeDependentArguments(Args)) {
5483     SequenceKind = DependentSequence;
5484     return;
5485   }
5486
5487   // Almost everything is a normal sequence.
5488   setSequenceKind(NormalSequence);
5489
5490   QualType SourceType;
5491   Expr *Initializer = nullptr;
5492   if (Args.size() == 1) {
5493     Initializer = Args[0];
5494     if (S.getLangOpts().ObjC) {
5495       if (S.CheckObjCBridgeRelatedConversions(Initializer->getBeginLoc(),
5496                                               DestType, Initializer->getType(),
5497                                               Initializer) ||
5498           S.ConversionToObjCStringLiteralCheck(DestType, Initializer))
5499         Args[0] = Initializer;
5500     }
5501     if (!isa<InitListExpr>(Initializer))
5502       SourceType = Initializer->getType();
5503   }
5504
5505   //     - If the initializer is a (non-parenthesized) braced-init-list, the
5506   //       object is list-initialized (8.5.4).
5507   if (Kind.getKind() != InitializationKind::IK_Direct) {
5508     if (InitListExpr *InitList = dyn_cast_or_null<InitListExpr>(Initializer)) {
5509       TryListInitialization(S, Entity, Kind, InitList, *this,
5510                             TreatUnavailableAsInvalid);
5511       return;
5512     }
5513   }
5514
5515   //     - If the destination type is a reference type, see 8.5.3.
5516   if (DestType->isReferenceType()) {
5517     // C++0x [dcl.init.ref]p1:
5518     //   A variable declared to be a T& or T&&, that is, "reference to type T"
5519     //   (8.3.2), shall be initialized by an object, or function, of type T or
5520     //   by an object that can be converted into a T.
5521     // (Therefore, multiple arguments are not permitted.)
5522     if (Args.size() != 1)
5523       SetFailed(FK_TooManyInitsForReference);
5524     // C++17 [dcl.init.ref]p5:
5525     //   A reference [...] is initialized by an expression [...] as follows:
5526     // If the initializer is not an expression, presumably we should reject,
5527     // but the standard fails to actually say so.
5528     else if (isa<InitListExpr>(Args[0]))
5529       SetFailed(FK_ParenthesizedListInitForReference);
5530     else
5531       TryReferenceInitialization(S, Entity, Kind, Args[0], *this);
5532     return;
5533   }
5534
5535   //     - If the initializer is (), the object is value-initialized.
5536   if (Kind.getKind() == InitializationKind::IK_Value ||
5537       (Kind.getKind() == InitializationKind::IK_Direct && Args.empty())) {
5538     TryValueInitialization(S, Entity, Kind, *this);
5539     return;
5540   }
5541
5542   // Handle default initialization.
5543   if (Kind.getKind() == InitializationKind::IK_Default) {
5544     TryDefaultInitialization(S, Entity, Kind, *this);
5545     return;
5546   }
5547
5548   //     - If the destination type is an array of characters, an array of
5549   //       char16_t, an array of char32_t, or an array of wchar_t, and the
5550   //       initializer is a string literal, see 8.5.2.
5551   //     - Otherwise, if the destination type is an array, the program is
5552   //       ill-formed.
5553   if (const ArrayType *DestAT = Context.getAsArrayType(DestType)) {
5554     if (Initializer && isa<VariableArrayType>(DestAT)) {
5555       SetFailed(FK_VariableLengthArrayHasInitializer);
5556       return;
5557     }
5558
5559     if (Initializer) {
5560       switch (IsStringInit(Initializer, DestAT, Context)) {
5561       case SIF_None:
5562         TryStringLiteralInitialization(S, Entity, Kind, Initializer, *this);
5563         return;
5564       case SIF_NarrowStringIntoWideChar:
5565         SetFailed(FK_NarrowStringIntoWideCharArray);
5566         return;
5567       case SIF_WideStringIntoChar:
5568         SetFailed(FK_WideStringIntoCharArray);
5569         return;
5570       case SIF_IncompatWideStringIntoWideChar:
5571         SetFailed(FK_IncompatWideStringIntoWideChar);
5572         return;
5573       case SIF_PlainStringIntoUTF8Char:
5574         SetFailed(FK_PlainStringIntoUTF8Char);
5575         return;
5576       case SIF_UTF8StringIntoPlainChar:
5577         SetFailed(FK_UTF8StringIntoPlainChar);
5578         return;
5579       case SIF_Other:
5580         break;
5581       }
5582     }
5583
5584     // Some kinds of initialization permit an array to be initialized from
5585     // another array of the same type, and perform elementwise initialization.
5586     if (Initializer && isa<ConstantArrayType>(DestAT) &&
5587         S.Context.hasSameUnqualifiedType(Initializer->getType(),
5588                                          Entity.getType()) &&
5589         canPerformArrayCopy(Entity)) {
5590       // If source is a prvalue, use it directly.
5591       if (Initializer->getValueKind() == VK_RValue) {
5592         AddArrayInitStep(DestType, /*IsGNUExtension*/false);
5593         return;
5594       }
5595
5596       // Emit element-at-a-time copy loop.
5597       InitializedEntity Element =
5598           InitializedEntity::InitializeElement(S.Context, 0, Entity);
5599       QualType InitEltT =
5600           Context.getAsArrayType(Initializer->getType())->getElementType();
5601       OpaqueValueExpr OVE(Initializer->getExprLoc(), InitEltT,
5602                           Initializer->getValueKind(),
5603                           Initializer->getObjectKind());
5604       Expr *OVEAsExpr = &OVE;
5605       InitializeFrom(S, Element, Kind, OVEAsExpr, TopLevelOfInitList,
5606                      TreatUnavailableAsInvalid);
5607       if (!Failed())
5608         AddArrayInitLoopStep(Entity.getType(), InitEltT);
5609       return;
5610     }
5611
5612     // Note: as an GNU C extension, we allow initialization of an
5613     // array from a compound literal that creates an array of the same
5614     // type, so long as the initializer has no side effects.
5615     if (!S.getLangOpts().CPlusPlus && Initializer &&
5616         isa<CompoundLiteralExpr>(Initializer->IgnoreParens()) &&
5617         Initializer->getType()->isArrayType()) {
5618       const ArrayType *SourceAT
5619         = Context.getAsArrayType(Initializer->getType());
5620       if (!hasCompatibleArrayTypes(S.Context, DestAT, SourceAT))
5621         SetFailed(FK_ArrayTypeMismatch);
5622       else if (Initializer->HasSideEffects(S.Context))
5623         SetFailed(FK_NonConstantArrayInit);
5624       else {
5625         AddArrayInitStep(DestType, /*IsGNUExtension*/true);
5626       }
5627     }
5628     // Note: as a GNU C++ extension, we allow list-initialization of a
5629     // class member of array type from a parenthesized initializer list.
5630     else if (S.getLangOpts().CPlusPlus &&
5631              Entity.getKind() == InitializedEntity::EK_Member &&
5632              Initializer && isa<InitListExpr>(Initializer)) {
5633       TryListInitialization(S, Entity, Kind, cast<InitListExpr>(Initializer),
5634                             *this, TreatUnavailableAsInvalid);
5635       AddParenthesizedArrayInitStep(DestType);
5636     } else if (DestAT->getElementType()->isCharType())
5637       SetFailed(FK_ArrayNeedsInitListOrStringLiteral);
5638     else if (IsWideCharCompatible(DestAT->getElementType(), Context))
5639       SetFailed(FK_ArrayNeedsInitListOrWideStringLiteral);
5640     else
5641       SetFailed(FK_ArrayNeedsInitList);
5642
5643     return;
5644   }
5645
5646   // Determine whether we should consider writeback conversions for
5647   // Objective-C ARC.
5648   bool allowObjCWritebackConversion = S.getLangOpts().ObjCAutoRefCount &&
5649          Entity.isParameterKind();
5650
5651   if (TryOCLSamplerInitialization(S, *this, DestType, Initializer))
5652     return;
5653
5654   // We're at the end of the line for C: it's either a write-back conversion
5655   // or it's a C assignment. There's no need to check anything else.
5656   if (!S.getLangOpts().CPlusPlus) {
5657     // If allowed, check whether this is an Objective-C writeback conversion.
5658     if (allowObjCWritebackConversion &&
5659         tryObjCWritebackConversion(S, *this, Entity, Initializer)) {
5660       return;
5661     }
5662
5663     if (TryOCLZeroOpaqueTypeInitialization(S, *this, DestType, Initializer))
5664       return;
5665
5666     // Handle initialization in C
5667     AddCAssignmentStep(DestType);
5668     MaybeProduceObjCObject(S, *this, Entity);
5669     return;
5670   }
5671
5672   assert(S.getLangOpts().CPlusPlus);
5673
5674   //     - If the destination type is a (possibly cv-qualified) class type:
5675   if (DestType->isRecordType()) {
5676     //     - If the initialization is direct-initialization, or if it is
5677     //       copy-initialization where the cv-unqualified version of the
5678     //       source type is the same class as, or a derived class of, the
5679     //       class of the destination, constructors are considered. [...]
5680     if (Kind.getKind() == InitializationKind::IK_Direct ||
5681         (Kind.getKind() == InitializationKind::IK_Copy &&
5682          (Context.hasSameUnqualifiedType(SourceType, DestType) ||
5683           S.IsDerivedFrom(Initializer->getBeginLoc(), SourceType, DestType))))
5684       TryConstructorInitialization(S, Entity, Kind, Args,
5685                                    DestType, DestType, *this);
5686     //     - Otherwise (i.e., for the remaining copy-initialization cases),
5687     //       user-defined conversion sequences that can convert from the source
5688     //       type to the destination type or (when a conversion function is
5689     //       used) to a derived class thereof are enumerated as described in
5690     //       13.3.1.4, and the best one is chosen through overload resolution
5691     //       (13.3).
5692     else
5693       TryUserDefinedConversion(S, DestType, Kind, Initializer, *this,
5694                                TopLevelOfInitList);
5695     return;
5696   }
5697
5698   assert(Args.size() >= 1 && "Zero-argument case handled above");
5699
5700   // The remaining cases all need a source type.
5701   if (Args.size() > 1) {
5702     SetFailed(FK_TooManyInitsForScalar);
5703     return;
5704   } else if (isa<InitListExpr>(Args[0])) {
5705     SetFailed(FK_ParenthesizedListInitForScalar);
5706     return;
5707   }
5708
5709   //    - Otherwise, if the source type is a (possibly cv-qualified) class
5710   //      type, conversion functions are considered.
5711   if (!SourceType.isNull() && SourceType->isRecordType()) {
5712     // For a conversion to _Atomic(T) from either T or a class type derived
5713     // from T, initialize the T object then convert to _Atomic type.
5714     bool NeedAtomicConversion = false;
5715     if (const AtomicType *Atomic = DestType->getAs<AtomicType>()) {
5716       if (Context.hasSameUnqualifiedType(SourceType, Atomic->getValueType()) ||
5717           S.IsDerivedFrom(Initializer->getBeginLoc(), SourceType,
5718                           Atomic->getValueType())) {
5719         DestType = Atomic->getValueType();
5720         NeedAtomicConversion = true;
5721       }
5722     }
5723
5724     TryUserDefinedConversion(S, DestType, Kind, Initializer, *this,
5725                              TopLevelOfInitList);
5726     MaybeProduceObjCObject(S, *this, Entity);
5727     if (!Failed() && NeedAtomicConversion)
5728       AddAtomicConversionStep(Entity.getType());
5729     return;
5730   }
5731
5732   //    - Otherwise, the initial value of the object being initialized is the
5733   //      (possibly converted) value of the initializer expression. Standard
5734   //      conversions (Clause 4) will be used, if necessary, to convert the
5735   //      initializer expression to the cv-unqualified version of the
5736   //      destination type; no user-defined conversions are considered.
5737
5738   ImplicitConversionSequence ICS
5739     = S.TryImplicitConversion(Initializer, DestType,
5740                               /*SuppressUserConversions*/true,
5741                               /*AllowExplicitConversions*/ false,
5742                               /*InOverloadResolution*/ false,
5743                               /*CStyle=*/Kind.isCStyleOrFunctionalCast(),
5744                               allowObjCWritebackConversion);
5745
5746   if (ICS.isStandard() &&
5747       ICS.Standard.Second == ICK_Writeback_Conversion) {
5748     // Objective-C ARC writeback conversion.
5749
5750     // We should copy unless we're passing to an argument explicitly
5751     // marked 'out'.
5752     bool ShouldCopy = true;
5753     if (ParmVarDecl *Param = cast_or_null<ParmVarDecl>(Entity.getDecl()))
5754       ShouldCopy = (Param->getObjCDeclQualifier() != ParmVarDecl::OBJC_TQ_Out);
5755
5756     // If there was an lvalue adjustment, add it as a separate conversion.
5757     if (ICS.Standard.First == ICK_Array_To_Pointer ||
5758         ICS.Standard.First == ICK_Lvalue_To_Rvalue) {
5759       ImplicitConversionSequence LvalueICS;
5760       LvalueICS.setStandard();
5761       LvalueICS.Standard.setAsIdentityConversion();
5762       LvalueICS.Standard.setAllToTypes(ICS.Standard.getToType(0));
5763       LvalueICS.Standard.First = ICS.Standard.First;
5764       AddConversionSequenceStep(LvalueICS, ICS.Standard.getToType(0));
5765     }
5766
5767     AddPassByIndirectCopyRestoreStep(DestType, ShouldCopy);
5768   } else if (ICS.isBad()) {
5769     DeclAccessPair dap;
5770     if (isLibstdcxxPointerReturnFalseHack(S, Entity, Initializer)) {
5771       AddZeroInitializationStep(Entity.getType());
5772     } else if (Initializer->getType() == Context.OverloadTy &&
5773                !S.ResolveAddressOfOverloadedFunction(Initializer, DestType,
5774                                                      false, dap))
5775       SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
5776     else if (Initializer->getType()->isFunctionType() &&
5777              isExprAnUnaddressableFunction(S, Initializer))
5778       SetFailed(InitializationSequence::FK_AddressOfUnaddressableFunction);
5779     else
5780       SetFailed(InitializationSequence::FK_ConversionFailed);
5781   } else {
5782     AddConversionSequenceStep(ICS, DestType, TopLevelOfInitList);
5783
5784     MaybeProduceObjCObject(S, *this, Entity);
5785   }
5786 }
5787
5788 InitializationSequence::~InitializationSequence() {
5789   for (auto &S : Steps)
5790     S.Destroy();
5791 }
5792
5793 //===----------------------------------------------------------------------===//
5794 // Perform initialization
5795 //===----------------------------------------------------------------------===//
5796 static Sema::AssignmentAction
5797 getAssignmentAction(const InitializedEntity &Entity, bool Diagnose = false) {
5798   switch(Entity.getKind()) {
5799   case InitializedEntity::EK_Variable:
5800   case InitializedEntity::EK_New:
5801   case InitializedEntity::EK_Exception:
5802   case InitializedEntity::EK_Base:
5803   case InitializedEntity::EK_Delegating:
5804     return Sema::AA_Initializing;
5805
5806   case InitializedEntity::EK_Parameter:
5807     if (Entity.getDecl() &&
5808         isa<ObjCMethodDecl>(Entity.getDecl()->getDeclContext()))
5809       return Sema::AA_Sending;
5810
5811     return Sema::AA_Passing;
5812
5813   case InitializedEntity::EK_Parameter_CF_Audited:
5814     if (Entity.getDecl() &&
5815       isa<ObjCMethodDecl>(Entity.getDecl()->getDeclContext()))
5816       return Sema::AA_Sending;
5817
5818     return !Diagnose ? Sema::AA_Passing : Sema::AA_Passing_CFAudited;
5819
5820   case InitializedEntity::EK_Result:
5821   case InitializedEntity::EK_StmtExprResult: // FIXME: Not quite right.
5822     return Sema::AA_Returning;
5823
5824   case InitializedEntity::EK_Temporary:
5825   case InitializedEntity::EK_RelatedResult:
5826     // FIXME: Can we tell apart casting vs. converting?
5827     return Sema::AA_Casting;
5828
5829   case InitializedEntity::EK_Member:
5830   case InitializedEntity::EK_Binding:
5831   case InitializedEntity::EK_ArrayElement:
5832   case InitializedEntity::EK_VectorElement:
5833   case InitializedEntity::EK_ComplexElement:
5834   case InitializedEntity::EK_BlockElement:
5835   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5836   case InitializedEntity::EK_LambdaCapture:
5837   case InitializedEntity::EK_CompoundLiteralInit:
5838     return Sema::AA_Initializing;
5839   }
5840
5841   llvm_unreachable("Invalid EntityKind!");
5842 }
5843
5844 /// Whether we should bind a created object as a temporary when
5845 /// initializing the given entity.
5846 static bool shouldBindAsTemporary(const InitializedEntity &Entity) {
5847   switch (Entity.getKind()) {
5848   case InitializedEntity::EK_ArrayElement:
5849   case InitializedEntity::EK_Member:
5850   case InitializedEntity::EK_Result:
5851   case InitializedEntity::EK_StmtExprResult:
5852   case InitializedEntity::EK_New:
5853   case InitializedEntity::EK_Variable:
5854   case InitializedEntity::EK_Base:
5855   case InitializedEntity::EK_Delegating:
5856   case InitializedEntity::EK_VectorElement:
5857   case InitializedEntity::EK_ComplexElement:
5858   case InitializedEntity::EK_Exception:
5859   case InitializedEntity::EK_BlockElement:
5860   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5861   case InitializedEntity::EK_LambdaCapture:
5862   case InitializedEntity::EK_CompoundLiteralInit:
5863     return false;
5864
5865   case InitializedEntity::EK_Parameter:
5866   case InitializedEntity::EK_Parameter_CF_Audited:
5867   case InitializedEntity::EK_Temporary:
5868   case InitializedEntity::EK_RelatedResult:
5869   case InitializedEntity::EK_Binding:
5870     return true;
5871   }
5872
5873   llvm_unreachable("missed an InitializedEntity kind?");
5874 }
5875
5876 /// Whether the given entity, when initialized with an object
5877 /// created for that initialization, requires destruction.
5878 static bool shouldDestroyEntity(const InitializedEntity &Entity) {
5879   switch (Entity.getKind()) {
5880     case InitializedEntity::EK_Result:
5881     case InitializedEntity::EK_StmtExprResult:
5882     case InitializedEntity::EK_New:
5883     case InitializedEntity::EK_Base:
5884     case InitializedEntity::EK_Delegating:
5885     case InitializedEntity::EK_VectorElement:
5886     case InitializedEntity::EK_ComplexElement:
5887     case InitializedEntity::EK_BlockElement:
5888     case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5889     case InitializedEntity::EK_LambdaCapture:
5890       return false;
5891
5892     case InitializedEntity::EK_Member:
5893     case InitializedEntity::EK_Binding:
5894     case InitializedEntity::EK_Variable:
5895     case InitializedEntity::EK_Parameter:
5896     case InitializedEntity::EK_Parameter_CF_Audited:
5897     case InitializedEntity::EK_Temporary:
5898     case InitializedEntity::EK_ArrayElement:
5899     case InitializedEntity::EK_Exception:
5900     case InitializedEntity::EK_CompoundLiteralInit:
5901     case InitializedEntity::EK_RelatedResult:
5902       return true;
5903   }
5904
5905   llvm_unreachable("missed an InitializedEntity kind?");
5906 }
5907
5908 /// Get the location at which initialization diagnostics should appear.
5909 static SourceLocation getInitializationLoc(const InitializedEntity &Entity,
5910                                            Expr *Initializer) {
5911   switch (Entity.getKind()) {
5912   case InitializedEntity::EK_Result:
5913   case InitializedEntity::EK_StmtExprResult:
5914     return Entity.getReturnLoc();
5915
5916   case InitializedEntity::EK_Exception:
5917     return Entity.getThrowLoc();
5918
5919   case InitializedEntity::EK_Variable:
5920   case InitializedEntity::EK_Binding:
5921     return Entity.getDecl()->getLocation();
5922
5923   case InitializedEntity::EK_LambdaCapture:
5924     return Entity.getCaptureLoc();
5925
5926   case InitializedEntity::EK_ArrayElement:
5927   case InitializedEntity::EK_Member:
5928   case InitializedEntity::EK_Parameter:
5929   case InitializedEntity::EK_Parameter_CF_Audited:
5930   case InitializedEntity::EK_Temporary:
5931   case InitializedEntity::EK_New:
5932   case InitializedEntity::EK_Base:
5933   case InitializedEntity::EK_Delegating:
5934   case InitializedEntity::EK_VectorElement:
5935   case InitializedEntity::EK_ComplexElement:
5936   case InitializedEntity::EK_BlockElement:
5937   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5938   case InitializedEntity::EK_CompoundLiteralInit:
5939   case InitializedEntity::EK_RelatedResult:
5940     return Initializer->getBeginLoc();
5941   }
5942   llvm_unreachable("missed an InitializedEntity kind?");
5943 }
5944
5945 /// Make a (potentially elidable) temporary copy of the object
5946 /// provided by the given initializer by calling the appropriate copy
5947 /// constructor.
5948 ///
5949 /// \param S The Sema object used for type-checking.
5950 ///
5951 /// \param T The type of the temporary object, which must either be
5952 /// the type of the initializer expression or a superclass thereof.
5953 ///
5954 /// \param Entity The entity being initialized.
5955 ///
5956 /// \param CurInit The initializer expression.
5957 ///
5958 /// \param IsExtraneousCopy Whether this is an "extraneous" copy that
5959 /// is permitted in C++03 (but not C++0x) when binding a reference to
5960 /// an rvalue.
5961 ///
5962 /// \returns An expression that copies the initializer expression into
5963 /// a temporary object, or an error expression if a copy could not be
5964 /// created.
5965 static ExprResult CopyObject(Sema &S,
5966                              QualType T,
5967                              const InitializedEntity &Entity,
5968                              ExprResult CurInit,
5969                              bool IsExtraneousCopy) {
5970   if (CurInit.isInvalid())
5971     return CurInit;
5972   // Determine which class type we're copying to.
5973   Expr *CurInitExpr = (Expr *)CurInit.get();
5974   CXXRecordDecl *Class = nullptr;
5975   if (const RecordType *Record = T->getAs<RecordType>())
5976     Class = cast<CXXRecordDecl>(Record->getDecl());
5977   if (!Class)
5978     return CurInit;
5979
5980   SourceLocation Loc = getInitializationLoc(Entity, CurInit.get());
5981
5982   // Make sure that the type we are copying is complete.
5983   if (S.RequireCompleteType(Loc, T, diag::err_temp_copy_incomplete))
5984     return CurInit;
5985
5986   // Perform overload resolution using the class's constructors. Per
5987   // C++11 [dcl.init]p16, second bullet for class types, this initialization
5988   // is direct-initialization.
5989   OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
5990   DeclContext::lookup_result Ctors = S.LookupConstructors(Class);
5991
5992   OverloadCandidateSet::iterator Best;
5993   switch (ResolveConstructorOverload(
5994       S, Loc, CurInitExpr, CandidateSet, T, Ctors, Best,
5995       /*CopyInitializing=*/false, /*AllowExplicit=*/true,
5996       /*OnlyListConstructors=*/false, /*IsListInit=*/false,
5997       /*SecondStepOfCopyInit=*/true)) {
5998   case OR_Success:
5999     break;
6000
6001   case OR_No_Viable_Function:
6002     CandidateSet.NoteCandidates(
6003         PartialDiagnosticAt(
6004             Loc, S.PDiag(IsExtraneousCopy && !S.isSFINAEContext()
6005                              ? diag::ext_rvalue_to_reference_temp_copy_no_viable
6006                              : diag::err_temp_copy_no_viable)
6007                      << (int)Entity.getKind() << CurInitExpr->getType()
6008                      << CurInitExpr->getSourceRange()),
6009         S, OCD_AllCandidates, CurInitExpr);
6010     if (!IsExtraneousCopy || S.isSFINAEContext())
6011       return ExprError();
6012     return CurInit;
6013
6014   case OR_Ambiguous:
6015     CandidateSet.NoteCandidates(
6016         PartialDiagnosticAt(Loc, S.PDiag(diag::err_temp_copy_ambiguous)
6017                                      << (int)Entity.getKind()
6018                                      << CurInitExpr->getType()
6019                                      << CurInitExpr->getSourceRange()),
6020         S, OCD_ViableCandidates, CurInitExpr);
6021     return ExprError();
6022
6023   case OR_Deleted:
6024     S.Diag(Loc, diag::err_temp_copy_deleted)
6025       << (int)Entity.getKind() << CurInitExpr->getType()
6026       << CurInitExpr->getSourceRange();
6027     S.NoteDeletedFunction(Best->Function);
6028     return ExprError();
6029   }
6030
6031   bool HadMultipleCandidates = CandidateSet.size() > 1;
6032
6033   CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(Best->Function);
6034   SmallVector<Expr*, 8> ConstructorArgs;
6035   CurInit.get(); // Ownership transferred into MultiExprArg, below.
6036
6037   S.CheckConstructorAccess(Loc, Constructor, Best->FoundDecl, Entity,
6038                            IsExtraneousCopy);
6039
6040   if (IsExtraneousCopy) {
6041     // If this is a totally extraneous copy for C++03 reference
6042     // binding purposes, just return the original initialization
6043     // expression. We don't generate an (elided) copy operation here
6044     // because doing so would require us to pass down a flag to avoid
6045     // infinite recursion, where each step adds another extraneous,
6046     // elidable copy.
6047
6048     // Instantiate the default arguments of any extra parameters in
6049     // the selected copy constructor, as if we were going to create a
6050     // proper call to the copy constructor.
6051     for (unsigned I = 1, N = Constructor->getNumParams(); I != N; ++I) {
6052       ParmVarDecl *Parm = Constructor->getParamDecl(I);
6053       if (S.RequireCompleteType(Loc, Parm->getType(),
6054                                 diag::err_call_incomplete_argument))
6055         break;
6056
6057       // Build the default argument expression; we don't actually care
6058       // if this succeeds or not, because this routine will complain
6059       // if there was a problem.
6060       S.BuildCXXDefaultArgExpr(Loc, Constructor, Parm);
6061     }
6062
6063     return CurInitExpr;
6064   }
6065
6066   // Determine the arguments required to actually perform the
6067   // constructor call (we might have derived-to-base conversions, or
6068   // the copy constructor may have default arguments).
6069   if (S.CompleteConstructorCall(Constructor, CurInitExpr, Loc, ConstructorArgs))
6070     return ExprError();
6071
6072   // C++0x [class.copy]p32:
6073   //   When certain criteria are met, an implementation is allowed to
6074   //   omit the copy/move construction of a class object, even if the
6075   //   copy/move constructor and/or destructor for the object have
6076   //   side effects. [...]
6077   //     - when a temporary class object that has not been bound to a
6078   //       reference (12.2) would be copied/moved to a class object
6079   //       with the same cv-unqualified type, the copy/move operation
6080   //       can be omitted by constructing the temporary object
6081   //       directly into the target of the omitted copy/move
6082   //
6083   // Note that the other three bullets are handled elsewhere. Copy
6084   // elision for return statements and throw expressions are handled as part
6085   // of constructor initialization, while copy elision for exception handlers
6086   // is handled by the run-time.
6087   //
6088   // FIXME: If the function parameter is not the same type as the temporary, we
6089   // should still be able to elide the copy, but we don't have a way to
6090   // represent in the AST how much should be elided in this case.
6091   bool Elidable =
6092       CurInitExpr->isTemporaryObject(S.Context, Class) &&
6093       S.Context.hasSameUnqualifiedType(
6094           Best->Function->getParamDecl(0)->getType().getNonReferenceType(),
6095           CurInitExpr->getType());
6096
6097   // Actually perform the constructor call.
6098   CurInit = S.BuildCXXConstructExpr(Loc, T, Best->FoundDecl, Constructor,
6099                                     Elidable,
6100                                     ConstructorArgs,
6101                                     HadMultipleCandidates,
6102                                     /*ListInit*/ false,
6103                                     /*StdInitListInit*/ false,
6104                                     /*ZeroInit*/ false,
6105                                     CXXConstructExpr::CK_Complete,
6106                                     SourceRange());
6107
6108   // If we're supposed to bind temporaries, do so.
6109   if (!CurInit.isInvalid() && shouldBindAsTemporary(Entity))
6110     CurInit = S.MaybeBindToTemporary(CurInit.getAs<Expr>());
6111   return CurInit;
6112 }
6113
6114 /// Check whether elidable copy construction for binding a reference to
6115 /// a temporary would have succeeded if we were building in C++98 mode, for
6116 /// -Wc++98-compat.
6117 static void CheckCXX98CompatAccessibleCopy(Sema &S,
6118                                            const InitializedEntity &Entity,
6119                                            Expr *CurInitExpr) {
6120   assert(S.getLangOpts().CPlusPlus11);
6121
6122   const RecordType *Record = CurInitExpr->getType()->getAs<RecordType>();
6123   if (!Record)
6124     return;
6125
6126   SourceLocation Loc = getInitializationLoc(Entity, CurInitExpr);
6127   if (S.Diags.isIgnored(diag::warn_cxx98_compat_temp_copy, Loc))
6128     return;
6129
6130   // Find constructors which would have been considered.
6131   OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
6132   DeclContext::lookup_result Ctors =
6133       S.LookupConstructors(cast<CXXRecordDecl>(Record->getDecl()));
6134
6135   // Perform overload resolution.
6136   OverloadCandidateSet::iterator Best;
6137   OverloadingResult OR = ResolveConstructorOverload(
6138       S, Loc, CurInitExpr, CandidateSet, CurInitExpr->getType(), Ctors, Best,
6139       /*CopyInitializing=*/false, /*AllowExplicit=*/true,
6140       /*OnlyListConstructors=*/false, /*IsListInit=*/false,
6141       /*SecondStepOfCopyInit=*/true);
6142
6143   PartialDiagnostic Diag = S.PDiag(diag::warn_cxx98_compat_temp_copy)
6144     << OR << (int)Entity.getKind() << CurInitExpr->getType()
6145     << CurInitExpr->getSourceRange();
6146
6147   switch (OR) {
6148   case OR_Success:
6149     S.CheckConstructorAccess(Loc, cast<CXXConstructorDecl>(Best->Function),
6150                              Best->FoundDecl, Entity, Diag);
6151     // FIXME: Check default arguments as far as that's possible.
6152     break;
6153
6154   case OR_No_Viable_Function:
6155     CandidateSet.NoteCandidates(PartialDiagnosticAt(Loc, Diag), S,
6156                                 OCD_AllCandidates, CurInitExpr);
6157     break;
6158
6159   case OR_Ambiguous:
6160     CandidateSet.NoteCandidates(PartialDiagnosticAt(Loc, Diag), S,
6161                                 OCD_ViableCandidates, CurInitExpr);
6162     break;
6163
6164   case OR_Deleted:
6165     S.Diag(Loc, Diag);
6166     S.NoteDeletedFunction(Best->Function);
6167     break;
6168   }
6169 }
6170
6171 void InitializationSequence::PrintInitLocationNote(Sema &S,
6172                                               const InitializedEntity &Entity) {
6173   if (Entity.isParameterKind() && Entity.getDecl()) {
6174     if (Entity.getDecl()->getLocation().isInvalid())
6175       return;
6176
6177     if (Entity.getDecl()->getDeclName())
6178       S.Diag(Entity.getDecl()->getLocation(), diag::note_parameter_named_here)
6179         << Entity.getDecl()->getDeclName();
6180     else
6181       S.Diag(Entity.getDecl()->getLocation(), diag::note_parameter_here);
6182   }
6183   else if (Entity.getKind() == InitializedEntity::EK_RelatedResult &&
6184            Entity.getMethodDecl())
6185     S.Diag(Entity.getMethodDecl()->getLocation(),
6186            diag::note_method_return_type_change)
6187       << Entity.getMethodDecl()->getDeclName();
6188 }
6189
6190 /// Returns true if the parameters describe a constructor initialization of
6191 /// an explicit temporary object, e.g. "Point(x, y)".
6192 static bool isExplicitTemporary(const InitializedEntity &Entity,
6193                                 const InitializationKind &Kind,
6194                                 unsigned NumArgs) {
6195   switch (Entity.getKind()) {
6196   case InitializedEntity::EK_Temporary:
6197   case InitializedEntity::EK_CompoundLiteralInit:
6198   case InitializedEntity::EK_RelatedResult:
6199     break;
6200   default:
6201     return false;
6202   }
6203
6204   switch (Kind.getKind()) {
6205   case InitializationKind::IK_DirectList:
6206     return true;
6207   // FIXME: Hack to work around cast weirdness.
6208   case InitializationKind::IK_Direct:
6209   case InitializationKind::IK_Value:
6210     return NumArgs != 1;
6211   default:
6212     return false;
6213   }
6214 }
6215
6216 static ExprResult
6217 PerformConstructorInitialization(Sema &S,
6218                                  const InitializedEntity &Entity,
6219                                  const InitializationKind &Kind,
6220                                  MultiExprArg Args,
6221                                  const InitializationSequence::Step& Step,
6222                                  bool &ConstructorInitRequiresZeroInit,
6223                                  bool IsListInitialization,
6224                                  bool IsStdInitListInitialization,
6225                                  SourceLocation LBraceLoc,
6226                                  SourceLocation RBraceLoc) {
6227   unsigned NumArgs = Args.size();
6228   CXXConstructorDecl *Constructor
6229     = cast<CXXConstructorDecl>(Step.Function.Function);
6230   bool HadMultipleCandidates = Step.Function.HadMultipleCandidates;
6231
6232   // Build a call to the selected constructor.
6233   SmallVector<Expr*, 8> ConstructorArgs;
6234   SourceLocation Loc = (Kind.isCopyInit() && Kind.getEqualLoc().isValid())
6235                          ? Kind.getEqualLoc()
6236                          : Kind.getLocation();
6237
6238   if (Kind.getKind() == InitializationKind::IK_Default) {
6239     // Force even a trivial, implicit default constructor to be
6240     // semantically checked. We do this explicitly because we don't build
6241     // the definition for completely trivial constructors.
6242     assert(Constructor->getParent() && "No parent class for constructor.");
6243     if (Constructor->isDefaulted() && Constructor->isDefaultConstructor() &&
6244         Constructor->isTrivial() && !Constructor->isUsed(false))
6245       S.DefineImplicitDefaultConstructor(Loc, Constructor);
6246   }
6247
6248   ExprResult CurInit((Expr *)nullptr);
6249
6250   // C++ [over.match.copy]p1:
6251   //   - When initializing a temporary to be bound to the first parameter
6252   //     of a constructor that takes a reference to possibly cv-qualified
6253   //     T as its first argument, called with a single argument in the
6254   //     context of direct-initialization, explicit conversion functions
6255   //     are also considered.
6256   bool AllowExplicitConv =
6257       Kind.AllowExplicit() && !Kind.isCopyInit() && Args.size() == 1 &&
6258       hasCopyOrMoveCtorParam(S.Context,
6259                              getConstructorInfo(Step.Function.FoundDecl));
6260
6261   // Determine the arguments required to actually perform the constructor
6262   // call.
6263   if (S.CompleteConstructorCall(Constructor, Args,
6264                                 Loc, ConstructorArgs,
6265                                 AllowExplicitConv,
6266                                 IsListInitialization))
6267     return ExprError();
6268
6269
6270   if (isExplicitTemporary(Entity, Kind, NumArgs)) {
6271     // An explicitly-constructed temporary, e.g., X(1, 2).
6272     if (S.DiagnoseUseOfDecl(Constructor, Loc))
6273       return ExprError();
6274
6275     TypeSourceInfo *TSInfo = Entity.getTypeSourceInfo();
6276     if (!TSInfo)
6277       TSInfo = S.Context.getTrivialTypeSourceInfo(Entity.getType(), Loc);
6278     SourceRange ParenOrBraceRange =
6279         (Kind.getKind() == InitializationKind::IK_DirectList)
6280         ? SourceRange(LBraceLoc, RBraceLoc)
6281         : Kind.getParenOrBraceRange();
6282
6283     if (auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(
6284             Step.Function.FoundDecl.getDecl())) {
6285       Constructor = S.findInheritingConstructor(Loc, Constructor, Shadow);
6286       if (S.DiagnoseUseOfDecl(Constructor, Loc))
6287         return ExprError();
6288     }
6289     S.MarkFunctionReferenced(Loc, Constructor);
6290
6291     CurInit = CXXTemporaryObjectExpr::Create(
6292         S.Context, Constructor,
6293         Entity.getType().getNonLValueExprType(S.Context), TSInfo,
6294         ConstructorArgs, ParenOrBraceRange, HadMultipleCandidates,
6295         IsListInitialization, IsStdInitListInitialization,
6296         ConstructorInitRequiresZeroInit);
6297   } else {
6298     CXXConstructExpr::ConstructionKind ConstructKind =
6299       CXXConstructExpr::CK_Complete;
6300
6301     if (Entity.getKind() == InitializedEntity::EK_Base) {
6302       ConstructKind = Entity.getBaseSpecifier()->isVirtual() ?
6303         CXXConstructExpr::CK_VirtualBase :
6304         CXXConstructExpr::CK_NonVirtualBase;
6305     } else if (Entity.getKind() == InitializedEntity::EK_Delegating) {
6306       ConstructKind = CXXConstructExpr::CK_Delegating;
6307     }
6308
6309     // Only get the parenthesis or brace range if it is a list initialization or
6310     // direct construction.
6311     SourceRange ParenOrBraceRange;
6312     if (IsListInitialization)
6313       ParenOrBraceRange = SourceRange(LBraceLoc, RBraceLoc);
6314     else if (Kind.getKind() == InitializationKind::IK_Direct)
6315       ParenOrBraceRange = Kind.getParenOrBraceRange();
6316
6317     // If the entity allows NRVO, mark the construction as elidable
6318     // unconditionally.
6319     if (Entity.allowsNRVO())
6320       CurInit = S.BuildCXXConstructExpr(Loc, Step.Type,
6321                                         Step.Function.FoundDecl,
6322                                         Constructor, /*Elidable=*/true,
6323                                         ConstructorArgs,
6324                                         HadMultipleCandidates,
6325                                         IsListInitialization,
6326                                         IsStdInitListInitialization,
6327                                         ConstructorInitRequiresZeroInit,
6328                                         ConstructKind,
6329                                         ParenOrBraceRange);
6330     else
6331       CurInit = S.BuildCXXConstructExpr(Loc, Step.Type,
6332                                         Step.Function.FoundDecl,
6333                                         Constructor,
6334                                         ConstructorArgs,
6335                                         HadMultipleCandidates,
6336                                         IsListInitialization,
6337                                         IsStdInitListInitialization,
6338                                         ConstructorInitRequiresZeroInit,
6339                                         ConstructKind,
6340                                         ParenOrBraceRange);
6341   }
6342   if (CurInit.isInvalid())
6343     return ExprError();
6344
6345   // Only check access if all of that succeeded.
6346   S.CheckConstructorAccess(Loc, Constructor, Step.Function.FoundDecl, Entity);
6347   if (S.DiagnoseUseOfDecl(Step.Function.FoundDecl, Loc))
6348     return ExprError();
6349
6350   if (const ArrayType *AT = S.Context.getAsArrayType(Entity.getType()))
6351     if (checkDestructorReference(S.Context.getBaseElementType(AT), Loc, S))
6352       return ExprError();
6353
6354   if (shouldBindAsTemporary(Entity))
6355     CurInit = S.MaybeBindToTemporary(CurInit.get());
6356
6357   return CurInit;
6358 }
6359
6360 namespace {
6361 enum LifetimeKind {
6362   /// The lifetime of a temporary bound to this entity ends at the end of the
6363   /// full-expression, and that's (probably) fine.
6364   LK_FullExpression,
6365
6366   /// The lifetime of a temporary bound to this entity is extended to the
6367   /// lifeitme of the entity itself.
6368   LK_Extended,
6369
6370   /// The lifetime of a temporary bound to this entity probably ends too soon,
6371   /// because the entity is allocated in a new-expression.
6372   LK_New,
6373
6374   /// The lifetime of a temporary bound to this entity ends too soon, because
6375   /// the entity is a return object.
6376   LK_Return,
6377
6378   /// The lifetime of a temporary bound to this entity ends too soon, because
6379   /// the entity is the result of a statement expression.
6380   LK_StmtExprResult,
6381
6382   /// This is a mem-initializer: if it would extend a temporary (other than via
6383   /// a default member initializer), the program is ill-formed.
6384   LK_MemInitializer,
6385 };
6386 using LifetimeResult =
6387     llvm::PointerIntPair<const InitializedEntity *, 3, LifetimeKind>;
6388 }
6389
6390 /// Determine the declaration which an initialized entity ultimately refers to,
6391 /// for the purpose of lifetime-extending a temporary bound to a reference in
6392 /// the initialization of \p Entity.
6393 static LifetimeResult getEntityLifetime(
6394     const InitializedEntity *Entity,
6395     const InitializedEntity *InitField = nullptr) {
6396   // C++11 [class.temporary]p5:
6397   switch (Entity->getKind()) {
6398   case InitializedEntity::EK_Variable:
6399     //   The temporary [...] persists for the lifetime of the reference
6400     return {Entity, LK_Extended};
6401
6402   case InitializedEntity::EK_Member:
6403     // For subobjects, we look at the complete object.
6404     if (Entity->getParent())
6405       return getEntityLifetime(Entity->getParent(), Entity);
6406
6407     //   except:
6408     // C++17 [class.base.init]p8:
6409     //   A temporary expression bound to a reference member in a
6410     //   mem-initializer is ill-formed.
6411     // C++17 [class.base.init]p11:
6412     //   A temporary expression bound to a reference member from a
6413     //   default member initializer is ill-formed.
6414     //
6415     // The context of p11 and its example suggest that it's only the use of a
6416     // default member initializer from a constructor that makes the program
6417     // ill-formed, not its mere existence, and that it can even be used by
6418     // aggregate initialization.
6419     return {Entity, Entity->isDefaultMemberInitializer() ? LK_Extended
6420                                                          : LK_MemInitializer};
6421
6422   case InitializedEntity::EK_Binding:
6423     // Per [dcl.decomp]p3, the binding is treated as a variable of reference
6424     // type.
6425     return {Entity, LK_Extended};
6426
6427   case InitializedEntity::EK_Parameter:
6428   case InitializedEntity::EK_Parameter_CF_Audited:
6429     //   -- A temporary bound to a reference parameter in a function call
6430     //      persists until the completion of the full-expression containing
6431     //      the call.
6432     return {nullptr, LK_FullExpression};
6433
6434   case InitializedEntity::EK_Result:
6435     //   -- The lifetime of a temporary bound to the returned value in a
6436     //      function return statement is not extended; the temporary is
6437     //      destroyed at the end of the full-expression in the return statement.
6438     return {nullptr, LK_Return};
6439
6440   case InitializedEntity::EK_StmtExprResult:
6441     // FIXME: Should we lifetime-extend through the result of a statement
6442     // expression?
6443     return {nullptr, LK_StmtExprResult};
6444
6445   case InitializedEntity::EK_New:
6446     //   -- A temporary bound to a reference in a new-initializer persists
6447     //      until the completion of the full-expression containing the
6448     //      new-initializer.
6449     return {nullptr, LK_New};
6450
6451   case InitializedEntity::EK_Temporary:
6452   case InitializedEntity::EK_CompoundLiteralInit:
6453   case InitializedEntity::EK_RelatedResult:
6454     // We don't yet know the storage duration of the surrounding temporary.
6455     // Assume it's got full-expression duration for now, it will patch up our
6456     // storage duration if that's not correct.
6457     return {nullptr, LK_FullExpression};
6458
6459   case InitializedEntity::EK_ArrayElement:
6460     // For subobjects, we look at the complete object.
6461     return getEntityLifetime(Entity->getParent(), InitField);
6462
6463   case InitializedEntity::EK_Base:
6464     // For subobjects, we look at the complete object.
6465     if (Entity->getParent())
6466       return getEntityLifetime(Entity->getParent(), InitField);
6467     return {InitField, LK_MemInitializer};
6468
6469   case InitializedEntity::EK_Delegating:
6470     // We can reach this case for aggregate initialization in a constructor:
6471     //   struct A { int &&r; };
6472     //   struct B : A { B() : A{0} {} };
6473     // In this case, use the outermost field decl as the context.
6474     return {InitField, LK_MemInitializer};
6475
6476   case InitializedEntity::EK_BlockElement:
6477   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
6478   case InitializedEntity::EK_LambdaCapture:
6479   case InitializedEntity::EK_VectorElement:
6480   case InitializedEntity::EK_ComplexElement:
6481     return {nullptr, LK_FullExpression};
6482
6483   case InitializedEntity::EK_Exception:
6484     // FIXME: Can we diagnose lifetime problems with exceptions?
6485     return {nullptr, LK_FullExpression};
6486   }
6487   llvm_unreachable("unknown entity kind");
6488 }
6489
6490 namespace {
6491 enum ReferenceKind {
6492   /// Lifetime would be extended by a reference binding to a temporary.
6493   RK_ReferenceBinding,
6494   /// Lifetime would be extended by a std::initializer_list object binding to
6495   /// its backing array.
6496   RK_StdInitializerList,
6497 };
6498
6499 /// A temporary or local variable. This will be one of:
6500 ///  * A MaterializeTemporaryExpr.
6501 ///  * A DeclRefExpr whose declaration is a local.
6502 ///  * An AddrLabelExpr.
6503 ///  * A BlockExpr for a block with captures.
6504 using Local = Expr*;
6505
6506 /// Expressions we stepped over when looking for the local state. Any steps
6507 /// that would inhibit lifetime extension or take us out of subexpressions of
6508 /// the initializer are included.
6509 struct IndirectLocalPathEntry {
6510   enum EntryKind {
6511     DefaultInit,
6512     AddressOf,
6513     VarInit,
6514     LValToRVal,
6515     LifetimeBoundCall,
6516   } Kind;
6517   Expr *E;
6518   const Decl *D = nullptr;
6519   IndirectLocalPathEntry() {}
6520   IndirectLocalPathEntry(EntryKind K, Expr *E) : Kind(K), E(E) {}
6521   IndirectLocalPathEntry(EntryKind K, Expr *E, const Decl *D)
6522       : Kind(K), E(E), D(D) {}
6523 };
6524
6525 using IndirectLocalPath = llvm::SmallVectorImpl<IndirectLocalPathEntry>;
6526
6527 struct RevertToOldSizeRAII {
6528   IndirectLocalPath &Path;
6529   unsigned OldSize = Path.size();
6530   RevertToOldSizeRAII(IndirectLocalPath &Path) : Path(Path) {}
6531   ~RevertToOldSizeRAII() { Path.resize(OldSize); }
6532 };
6533
6534 using LocalVisitor = llvm::function_ref<bool(IndirectLocalPath &Path, Local L,
6535                                              ReferenceKind RK)>;
6536 }
6537
6538 static bool isVarOnPath(IndirectLocalPath &Path, VarDecl *VD) {
6539   for (auto E : Path)
6540     if (E.Kind == IndirectLocalPathEntry::VarInit && E.D == VD)
6541       return true;
6542   return false;
6543 }
6544
6545 static bool pathContainsInit(IndirectLocalPath &Path) {
6546   return llvm::any_of(Path, [=](IndirectLocalPathEntry E) {
6547     return E.Kind == IndirectLocalPathEntry::DefaultInit ||
6548            E.Kind == IndirectLocalPathEntry::VarInit;
6549   });
6550 }
6551
6552 static void visitLocalsRetainedByInitializer(IndirectLocalPath &Path,
6553                                              Expr *Init, LocalVisitor Visit,
6554                                              bool RevisitSubinits);
6555
6556 static void visitLocalsRetainedByReferenceBinding(IndirectLocalPath &Path,
6557                                                   Expr *Init, ReferenceKind RK,
6558                                                   LocalVisitor Visit);
6559
6560 static bool implicitObjectParamIsLifetimeBound(const FunctionDecl *FD) {
6561   const TypeSourceInfo *TSI = FD->getTypeSourceInfo();
6562   if (!TSI)
6563     return false;
6564   // Don't declare this variable in the second operand of the for-statement;
6565   // GCC miscompiles that by ending its lifetime before evaluating the
6566   // third operand. See gcc.gnu.org/PR86769.
6567   AttributedTypeLoc ATL;
6568   for (TypeLoc TL = TSI->getTypeLoc();
6569        (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
6570        TL = ATL.getModifiedLoc()) {
6571     if (ATL.getAttrAs<LifetimeBoundAttr>())
6572       return true;
6573   }
6574   return false;
6575 }
6576
6577 static void visitLifetimeBoundArguments(IndirectLocalPath &Path, Expr *Call,
6578                                         LocalVisitor Visit) {
6579   const FunctionDecl *Callee;
6580   ArrayRef<Expr*> Args;
6581
6582   if (auto *CE = dyn_cast<CallExpr>(Call)) {
6583     Callee = CE->getDirectCallee();
6584     Args = llvm::makeArrayRef(CE->getArgs(), CE->getNumArgs());
6585   } else {
6586     auto *CCE = cast<CXXConstructExpr>(Call);
6587     Callee = CCE->getConstructor();
6588     Args = llvm::makeArrayRef(CCE->getArgs(), CCE->getNumArgs());
6589   }
6590   if (!Callee)
6591     return;
6592
6593   Expr *ObjectArg = nullptr;
6594   if (isa<CXXOperatorCallExpr>(Call) && Callee->isCXXInstanceMember()) {
6595     ObjectArg = Args[0];
6596     Args = Args.slice(1);
6597   } else if (auto *MCE = dyn_cast<CXXMemberCallExpr>(Call)) {
6598     ObjectArg = MCE->getImplicitObjectArgument();
6599   }
6600
6601   auto VisitLifetimeBoundArg = [&](const Decl *D, Expr *Arg) {
6602     Path.push_back({IndirectLocalPathEntry::LifetimeBoundCall, Arg, D});
6603     if (Arg->isGLValue())
6604       visitLocalsRetainedByReferenceBinding(Path, Arg, RK_ReferenceBinding,
6605                                             Visit);
6606     else
6607       visitLocalsRetainedByInitializer(Path, Arg, Visit, true);
6608     Path.pop_back();
6609   };
6610
6611   if (ObjectArg && implicitObjectParamIsLifetimeBound(Callee))
6612     VisitLifetimeBoundArg(Callee, ObjectArg);
6613
6614   for (unsigned I = 0,
6615                 N = std::min<unsigned>(Callee->getNumParams(), Args.size());
6616        I != N; ++I) {
6617     if (Callee->getParamDecl(I)->hasAttr<LifetimeBoundAttr>())
6618       VisitLifetimeBoundArg(Callee->getParamDecl(I), Args[I]);
6619   }
6620 }
6621
6622 /// Visit the locals that would be reachable through a reference bound to the
6623 /// glvalue expression \c Init.
6624 static void visitLocalsRetainedByReferenceBinding(IndirectLocalPath &Path,
6625                                                   Expr *Init, ReferenceKind RK,
6626                                                   LocalVisitor Visit) {
6627   RevertToOldSizeRAII RAII(Path);
6628
6629   // Walk past any constructs which we can lifetime-extend across.
6630   Expr *Old;
6631   do {
6632     Old = Init;
6633
6634     if (auto *FE = dyn_cast<FullExpr>(Init))
6635       Init = FE->getSubExpr();
6636
6637     if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
6638       // If this is just redundant braces around an initializer, step over it.
6639       if (ILE->isTransparent())
6640         Init = ILE->getInit(0);
6641     }
6642
6643     // Step over any subobject adjustments; we may have a materialized
6644     // temporary inside them.
6645     Init = const_cast<Expr *>(Init->skipRValueSubobjectAdjustments());
6646
6647     // Per current approach for DR1376, look through casts to reference type
6648     // when performing lifetime extension.
6649     if (CastExpr *CE = dyn_cast<CastExpr>(Init))
6650       if (CE->getSubExpr()->isGLValue())
6651         Init = CE->getSubExpr();
6652
6653     // Per the current approach for DR1299, look through array element access
6654     // on array glvalues when performing lifetime extension.
6655     if (auto *ASE = dyn_cast<ArraySubscriptExpr>(Init)) {
6656       Init = ASE->getBase();
6657       auto *ICE = dyn_cast<ImplicitCastExpr>(Init);
6658       if (ICE && ICE->getCastKind() == CK_ArrayToPointerDecay)
6659         Init = ICE->getSubExpr();
6660       else
6661         // We can't lifetime extend through this but we might still find some
6662         // retained temporaries.
6663         return visitLocalsRetainedByInitializer(Path, Init, Visit, true);
6664     }
6665
6666     // Step into CXXDefaultInitExprs so we can diagnose cases where a
6667     // constructor inherits one as an implicit mem-initializer.
6668     if (auto *DIE = dyn_cast<CXXDefaultInitExpr>(Init)) {
6669       Path.push_back(
6670           {IndirectLocalPathEntry::DefaultInit, DIE, DIE->getField()});
6671       Init = DIE->getExpr();
6672     }
6673   } while (Init != Old);
6674
6675   if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Init)) {
6676     if (Visit(Path, Local(MTE), RK))
6677       visitLocalsRetainedByInitializer(Path, MTE->GetTemporaryExpr(), Visit,
6678                                        true);
6679   }
6680
6681   if (isa<CallExpr>(Init))
6682     return visitLifetimeBoundArguments(Path, Init, Visit);
6683
6684   switch (Init->getStmtClass()) {
6685   case Stmt::DeclRefExprClass: {
6686     // If we find the name of a local non-reference parameter, we could have a
6687     // lifetime problem.
6688     auto *DRE = cast<DeclRefExpr>(Init);
6689     auto *VD = dyn_cast<VarDecl>(DRE->getDecl());
6690     if (VD && VD->hasLocalStorage() &&
6691         !DRE->refersToEnclosingVariableOrCapture()) {
6692       if (!VD->getType()->isReferenceType()) {
6693         Visit(Path, Local(DRE), RK);
6694       } else if (isa<ParmVarDecl>(DRE->getDecl())) {
6695         // The lifetime of a reference parameter is unknown; assume it's OK
6696         // for now.
6697         break;
6698       } else if (VD->getInit() && !isVarOnPath(Path, VD)) {
6699         Path.push_back({IndirectLocalPathEntry::VarInit, DRE, VD});
6700         visitLocalsRetainedByReferenceBinding(Path, VD->getInit(),
6701                                               RK_ReferenceBinding, Visit);
6702       }
6703     }
6704     break;
6705   }
6706
6707   case Stmt::UnaryOperatorClass: {
6708     // The only unary operator that make sense to handle here
6709     // is Deref.  All others don't resolve to a "name."  This includes
6710     // handling all sorts of rvalues passed to a unary operator.
6711     const UnaryOperator *U = cast<UnaryOperator>(Init);
6712     if (U->getOpcode() == UO_Deref)
6713       visitLocalsRetainedByInitializer(Path, U->getSubExpr(), Visit, true);
6714     break;
6715   }
6716
6717   case Stmt::OMPArraySectionExprClass: {
6718     visitLocalsRetainedByInitializer(
6719         Path, cast<OMPArraySectionExpr>(Init)->getBase(), Visit, true);
6720     break;
6721   }
6722
6723   case Stmt::ConditionalOperatorClass:
6724   case Stmt::BinaryConditionalOperatorClass: {
6725     auto *C = cast<AbstractConditionalOperator>(Init);
6726     if (!C->getTrueExpr()->getType()->isVoidType())
6727       visitLocalsRetainedByReferenceBinding(Path, C->getTrueExpr(), RK, Visit);
6728     if (!C->getFalseExpr()->getType()->isVoidType())
6729       visitLocalsRetainedByReferenceBinding(Path, C->getFalseExpr(), RK, Visit);
6730     break;
6731   }
6732
6733   // FIXME: Visit the left-hand side of an -> or ->*.
6734
6735   default:
6736     break;
6737   }
6738 }
6739
6740 /// Visit the locals that would be reachable through an object initialized by
6741 /// the prvalue expression \c Init.
6742 static void visitLocalsRetainedByInitializer(IndirectLocalPath &Path,
6743                                              Expr *Init, LocalVisitor Visit,
6744                                              bool RevisitSubinits) {
6745   RevertToOldSizeRAII RAII(Path);
6746
6747   Expr *Old;
6748   do {
6749     Old = Init;
6750
6751     // Step into CXXDefaultInitExprs so we can diagnose cases where a
6752     // constructor inherits one as an implicit mem-initializer.
6753     if (auto *DIE = dyn_cast<CXXDefaultInitExpr>(Init)) {
6754       Path.push_back({IndirectLocalPathEntry::DefaultInit, DIE, DIE->getField()});
6755       Init = DIE->getExpr();
6756     }
6757
6758     if (auto *FE = dyn_cast<FullExpr>(Init))
6759       Init = FE->getSubExpr();
6760
6761     // Dig out the expression which constructs the extended temporary.
6762     Init = const_cast<Expr *>(Init->skipRValueSubobjectAdjustments());
6763
6764     if (CXXBindTemporaryExpr *BTE = dyn_cast<CXXBindTemporaryExpr>(Init))
6765       Init = BTE->getSubExpr();
6766
6767     Init = Init->IgnoreParens();
6768
6769     // Step over value-preserving rvalue casts.
6770     if (auto *CE = dyn_cast<CastExpr>(Init)) {
6771       switch (CE->getCastKind()) {
6772       case CK_LValueToRValue:
6773         // If we can match the lvalue to a const object, we can look at its
6774         // initializer.
6775         Path.push_back({IndirectLocalPathEntry::LValToRVal, CE});
6776         return visitLocalsRetainedByReferenceBinding(
6777             Path, Init, RK_ReferenceBinding,
6778             [&](IndirectLocalPath &Path, Local L, ReferenceKind RK) -> bool {
6779           if (auto *DRE = dyn_cast<DeclRefExpr>(L)) {
6780             auto *VD = dyn_cast<VarDecl>(DRE->getDecl());
6781             if (VD && VD->getType().isConstQualified() && VD->getInit() &&
6782                 !isVarOnPath(Path, VD)) {
6783               Path.push_back({IndirectLocalPathEntry::VarInit, DRE, VD});
6784               visitLocalsRetainedByInitializer(Path, VD->getInit(), Visit, true);
6785             }
6786           } else if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(L)) {
6787             if (MTE->getType().isConstQualified())
6788               visitLocalsRetainedByInitializer(Path, MTE->GetTemporaryExpr(),
6789                                                Visit, true);
6790           }
6791           return false;
6792         });
6793
6794         // We assume that objects can be retained by pointers cast to integers,
6795         // but not if the integer is cast to floating-point type or to _Complex.
6796         // We assume that casts to 'bool' do not preserve enough information to
6797         // retain a local object.
6798       case CK_NoOp:
6799       case CK_BitCast:
6800       case CK_BaseToDerived:
6801       case CK_DerivedToBase:
6802       case CK_UncheckedDerivedToBase:
6803       case CK_Dynamic:
6804       case CK_ToUnion:
6805       case CK_UserDefinedConversion:
6806       case CK_ConstructorConversion:
6807       case CK_IntegralToPointer:
6808       case CK_PointerToIntegral:
6809       case CK_VectorSplat:
6810       case CK_IntegralCast:
6811       case CK_CPointerToObjCPointerCast:
6812       case CK_BlockPointerToObjCPointerCast:
6813       case CK_AnyPointerToBlockPointerCast:
6814       case CK_AddressSpaceConversion:
6815         break;
6816
6817       case CK_ArrayToPointerDecay:
6818         // Model array-to-pointer decay as taking the address of the array
6819         // lvalue.
6820         Path.push_back({IndirectLocalPathEntry::AddressOf, CE});
6821         return visitLocalsRetainedByReferenceBinding(Path, CE->getSubExpr(),
6822                                                      RK_ReferenceBinding, Visit);
6823
6824       default:
6825         return;
6826       }
6827
6828       Init = CE->getSubExpr();
6829     }
6830   } while (Old != Init);
6831
6832   // C++17 [dcl.init.list]p6:
6833   //   initializing an initializer_list object from the array extends the
6834   //   lifetime of the array exactly like binding a reference to a temporary.
6835   if (auto *ILE = dyn_cast<CXXStdInitializerListExpr>(Init))
6836     return visitLocalsRetainedByReferenceBinding(Path, ILE->getSubExpr(),
6837                                                  RK_StdInitializerList, Visit);
6838
6839   if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
6840     // We already visited the elements of this initializer list while
6841     // performing the initialization. Don't visit them again unless we've
6842     // changed the lifetime of the initialized entity.
6843     if (!RevisitSubinits)
6844       return;
6845
6846     if (ILE->isTransparent())
6847       return visitLocalsRetainedByInitializer(Path, ILE->getInit(0), Visit,
6848                                               RevisitSubinits);
6849
6850     if (ILE->getType()->isArrayType()) {
6851       for (unsigned I = 0, N = ILE->getNumInits(); I != N; ++I)
6852         visitLocalsRetainedByInitializer(Path, ILE->getInit(I), Visit,
6853                                          RevisitSubinits);
6854       return;
6855     }
6856
6857     if (CXXRecordDecl *RD = ILE->getType()->getAsCXXRecordDecl()) {
6858       assert(RD->isAggregate() && "aggregate init on non-aggregate");
6859
6860       // If we lifetime-extend a braced initializer which is initializing an
6861       // aggregate, and that aggregate contains reference members which are
6862       // bound to temporaries, those temporaries are also lifetime-extended.
6863       if (RD->isUnion() && ILE->getInitializedFieldInUnion() &&
6864           ILE->getInitializedFieldInUnion()->getType()->isReferenceType())
6865         visitLocalsRetainedByReferenceBinding(Path, ILE->getInit(0),
6866                                               RK_ReferenceBinding, Visit);
6867       else {
6868         unsigned Index = 0;
6869         for (; Index < RD->getNumBases() && Index < ILE->getNumInits(); ++Index)
6870           visitLocalsRetainedByInitializer(Path, ILE->getInit(Index), Visit,
6871                                            RevisitSubinits);
6872         for (const auto *I : RD->fields()) {
6873           if (Index >= ILE->getNumInits())
6874             break;
6875           if (I->isUnnamedBitfield())
6876             continue;
6877           Expr *SubInit = ILE->getInit(Index);
6878           if (I->getType()->isReferenceType())
6879             visitLocalsRetainedByReferenceBinding(Path, SubInit,
6880                                                   RK_ReferenceBinding, Visit);
6881           else
6882             // This might be either aggregate-initialization of a member or
6883             // initialization of a std::initializer_list object. Regardless,
6884             // we should recursively lifetime-extend that initializer.
6885             visitLocalsRetainedByInitializer(Path, SubInit, Visit,
6886                                              RevisitSubinits);
6887           ++Index;
6888         }
6889       }
6890     }
6891     return;
6892   }
6893
6894   // The lifetime of an init-capture is that of the closure object constructed
6895   // by a lambda-expression.
6896   if (auto *LE = dyn_cast<LambdaExpr>(Init)) {
6897     for (Expr *E : LE->capture_inits()) {
6898       if (!E)
6899         continue;
6900       if (E->isGLValue())
6901         visitLocalsRetainedByReferenceBinding(Path, E, RK_ReferenceBinding,
6902                                               Visit);
6903       else
6904         visitLocalsRetainedByInitializer(Path, E, Visit, true);
6905     }
6906   }
6907
6908   if (isa<CallExpr>(Init) || isa<CXXConstructExpr>(Init))
6909     return visitLifetimeBoundArguments(Path, Init, Visit);
6910
6911   switch (Init->getStmtClass()) {
6912   case Stmt::UnaryOperatorClass: {
6913     auto *UO = cast<UnaryOperator>(Init);
6914     // If the initializer is the address of a local, we could have a lifetime
6915     // problem.
6916     if (UO->getOpcode() == UO_AddrOf) {
6917       // If this is &rvalue, then it's ill-formed and we have already diagnosed
6918       // it. Don't produce a redundant warning about the lifetime of the
6919       // temporary.
6920       if (isa<MaterializeTemporaryExpr>(UO->getSubExpr()))
6921         return;
6922
6923       Path.push_back({IndirectLocalPathEntry::AddressOf, UO});
6924       visitLocalsRetainedByReferenceBinding(Path, UO->getSubExpr(),
6925                                             RK_ReferenceBinding, Visit);
6926     }
6927     break;
6928   }
6929
6930   case Stmt::BinaryOperatorClass: {
6931     // Handle pointer arithmetic.
6932     auto *BO = cast<BinaryOperator>(Init);
6933     BinaryOperatorKind BOK = BO->getOpcode();
6934     if (!BO->getType()->isPointerType() || (BOK != BO_Add && BOK != BO_Sub))
6935       break;
6936
6937     if (BO->getLHS()->getType()->isPointerType())
6938       visitLocalsRetainedByInitializer(Path, BO->getLHS(), Visit, true);
6939     else if (BO->getRHS()->getType()->isPointerType())
6940       visitLocalsRetainedByInitializer(Path, BO->getRHS(), Visit, true);
6941     break;
6942   }
6943
6944   case Stmt::ConditionalOperatorClass:
6945   case Stmt::BinaryConditionalOperatorClass: {
6946     auto *C = cast<AbstractConditionalOperator>(Init);
6947     // In C++, we can have a throw-expression operand, which has 'void' type
6948     // and isn't interesting from a lifetime perspective.
6949     if (!C->getTrueExpr()->getType()->isVoidType())
6950       visitLocalsRetainedByInitializer(Path, C->getTrueExpr(), Visit, true);
6951     if (!C->getFalseExpr()->getType()->isVoidType())
6952       visitLocalsRetainedByInitializer(Path, C->getFalseExpr(), Visit, true);
6953     break;
6954   }
6955
6956   case Stmt::BlockExprClass:
6957     if (cast<BlockExpr>(Init)->getBlockDecl()->hasCaptures()) {
6958       // This is a local block, whose lifetime is that of the function.
6959       Visit(Path, Local(cast<BlockExpr>(Init)), RK_ReferenceBinding);
6960     }
6961     break;
6962
6963   case Stmt::AddrLabelExprClass:
6964     // We want to warn if the address of a label would escape the function.
6965     Visit(Path, Local(cast<AddrLabelExpr>(Init)), RK_ReferenceBinding);
6966     break;
6967
6968   default:
6969     break;
6970   }
6971 }
6972
6973 /// Determine whether this is an indirect path to a temporary that we are
6974 /// supposed to lifetime-extend along (but don't).
6975 static bool shouldLifetimeExtendThroughPath(const IndirectLocalPath &Path) {
6976   for (auto Elem : Path) {
6977     if (Elem.Kind != IndirectLocalPathEntry::DefaultInit)
6978       return false;
6979   }
6980   return true;
6981 }
6982
6983 /// Find the range for the first interesting entry in the path at or after I.
6984 static SourceRange nextPathEntryRange(const IndirectLocalPath &Path, unsigned I,
6985                                       Expr *E) {
6986   for (unsigned N = Path.size(); I != N; ++I) {
6987     switch (Path[I].Kind) {
6988     case IndirectLocalPathEntry::AddressOf:
6989     case IndirectLocalPathEntry::LValToRVal:
6990     case IndirectLocalPathEntry::LifetimeBoundCall:
6991       // These exist primarily to mark the path as not permitting or
6992       // supporting lifetime extension.
6993       break;
6994
6995     case IndirectLocalPathEntry::DefaultInit:
6996     case IndirectLocalPathEntry::VarInit:
6997       return Path[I].E->getSourceRange();
6998     }
6999   }
7000   return E->getSourceRange();
7001 }
7002
7003 void Sema::checkInitializerLifetime(const InitializedEntity &Entity,
7004                                     Expr *Init) {
7005   LifetimeResult LR = getEntityLifetime(&Entity);
7006   LifetimeKind LK = LR.getInt();
7007   const InitializedEntity *ExtendingEntity = LR.getPointer();
7008
7009   // If this entity doesn't have an interesting lifetime, don't bother looking
7010   // for temporaries within its initializer.
7011   if (LK == LK_FullExpression)
7012     return;
7013
7014   auto TemporaryVisitor = [&](IndirectLocalPath &Path, Local L,
7015                               ReferenceKind RK) -> bool {
7016     SourceRange DiagRange = nextPathEntryRange(Path, 0, L);
7017     SourceLocation DiagLoc = DiagRange.getBegin();
7018
7019     switch (LK) {
7020     case LK_FullExpression:
7021       llvm_unreachable("already handled this");
7022
7023     case LK_Extended: {
7024       auto *MTE = dyn_cast<MaterializeTemporaryExpr>(L);
7025       if (!MTE) {
7026         // The initialized entity has lifetime beyond the full-expression,
7027         // and the local entity does too, so don't warn.
7028         //
7029         // FIXME: We should consider warning if a static / thread storage
7030         // duration variable retains an automatic storage duration local.
7031         return false;
7032       }
7033
7034       // Lifetime-extend the temporary.
7035       if (Path.empty()) {
7036         // Update the storage duration of the materialized temporary.
7037         // FIXME: Rebuild the expression instead of mutating it.
7038         MTE->setExtendingDecl(ExtendingEntity->getDecl(),
7039                               ExtendingEntity->allocateManglingNumber());
7040         // Also visit the temporaries lifetime-extended by this initializer.
7041         return true;
7042       }
7043
7044       if (shouldLifetimeExtendThroughPath(Path)) {
7045         // We're supposed to lifetime-extend the temporary along this path (per
7046         // the resolution of DR1815), but we don't support that yet.
7047         //
7048         // FIXME: Properly handle this situation. Perhaps the easiest approach
7049         // would be to clone the initializer expression on each use that would
7050         // lifetime extend its temporaries.
7051         Diag(DiagLoc, diag::warn_unsupported_lifetime_extension)
7052             << RK << DiagRange;
7053       } else {
7054         // If the path goes through the initialization of a variable or field,
7055         // it can't possibly reach a temporary created in this full-expression.
7056         // We will have already diagnosed any problems with the initializer.
7057         if (pathContainsInit(Path))
7058           return false;
7059
7060         Diag(DiagLoc, diag::warn_dangling_variable)
7061             << RK << !Entity.getParent()
7062             << ExtendingEntity->getDecl()->isImplicit()
7063             << ExtendingEntity->getDecl() << Init->isGLValue() << DiagRange;
7064       }
7065       break;
7066     }
7067
7068     case LK_MemInitializer: {
7069       if (isa<MaterializeTemporaryExpr>(L)) {
7070         // Under C++ DR1696, if a mem-initializer (or a default member
7071         // initializer used by the absence of one) would lifetime-extend a
7072         // temporary, the program is ill-formed.
7073         if (auto *ExtendingDecl =
7074                 ExtendingEntity ? ExtendingEntity->getDecl() : nullptr) {
7075           bool IsSubobjectMember = ExtendingEntity != &Entity;
7076           Diag(DiagLoc, shouldLifetimeExtendThroughPath(Path)
7077                             ? diag::err_dangling_member
7078                             : diag::warn_dangling_member)
7079               << ExtendingDecl << IsSubobjectMember << RK << DiagRange;
7080           // Don't bother adding a note pointing to the field if we're inside
7081           // its default member initializer; our primary diagnostic points to
7082           // the same place in that case.
7083           if (Path.empty() ||
7084               Path.back().Kind != IndirectLocalPathEntry::DefaultInit) {
7085             Diag(ExtendingDecl->getLocation(),
7086                  diag::note_lifetime_extending_member_declared_here)
7087                 << RK << IsSubobjectMember;
7088           }
7089         } else {
7090           // We have a mem-initializer but no particular field within it; this
7091           // is either a base class or a delegating initializer directly
7092           // initializing the base-class from something that doesn't live long
7093           // enough.
7094           //
7095           // FIXME: Warn on this.
7096           return false;
7097         }
7098       } else {
7099         // Paths via a default initializer can only occur during error recovery
7100         // (there's no other way that a default initializer can refer to a
7101         // local). Don't produce a bogus warning on those cases.
7102         if (pathContainsInit(Path))
7103           return false;
7104
7105         auto *DRE = dyn_cast<DeclRefExpr>(L);
7106         auto *VD = DRE ? dyn_cast<VarDecl>(DRE->getDecl()) : nullptr;
7107         if (!VD) {
7108           // A member was initialized to a local block.
7109           // FIXME: Warn on this.
7110           return false;
7111         }
7112
7113         if (auto *Member =
7114                 ExtendingEntity ? ExtendingEntity->getDecl() : nullptr) {
7115           bool IsPointer = Member->getType()->isAnyPointerType();
7116           Diag(DiagLoc, IsPointer ? diag::warn_init_ptr_member_to_parameter_addr
7117                                   : diag::warn_bind_ref_member_to_parameter)
7118               << Member << VD << isa<ParmVarDecl>(VD) << DiagRange;
7119           Diag(Member->getLocation(),
7120                diag::note_ref_or_ptr_member_declared_here)
7121               << (unsigned)IsPointer;
7122         }
7123       }
7124       break;
7125     }
7126
7127     case LK_New:
7128       if (isa<MaterializeTemporaryExpr>(L)) {
7129         Diag(DiagLoc, RK == RK_ReferenceBinding
7130                           ? diag::warn_new_dangling_reference
7131                           : diag::warn_new_dangling_initializer_list)
7132             << !Entity.getParent() << DiagRange;
7133       } else {
7134         // We can't determine if the allocation outlives the local declaration.
7135         return false;
7136       }
7137       break;
7138
7139     case LK_Return:
7140     case LK_StmtExprResult:
7141       if (auto *DRE = dyn_cast<DeclRefExpr>(L)) {
7142         // We can't determine if the local variable outlives the statement
7143         // expression.
7144         if (LK == LK_StmtExprResult)
7145           return false;
7146         Diag(DiagLoc, diag::warn_ret_stack_addr_ref)
7147             << Entity.getType()->isReferenceType() << DRE->getDecl()
7148             << isa<ParmVarDecl>(DRE->getDecl()) << DiagRange;
7149       } else if (isa<BlockExpr>(L)) {
7150         Diag(DiagLoc, diag::err_ret_local_block) << DiagRange;
7151       } else if (isa<AddrLabelExpr>(L)) {
7152         // Don't warn when returning a label from a statement expression.
7153         // Leaving the scope doesn't end its lifetime.
7154         if (LK == LK_StmtExprResult)
7155           return false;
7156         Diag(DiagLoc, diag::warn_ret_addr_label) << DiagRange;
7157       } else {
7158         Diag(DiagLoc, diag::warn_ret_local_temp_addr_ref)
7159          << Entity.getType()->isReferenceType() << DiagRange;
7160       }
7161       break;
7162     }
7163
7164     for (unsigned I = 0; I != Path.size(); ++I) {
7165       auto Elem = Path[I];
7166
7167       switch (Elem.Kind) {
7168       case IndirectLocalPathEntry::AddressOf:
7169       case IndirectLocalPathEntry::LValToRVal:
7170         // These exist primarily to mark the path as not permitting or
7171         // supporting lifetime extension.
7172         break;
7173
7174       case IndirectLocalPathEntry::LifetimeBoundCall:
7175         // FIXME: Consider adding a note for this.
7176         break;
7177
7178       case IndirectLocalPathEntry::DefaultInit: {
7179         auto *FD = cast<FieldDecl>(Elem.D);
7180         Diag(FD->getLocation(), diag::note_init_with_default_member_initalizer)
7181             << FD << nextPathEntryRange(Path, I + 1, L);
7182         break;
7183       }
7184
7185       case IndirectLocalPathEntry::VarInit:
7186         const VarDecl *VD = cast<VarDecl>(Elem.D);
7187         Diag(VD->getLocation(), diag::note_local_var_initializer)
7188             << VD->getType()->isReferenceType()
7189             << VD->isImplicit() << VD->getDeclName()
7190             << nextPathEntryRange(Path, I + 1, L);
7191         break;
7192       }
7193     }
7194
7195     // We didn't lifetime-extend, so don't go any further; we don't need more
7196     // warnings or errors on inner temporaries within this one's initializer.
7197     return false;
7198   };
7199
7200   llvm::SmallVector<IndirectLocalPathEntry, 8> Path;
7201   if (Init->isGLValue())
7202     visitLocalsRetainedByReferenceBinding(Path, Init, RK_ReferenceBinding,
7203                                           TemporaryVisitor);
7204   else
7205     visitLocalsRetainedByInitializer(Path, Init, TemporaryVisitor, false);
7206 }
7207
7208 static void DiagnoseNarrowingInInitList(Sema &S,
7209                                         const ImplicitConversionSequence &ICS,
7210                                         QualType PreNarrowingType,
7211                                         QualType EntityType,
7212                                         const Expr *PostInit);
7213
7214 /// Provide warnings when std::move is used on construction.
7215 static void CheckMoveOnConstruction(Sema &S, const Expr *InitExpr,
7216                                     bool IsReturnStmt) {
7217   if (!InitExpr)
7218     return;
7219
7220   if (S.inTemplateInstantiation())
7221     return;
7222
7223   QualType DestType = InitExpr->getType();
7224   if (!DestType->isRecordType())
7225     return;
7226
7227   unsigned DiagID = 0;
7228   if (IsReturnStmt) {
7229     const CXXConstructExpr *CCE =
7230         dyn_cast<CXXConstructExpr>(InitExpr->IgnoreParens());
7231     if (!CCE || CCE->getNumArgs() != 1)
7232       return;
7233
7234     if (!CCE->getConstructor()->isCopyOrMoveConstructor())
7235       return;
7236
7237     InitExpr = CCE->getArg(0)->IgnoreImpCasts();
7238   }
7239
7240   // Find the std::move call and get the argument.
7241   const CallExpr *CE = dyn_cast<CallExpr>(InitExpr->IgnoreParens());
7242   if (!CE || !CE->isCallToStdMove())
7243     return;
7244
7245   const Expr *Arg = CE->getArg(0)->IgnoreImplicit();
7246
7247   if (IsReturnStmt) {
7248     const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg->IgnoreParenImpCasts());
7249     if (!DRE || DRE->refersToEnclosingVariableOrCapture())
7250       return;
7251
7252     const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl());
7253     if (!VD || !VD->hasLocalStorage())
7254       return;
7255
7256     // __block variables are not moved implicitly.
7257     if (VD->hasAttr<BlocksAttr>())
7258       return;
7259
7260     QualType SourceType = VD->getType();
7261     if (!SourceType->isRecordType())
7262       return;
7263
7264     if (!S.Context.hasSameUnqualifiedType(DestType, SourceType)) {
7265       return;
7266     }
7267
7268     // If we're returning a function parameter, copy elision
7269     // is not possible.
7270     if (isa<ParmVarDecl>(VD))
7271       DiagID = diag::warn_redundant_move_on_return;
7272     else
7273       DiagID = diag::warn_pessimizing_move_on_return;
7274   } else {
7275     DiagID = diag::warn_pessimizing_move_on_initialization;
7276     const Expr *ArgStripped = Arg->IgnoreImplicit()->IgnoreParens();
7277     if (!ArgStripped->isRValue() || !ArgStripped->getType()->isRecordType())
7278       return;
7279   }
7280
7281   S.Diag(CE->getBeginLoc(), DiagID);
7282
7283   // Get all the locations for a fix-it.  Don't emit the fix-it if any location
7284   // is within a macro.
7285   SourceLocation CallBegin = CE->getCallee()->getBeginLoc();
7286   if (CallBegin.isMacroID())
7287     return;
7288   SourceLocation RParen = CE->getRParenLoc();
7289   if (RParen.isMacroID())
7290     return;
7291   SourceLocation LParen;
7292   SourceLocation ArgLoc = Arg->getBeginLoc();
7293
7294   // Special testing for the argument location.  Since the fix-it needs the
7295   // location right before the argument, the argument location can be in a
7296   // macro only if it is at the beginning of the macro.
7297   while (ArgLoc.isMacroID() &&
7298          S.getSourceManager().isAtStartOfImmediateMacroExpansion(ArgLoc)) {
7299     ArgLoc = S.getSourceManager().getImmediateExpansionRange(ArgLoc).getBegin();
7300   }
7301
7302   if (LParen.isMacroID())
7303     return;
7304
7305   LParen = ArgLoc.getLocWithOffset(-1);
7306
7307   S.Diag(CE->getBeginLoc(), diag::note_remove_move)
7308       << FixItHint::CreateRemoval(SourceRange(CallBegin, LParen))
7309       << FixItHint::CreateRemoval(SourceRange(RParen, RParen));
7310 }
7311
7312 static void CheckForNullPointerDereference(Sema &S, const Expr *E) {
7313   // Check to see if we are dereferencing a null pointer.  If so, this is
7314   // undefined behavior, so warn about it.  This only handles the pattern
7315   // "*null", which is a very syntactic check.
7316   if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E->IgnoreParenCasts()))
7317     if (UO->getOpcode() == UO_Deref &&
7318         UO->getSubExpr()->IgnoreParenCasts()->
7319         isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)) {
7320     S.DiagRuntimeBehavior(UO->getOperatorLoc(), UO,
7321                           S.PDiag(diag::warn_binding_null_to_reference)
7322                             << UO->getSubExpr()->getSourceRange());
7323   }
7324 }
7325
7326 MaterializeTemporaryExpr *
7327 Sema::CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
7328                                      bool BoundToLvalueReference) {
7329   auto MTE = new (Context)
7330       MaterializeTemporaryExpr(T, Temporary, BoundToLvalueReference);
7331
7332   // Order an ExprWithCleanups for lifetime marks.
7333   //
7334   // TODO: It'll be good to have a single place to check the access of the
7335   // destructor and generate ExprWithCleanups for various uses. Currently these
7336   // are done in both CreateMaterializeTemporaryExpr and MaybeBindToTemporary,
7337   // but there may be a chance to merge them.
7338   Cleanup.setExprNeedsCleanups(false);
7339   return MTE;
7340 }
7341
7342 ExprResult Sema::TemporaryMaterializationConversion(Expr *E) {
7343   // In C++98, we don't want to implicitly create an xvalue.
7344   // FIXME: This means that AST consumers need to deal with "prvalues" that
7345   // denote materialized temporaries. Maybe we should add another ValueKind
7346   // for "xvalue pretending to be a prvalue" for C++98 support.
7347   if (!E->isRValue() || !getLangOpts().CPlusPlus11)
7348     return E;
7349
7350   // C++1z [conv.rval]/1: T shall be a complete type.
7351   // FIXME: Does this ever matter (can we form a prvalue of incomplete type)?
7352   // If so, we should check for a non-abstract class type here too.
7353   QualType T = E->getType();
7354   if (RequireCompleteType(E->getExprLoc(), T, diag::err_incomplete_type))
7355     return ExprError();
7356
7357   return CreateMaterializeTemporaryExpr(E->getType(), E, false);
7358 }
7359
7360 ExprResult Sema::PerformQualificationConversion(Expr *E, QualType Ty,
7361                                                 ExprValueKind VK,
7362                                                 CheckedConversionKind CCK) {
7363
7364   CastKind CK = CK_NoOp;
7365
7366   if (VK == VK_RValue) {
7367     auto PointeeTy = Ty->getPointeeType();
7368     auto ExprPointeeTy = E->getType()->getPointeeType();
7369     if (!PointeeTy.isNull() &&
7370         PointeeTy.getAddressSpace() != ExprPointeeTy.getAddressSpace())
7371       CK = CK_AddressSpaceConversion;
7372   } else if (Ty.getAddressSpace() != E->getType().getAddressSpace()) {
7373     CK = CK_AddressSpaceConversion;
7374   }
7375
7376   return ImpCastExprToType(E, Ty, CK, VK, /*BasePath=*/nullptr, CCK);
7377 }
7378
7379 ExprResult InitializationSequence::Perform(Sema &S,
7380                                            const InitializedEntity &Entity,
7381                                            const InitializationKind &Kind,
7382                                            MultiExprArg Args,
7383                                            QualType *ResultType) {
7384   if (Failed()) {
7385     Diagnose(S, Entity, Kind, Args);
7386     return ExprError();
7387   }
7388   if (!ZeroInitializationFixit.empty()) {
7389     unsigned DiagID = diag::err_default_init_const;
7390     if (Decl *D = Entity.getDecl())
7391       if (S.getLangOpts().MSVCCompat && D->hasAttr<SelectAnyAttr>())
7392         DiagID = diag::ext_default_init_const;
7393
7394     // The initialization would have succeeded with this fixit. Since the fixit
7395     // is on the error, we need to build a valid AST in this case, so this isn't
7396     // handled in the Failed() branch above.
7397     QualType DestType = Entity.getType();
7398     S.Diag(Kind.getLocation(), DiagID)
7399         << DestType << (bool)DestType->getAs<RecordType>()
7400         << FixItHint::CreateInsertion(ZeroInitializationFixitLoc,
7401                                       ZeroInitializationFixit);
7402   }
7403
7404   if (getKind() == DependentSequence) {
7405     // If the declaration is a non-dependent, incomplete array type
7406     // that has an initializer, then its type will be completed once
7407     // the initializer is instantiated.
7408     if (ResultType && !Entity.getType()->isDependentType() &&
7409         Args.size() == 1) {
7410       QualType DeclType = Entity.getType();
7411       if (const IncompleteArrayType *ArrayT
7412                            = S.Context.getAsIncompleteArrayType(DeclType)) {
7413         // FIXME: We don't currently have the ability to accurately
7414         // compute the length of an initializer list without
7415         // performing full type-checking of the initializer list
7416         // (since we have to determine where braces are implicitly
7417         // introduced and such).  So, we fall back to making the array
7418         // type a dependently-sized array type with no specified
7419         // bound.
7420         if (isa<InitListExpr>((Expr *)Args[0])) {
7421           SourceRange Brackets;
7422
7423           // Scavange the location of the brackets from the entity, if we can.
7424           if (auto *DD = dyn_cast_or_null<DeclaratorDecl>(Entity.getDecl())) {
7425             if (TypeSourceInfo *TInfo = DD->getTypeSourceInfo()) {
7426               TypeLoc TL = TInfo->getTypeLoc();
7427               if (IncompleteArrayTypeLoc ArrayLoc =
7428                       TL.getAs<IncompleteArrayTypeLoc>())
7429                 Brackets = ArrayLoc.getBracketsRange();
7430             }
7431           }
7432
7433           *ResultType
7434             = S.Context.getDependentSizedArrayType(ArrayT->getElementType(),
7435                                                    /*NumElts=*/nullptr,
7436                                                    ArrayT->getSizeModifier(),
7437                                        ArrayT->getIndexTypeCVRQualifiers(),
7438                                                    Brackets);
7439         }
7440
7441       }
7442     }
7443     if (Kind.getKind() == InitializationKind::IK_Direct &&
7444         !Kind.isExplicitCast()) {
7445       // Rebuild the ParenListExpr.
7446       SourceRange ParenRange = Kind.getParenOrBraceRange();
7447       return S.ActOnParenListExpr(ParenRange.getBegin(), ParenRange.getEnd(),
7448                                   Args);
7449     }
7450     assert(Kind.getKind() == InitializationKind::IK_Copy ||
7451            Kind.isExplicitCast() ||
7452            Kind.getKind() == InitializationKind::IK_DirectList);
7453     return ExprResult(Args[0]);
7454   }
7455
7456   // No steps means no initialization.
7457   if (Steps.empty())
7458     return ExprResult((Expr *)nullptr);
7459
7460   if (S.getLangOpts().CPlusPlus11 && Entity.getType()->isReferenceType() &&
7461       Args.size() == 1 && isa<InitListExpr>(Args[0]) &&
7462       !Entity.isParameterKind()) {
7463     // Produce a C++98 compatibility warning if we are initializing a reference
7464     // from an initializer list. For parameters, we produce a better warning
7465     // elsewhere.
7466     Expr *Init = Args[0];
7467     S.Diag(Init->getBeginLoc(), diag::warn_cxx98_compat_reference_list_init)
7468         << Init->getSourceRange();
7469   }
7470
7471   // OpenCL v2.0 s6.13.11.1. atomic variables can be initialized in global scope
7472   QualType ETy = Entity.getType();
7473   Qualifiers TyQualifiers = ETy.getQualifiers();
7474   bool HasGlobalAS = TyQualifiers.hasAddressSpace() &&
7475                      TyQualifiers.getAddressSpace() == LangAS::opencl_global;
7476
7477   if (S.getLangOpts().OpenCLVersion >= 200 &&
7478       ETy->isAtomicType() && !HasGlobalAS &&
7479       Entity.getKind() == InitializedEntity::EK_Variable && Args.size() > 0) {
7480     S.Diag(Args[0]->getBeginLoc(), diag::err_opencl_atomic_init)
7481         << 1
7482         << SourceRange(Entity.getDecl()->getBeginLoc(), Args[0]->getEndLoc());
7483     return ExprError();
7484   }
7485
7486   QualType DestType = Entity.getType().getNonReferenceType();
7487   // FIXME: Ugly hack around the fact that Entity.getType() is not
7488   // the same as Entity.getDecl()->getType() in cases involving type merging,
7489   //  and we want latter when it makes sense.
7490   if (ResultType)
7491     *ResultType = Entity.getDecl() ? Entity.getDecl()->getType() :
7492                                      Entity.getType();
7493
7494   ExprResult CurInit((Expr *)nullptr);
7495   SmallVector<Expr*, 4> ArrayLoopCommonExprs;
7496
7497   // For initialization steps that start with a single initializer,
7498   // grab the only argument out the Args and place it into the "current"
7499   // initializer.
7500   switch (Steps.front().Kind) {
7501   case SK_ResolveAddressOfOverloadedFunction:
7502   case SK_CastDerivedToBaseRValue:
7503   case SK_CastDerivedToBaseXValue:
7504   case SK_CastDerivedToBaseLValue:
7505   case SK_BindReference:
7506   case SK_BindReferenceToTemporary:
7507   case SK_FinalCopy:
7508   case SK_ExtraneousCopyToTemporary:
7509   case SK_UserConversion:
7510   case SK_QualificationConversionLValue:
7511   case SK_QualificationConversionXValue:
7512   case SK_QualificationConversionRValue:
7513   case SK_AtomicConversion:
7514   case SK_ConversionSequence:
7515   case SK_ConversionSequenceNoNarrowing:
7516   case SK_ListInitialization:
7517   case SK_UnwrapInitList:
7518   case SK_RewrapInitList:
7519   case SK_CAssignment:
7520   case SK_StringInit:
7521   case SK_ObjCObjectConversion:
7522   case SK_ArrayLoopIndex:
7523   case SK_ArrayLoopInit:
7524   case SK_ArrayInit:
7525   case SK_GNUArrayInit:
7526   case SK_ParenthesizedArrayInit:
7527   case SK_PassByIndirectCopyRestore:
7528   case SK_PassByIndirectRestore:
7529   case SK_ProduceObjCObject:
7530   case SK_StdInitializerList:
7531   case SK_OCLSamplerInit:
7532   case SK_OCLZeroOpaqueType: {
7533     assert(Args.size() == 1);
7534     CurInit = Args[0];
7535     if (!CurInit.get()) return ExprError();
7536     break;
7537   }
7538
7539   case SK_ConstructorInitialization:
7540   case SK_ConstructorInitializationFromList:
7541   case SK_StdInitializerListConstructorCall:
7542   case SK_ZeroInitialization:
7543     break;
7544   }
7545
7546   // Promote from an unevaluated context to an unevaluated list context in
7547   // C++11 list-initialization; we need to instantiate entities usable in
7548   // constant expressions here in order to perform narrowing checks =(
7549   EnterExpressionEvaluationContext Evaluated(
7550       S, EnterExpressionEvaluationContext::InitList,
7551       CurInit.get() && isa<InitListExpr>(CurInit.get()));
7552
7553   // C++ [class.abstract]p2:
7554   //   no objects of an abstract class can be created except as subobjects
7555   //   of a class derived from it
7556   auto checkAbstractType = [&](QualType T) -> bool {
7557     if (Entity.getKind() == InitializedEntity::EK_Base ||
7558         Entity.getKind() == InitializedEntity::EK_Delegating)
7559       return false;
7560     return S.RequireNonAbstractType(Kind.getLocation(), T,
7561                                     diag::err_allocation_of_abstract_type);
7562   };
7563
7564   // Walk through the computed steps for the initialization sequence,
7565   // performing the specified conversions along the way.
7566   bool ConstructorInitRequiresZeroInit = false;
7567   for (step_iterator Step = step_begin(), StepEnd = step_end();
7568        Step != StepEnd; ++Step) {
7569     if (CurInit.isInvalid())
7570       return ExprError();
7571
7572     QualType SourceType = CurInit.get() ? CurInit.get()->getType() : QualType();
7573
7574     switch (Step->Kind) {
7575     case SK_ResolveAddressOfOverloadedFunction:
7576       // Overload resolution determined which function invoke; update the
7577       // initializer to reflect that choice.
7578       S.CheckAddressOfMemberAccess(CurInit.get(), Step->Function.FoundDecl);
7579       if (S.DiagnoseUseOfDecl(Step->Function.FoundDecl, Kind.getLocation()))
7580         return ExprError();
7581       CurInit = S.FixOverloadedFunctionReference(CurInit,
7582                                                  Step->Function.FoundDecl,
7583                                                  Step->Function.Function);
7584       break;
7585
7586     case SK_CastDerivedToBaseRValue:
7587     case SK_CastDerivedToBaseXValue:
7588     case SK_CastDerivedToBaseLValue: {
7589       // We have a derived-to-base cast that produces either an rvalue or an
7590       // lvalue. Perform that cast.
7591
7592       CXXCastPath BasePath;
7593
7594       // Casts to inaccessible base classes are allowed with C-style casts.
7595       bool IgnoreBaseAccess = Kind.isCStyleOrFunctionalCast();
7596       if (S.CheckDerivedToBaseConversion(
7597               SourceType, Step->Type, CurInit.get()->getBeginLoc(),
7598               CurInit.get()->getSourceRange(), &BasePath, IgnoreBaseAccess))
7599         return ExprError();
7600
7601       ExprValueKind VK =
7602           Step->Kind == SK_CastDerivedToBaseLValue ?
7603               VK_LValue :
7604               (Step->Kind == SK_CastDerivedToBaseXValue ?
7605                    VK_XValue :
7606                    VK_RValue);
7607       CurInit =
7608           ImplicitCastExpr::Create(S.Context, Step->Type, CK_DerivedToBase,
7609                                    CurInit.get(), &BasePath, VK);
7610       break;
7611     }
7612
7613     case SK_BindReference:
7614       // Reference binding does not have any corresponding ASTs.
7615
7616       // Check exception specifications
7617       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
7618         return ExprError();
7619
7620       // We don't check for e.g. function pointers here, since address
7621       // availability checks should only occur when the function first decays
7622       // into a pointer or reference.
7623       if (CurInit.get()->getType()->isFunctionProtoType()) {
7624         if (auto *DRE = dyn_cast<DeclRefExpr>(CurInit.get()->IgnoreParens())) {
7625           if (auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
7626             if (!S.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
7627                                                      DRE->getBeginLoc()))
7628               return ExprError();
7629           }
7630         }
7631       }
7632
7633       CheckForNullPointerDereference(S, CurInit.get());
7634       break;
7635
7636     case SK_BindReferenceToTemporary: {
7637       // Make sure the "temporary" is actually an rvalue.
7638       assert(CurInit.get()->isRValue() && "not a temporary");
7639
7640       // Check exception specifications
7641       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
7642         return ExprError();
7643
7644       // Materialize the temporary into memory.
7645       MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
7646           Step->Type, CurInit.get(), Entity.getType()->isLValueReferenceType());
7647       CurInit = MTE;
7648
7649       // If we're extending this temporary to automatic storage duration -- we
7650       // need to register its cleanup during the full-expression's cleanups.
7651       if (MTE->getStorageDuration() == SD_Automatic &&
7652           MTE->getType().isDestructedType())
7653         S.Cleanup.setExprNeedsCleanups(true);
7654       break;
7655     }
7656
7657     case SK_FinalCopy:
7658       if (checkAbstractType(Step->Type))
7659         return ExprError();
7660
7661       // If the overall initialization is initializing a temporary, we already
7662       // bound our argument if it was necessary to do so. If not (if we're
7663       // ultimately initializing a non-temporary), our argument needs to be
7664       // bound since it's initializing a function parameter.
7665       // FIXME: This is a mess. Rationalize temporary destruction.
7666       if (!shouldBindAsTemporary(Entity))
7667         CurInit = S.MaybeBindToTemporary(CurInit.get());
7668       CurInit = CopyObject(S, Step->Type, Entity, CurInit,
7669                            /*IsExtraneousCopy=*/false);
7670       break;
7671
7672     case SK_ExtraneousCopyToTemporary:
7673       CurInit = CopyObject(S, Step->Type, Entity, CurInit,
7674                            /*IsExtraneousCopy=*/true);
7675       break;
7676
7677     case SK_UserConversion: {
7678       // We have a user-defined conversion that invokes either a constructor
7679       // or a conversion function.
7680       CastKind CastKind;
7681       FunctionDecl *Fn = Step->Function.Function;
7682       DeclAccessPair FoundFn = Step->Function.FoundDecl;
7683       bool HadMultipleCandidates = Step->Function.HadMultipleCandidates;
7684       bool CreatedObject = false;
7685       if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(Fn)) {
7686         // Build a call to the selected constructor.
7687         SmallVector<Expr*, 8> ConstructorArgs;
7688         SourceLocation Loc = CurInit.get()->getBeginLoc();
7689
7690         // Determine the arguments required to actually perform the constructor
7691         // call.
7692         Expr *Arg = CurInit.get();
7693         if (S.CompleteConstructorCall(Constructor,
7694                                       MultiExprArg(&Arg, 1),
7695                                       Loc, ConstructorArgs))
7696           return ExprError();
7697
7698         // Build an expression that constructs a temporary.
7699         CurInit = S.BuildCXXConstructExpr(Loc, Step->Type,
7700                                           FoundFn, Constructor,
7701                                           ConstructorArgs,
7702                                           HadMultipleCandidates,
7703                                           /*ListInit*/ false,
7704                                           /*StdInitListInit*/ false,
7705                                           /*ZeroInit*/ false,
7706                                           CXXConstructExpr::CK_Complete,
7707                                           SourceRange());
7708         if (CurInit.isInvalid())
7709           return ExprError();
7710
7711         S.CheckConstructorAccess(Kind.getLocation(), Constructor, FoundFn,
7712                                  Entity);
7713         if (S.DiagnoseUseOfDecl(FoundFn, Kind.getLocation()))
7714           return ExprError();
7715
7716         CastKind = CK_ConstructorConversion;
7717         CreatedObject = true;
7718       } else {
7719         // Build a call to the conversion function.
7720         CXXConversionDecl *Conversion = cast<CXXConversionDecl>(Fn);
7721         S.CheckMemberOperatorAccess(Kind.getLocation(), CurInit.get(), nullptr,
7722                                     FoundFn);
7723         if (S.DiagnoseUseOfDecl(FoundFn, Kind.getLocation()))
7724           return ExprError();
7725
7726         CurInit = S.BuildCXXMemberCallExpr(CurInit.get(), FoundFn, Conversion,
7727                                            HadMultipleCandidates);
7728         if (CurInit.isInvalid())
7729           return ExprError();
7730
7731         CastKind = CK_UserDefinedConversion;
7732         CreatedObject = Conversion->getReturnType()->isRecordType();
7733       }
7734
7735       if (CreatedObject && checkAbstractType(CurInit.get()->getType()))
7736         return ExprError();
7737
7738       CurInit = ImplicitCastExpr::Create(S.Context, CurInit.get()->getType(),
7739                                          CastKind, CurInit.get(), nullptr,
7740                                          CurInit.get()->getValueKind());
7741
7742       if (shouldBindAsTemporary(Entity))
7743         // The overall entity is temporary, so this expression should be
7744         // destroyed at the end of its full-expression.
7745         CurInit = S.MaybeBindToTemporary(CurInit.getAs<Expr>());
7746       else if (CreatedObject && shouldDestroyEntity(Entity)) {
7747         // The object outlasts the full-expression, but we need to prepare for
7748         // a destructor being run on it.
7749         // FIXME: It makes no sense to do this here. This should happen
7750         // regardless of how we initialized the entity.
7751         QualType T = CurInit.get()->getType();
7752         if (const RecordType *Record = T->getAs<RecordType>()) {
7753           CXXDestructorDecl *Destructor
7754             = S.LookupDestructor(cast<CXXRecordDecl>(Record->getDecl()));
7755           S.CheckDestructorAccess(CurInit.get()->getBeginLoc(), Destructor,
7756                                   S.PDiag(diag::err_access_dtor_temp) << T);
7757           S.MarkFunctionReferenced(CurInit.get()->getBeginLoc(), Destructor);
7758           if (S.DiagnoseUseOfDecl(Destructor, CurInit.get()->getBeginLoc()))
7759             return ExprError();
7760         }
7761       }
7762       break;
7763     }
7764
7765     case SK_QualificationConversionLValue:
7766     case SK_QualificationConversionXValue:
7767     case SK_QualificationConversionRValue: {
7768       // Perform a qualification conversion; these can never go wrong.
7769       ExprValueKind VK =
7770           Step->Kind == SK_QualificationConversionLValue
7771               ? VK_LValue
7772               : (Step->Kind == SK_QualificationConversionXValue ? VK_XValue
7773                                                                 : VK_RValue);
7774       CurInit = S.PerformQualificationConversion(CurInit.get(), Step->Type, VK);
7775       break;
7776     }
7777
7778     case SK_AtomicConversion: {
7779       assert(CurInit.get()->isRValue() && "cannot convert glvalue to atomic");
7780       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
7781                                     CK_NonAtomicToAtomic, VK_RValue);
7782       break;
7783     }
7784
7785     case SK_ConversionSequence:
7786     case SK_ConversionSequenceNoNarrowing: {
7787       if (const auto *FromPtrType =
7788               CurInit.get()->getType()->getAs<PointerType>()) {
7789         if (const auto *ToPtrType = Step->Type->getAs<PointerType>()) {
7790           if (FromPtrType->getPointeeType()->hasAttr(attr::NoDeref) &&
7791               !ToPtrType->getPointeeType()->hasAttr(attr::NoDeref)) {
7792             S.Diag(CurInit.get()->getExprLoc(),
7793                    diag::warn_noderef_to_dereferenceable_pointer)
7794                 << CurInit.get()->getSourceRange();
7795           }
7796         }
7797       }
7798
7799       Sema::CheckedConversionKind CCK
7800         = Kind.isCStyleCast()? Sema::CCK_CStyleCast
7801         : Kind.isFunctionalCast()? Sema::CCK_FunctionalCast
7802         : Kind.isExplicitCast()? Sema::CCK_OtherCast
7803         : Sema::CCK_ImplicitConversion;
7804       ExprResult CurInitExprRes =
7805         S.PerformImplicitConversion(CurInit.get(), Step->Type, *Step->ICS,
7806                                     getAssignmentAction(Entity), CCK);
7807       if (CurInitExprRes.isInvalid())
7808         return ExprError();
7809
7810       S.DiscardMisalignedMemberAddress(Step->Type.getTypePtr(), CurInit.get());
7811
7812       CurInit = CurInitExprRes;
7813
7814       if (Step->Kind == SK_ConversionSequenceNoNarrowing &&
7815           S.getLangOpts().CPlusPlus)
7816         DiagnoseNarrowingInInitList(S, *Step->ICS, SourceType, Entity.getType(),
7817                                     CurInit.get());
7818
7819       break;
7820     }
7821
7822     case SK_ListInitialization: {
7823       if (checkAbstractType(Step->Type))
7824         return ExprError();
7825
7826       InitListExpr *InitList = cast<InitListExpr>(CurInit.get());
7827       // If we're not initializing the top-level entity, we need to create an
7828       // InitializeTemporary entity for our target type.
7829       QualType Ty = Step->Type;
7830       bool IsTemporary = !S.Context.hasSameType(Entity.getType(), Ty);
7831       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(Ty);
7832       InitializedEntity InitEntity = IsTemporary ? TempEntity : Entity;
7833       InitListChecker PerformInitList(S, InitEntity,
7834           InitList, Ty, /*VerifyOnly=*/false,
7835           /*TreatUnavailableAsInvalid=*/false);
7836       if (PerformInitList.HadError())
7837         return ExprError();
7838
7839       // Hack: We must update *ResultType if available in order to set the
7840       // bounds of arrays, e.g. in 'int ar[] = {1, 2, 3};'.
7841       // Worst case: 'const int (&arref)[] = {1, 2, 3};'.
7842       if (ResultType &&
7843           ResultType->getNonReferenceType()->isIncompleteArrayType()) {
7844         if ((*ResultType)->isRValueReferenceType())
7845           Ty = S.Context.getRValueReferenceType(Ty);
7846         else if ((*ResultType)->isLValueReferenceType())
7847           Ty = S.Context.getLValueReferenceType(Ty,
7848             (*ResultType)->getAs<LValueReferenceType>()->isSpelledAsLValue());
7849         *ResultType = Ty;
7850       }
7851
7852       InitListExpr *StructuredInitList =
7853           PerformInitList.getFullyStructuredList();
7854       CurInit.get();
7855       CurInit = shouldBindAsTemporary(InitEntity)
7856           ? S.MaybeBindToTemporary(StructuredInitList)
7857           : StructuredInitList;
7858       break;
7859     }
7860
7861     case SK_ConstructorInitializationFromList: {
7862       if (checkAbstractType(Step->Type))
7863         return ExprError();
7864
7865       // When an initializer list is passed for a parameter of type "reference
7866       // to object", we don't get an EK_Temporary entity, but instead an
7867       // EK_Parameter entity with reference type.
7868       // FIXME: This is a hack. What we really should do is create a user
7869       // conversion step for this case, but this makes it considerably more
7870       // complicated. For now, this will do.
7871       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(
7872                                         Entity.getType().getNonReferenceType());
7873       bool UseTemporary = Entity.getType()->isReferenceType();
7874       assert(Args.size() == 1 && "expected a single argument for list init");
7875       InitListExpr *InitList = cast<InitListExpr>(Args[0]);
7876       S.Diag(InitList->getExprLoc(), diag::warn_cxx98_compat_ctor_list_init)
7877         << InitList->getSourceRange();
7878       MultiExprArg Arg(InitList->getInits(), InitList->getNumInits());
7879       CurInit = PerformConstructorInitialization(S, UseTemporary ? TempEntity :
7880                                                                    Entity,
7881                                                  Kind, Arg, *Step,
7882                                                ConstructorInitRequiresZeroInit,
7883                                                /*IsListInitialization*/true,
7884                                                /*IsStdInitListInit*/false,
7885                                                InitList->getLBraceLoc(),
7886                                                InitList->getRBraceLoc());
7887       break;
7888     }
7889
7890     case SK_UnwrapInitList:
7891       CurInit = cast<InitListExpr>(CurInit.get())->getInit(0);
7892       break;
7893
7894     case SK_RewrapInitList: {
7895       Expr *E = CurInit.get();
7896       InitListExpr *Syntactic = Step->WrappingSyntacticList;
7897       InitListExpr *ILE = new (S.Context) InitListExpr(S.Context,
7898           Syntactic->getLBraceLoc(), E, Syntactic->getRBraceLoc());
7899       ILE->setSyntacticForm(Syntactic);
7900       ILE->setType(E->getType());
7901       ILE->setValueKind(E->getValueKind());
7902       CurInit = ILE;
7903       break;
7904     }
7905
7906     case SK_ConstructorInitialization:
7907     case SK_StdInitializerListConstructorCall: {
7908       if (checkAbstractType(Step->Type))
7909         return ExprError();
7910
7911       // When an initializer list is passed for a parameter of type "reference
7912       // to object", we don't get an EK_Temporary entity, but instead an
7913       // EK_Parameter entity with reference type.
7914       // FIXME: This is a hack. What we really should do is create a user
7915       // conversion step for this case, but this makes it considerably more
7916       // complicated. For now, this will do.
7917       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(
7918                                         Entity.getType().getNonReferenceType());
7919       bool UseTemporary = Entity.getType()->isReferenceType();
7920       bool IsStdInitListInit =
7921           Step->Kind == SK_StdInitializerListConstructorCall;
7922       Expr *Source = CurInit.get();
7923       SourceRange Range = Kind.hasParenOrBraceRange()
7924                               ? Kind.getParenOrBraceRange()
7925                               : SourceRange();
7926       CurInit = PerformConstructorInitialization(
7927           S, UseTemporary ? TempEntity : Entity, Kind,
7928           Source ? MultiExprArg(Source) : Args, *Step,
7929           ConstructorInitRequiresZeroInit,
7930           /*IsListInitialization*/ IsStdInitListInit,
7931           /*IsStdInitListInitialization*/ IsStdInitListInit,
7932           /*LBraceLoc*/ Range.getBegin(),
7933           /*RBraceLoc*/ Range.getEnd());
7934       break;
7935     }
7936
7937     case SK_ZeroInitialization: {
7938       step_iterator NextStep = Step;
7939       ++NextStep;
7940       if (NextStep != StepEnd &&
7941           (NextStep->Kind == SK_ConstructorInitialization ||
7942            NextStep->Kind == SK_ConstructorInitializationFromList)) {
7943         // The need for zero-initialization is recorded directly into
7944         // the call to the object's constructor within the next step.
7945         ConstructorInitRequiresZeroInit = true;
7946       } else if (Kind.getKind() == InitializationKind::IK_Value &&
7947                  S.getLangOpts().CPlusPlus &&
7948                  !Kind.isImplicitValueInit()) {
7949         TypeSourceInfo *TSInfo = Entity.getTypeSourceInfo();
7950         if (!TSInfo)
7951           TSInfo = S.Context.getTrivialTypeSourceInfo(Step->Type,
7952                                                     Kind.getRange().getBegin());
7953
7954         CurInit = new (S.Context) CXXScalarValueInitExpr(
7955             Entity.getType().getNonLValueExprType(S.Context), TSInfo,
7956             Kind.getRange().getEnd());
7957       } else {
7958         CurInit = new (S.Context) ImplicitValueInitExpr(Step->Type);
7959       }
7960       break;
7961     }
7962
7963     case SK_CAssignment: {
7964       QualType SourceType = CurInit.get()->getType();
7965
7966       // Save off the initial CurInit in case we need to emit a diagnostic
7967       ExprResult InitialCurInit = CurInit;
7968       ExprResult Result = CurInit;
7969       Sema::AssignConvertType ConvTy =
7970         S.CheckSingleAssignmentConstraints(Step->Type, Result, true,
7971             Entity.getKind() == InitializedEntity::EK_Parameter_CF_Audited);
7972       if (Result.isInvalid())
7973         return ExprError();
7974       CurInit = Result;
7975
7976       // If this is a call, allow conversion to a transparent union.
7977       ExprResult CurInitExprRes = CurInit;
7978       if (ConvTy != Sema::Compatible &&
7979           Entity.isParameterKind() &&
7980           S.CheckTransparentUnionArgumentConstraints(Step->Type, CurInitExprRes)
7981             == Sema::Compatible)
7982         ConvTy = Sema::Compatible;
7983       if (CurInitExprRes.isInvalid())
7984         return ExprError();
7985       CurInit = CurInitExprRes;
7986
7987       bool Complained;
7988       if (S.DiagnoseAssignmentResult(ConvTy, Kind.getLocation(),
7989                                      Step->Type, SourceType,
7990                                      InitialCurInit.get(),
7991                                      getAssignmentAction(Entity, true),
7992                                      &Complained)) {
7993         PrintInitLocationNote(S, Entity);
7994         return ExprError();
7995       } else if (Complained)
7996         PrintInitLocationNote(S, Entity);
7997       break;
7998     }
7999
8000     case SK_StringInit: {
8001       QualType Ty = Step->Type;
8002       CheckStringInit(CurInit.get(), ResultType ? *ResultType : Ty,
8003                       S.Context.getAsArrayType(Ty), S);
8004       break;
8005     }
8006
8007     case SK_ObjCObjectConversion:
8008       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
8009                           CK_ObjCObjectLValueCast,
8010                           CurInit.get()->getValueKind());
8011       break;
8012
8013     case SK_ArrayLoopIndex: {
8014       Expr *Cur = CurInit.get();
8015       Expr *BaseExpr = new (S.Context)
8016           OpaqueValueExpr(Cur->getExprLoc(), Cur->getType(),
8017                           Cur->getValueKind(), Cur->getObjectKind(), Cur);
8018       Expr *IndexExpr =
8019           new (S.Context) ArrayInitIndexExpr(S.Context.getSizeType());
8020       CurInit = S.CreateBuiltinArraySubscriptExpr(
8021           BaseExpr, Kind.getLocation(), IndexExpr, Kind.getLocation());
8022       ArrayLoopCommonExprs.push_back(BaseExpr);
8023       break;
8024     }
8025
8026     case SK_ArrayLoopInit: {
8027       assert(!ArrayLoopCommonExprs.empty() &&
8028              "mismatched SK_ArrayLoopIndex and SK_ArrayLoopInit");
8029       Expr *Common = ArrayLoopCommonExprs.pop_back_val();
8030       CurInit = new (S.Context) ArrayInitLoopExpr(Step->Type, Common,
8031                                                   CurInit.get());
8032       break;
8033     }
8034
8035     case SK_GNUArrayInit:
8036       // Okay: we checked everything before creating this step. Note that
8037       // this is a GNU extension.
8038       S.Diag(Kind.getLocation(), diag::ext_array_init_copy)
8039         << Step->Type << CurInit.get()->getType()
8040         << CurInit.get()->getSourceRange();
8041       updateGNUCompoundLiteralRValue(CurInit.get());
8042       LLVM_FALLTHROUGH;
8043     case SK_ArrayInit:
8044       // If the destination type is an incomplete array type, update the
8045       // type accordingly.
8046       if (ResultType) {
8047         if (const IncompleteArrayType *IncompleteDest
8048                            = S.Context.getAsIncompleteArrayType(Step->Type)) {
8049           if (const ConstantArrayType *ConstantSource
8050                  = S.Context.getAsConstantArrayType(CurInit.get()->getType())) {
8051             *ResultType = S.Context.getConstantArrayType(
8052                                              IncompleteDest->getElementType(),
8053                                              ConstantSource->getSize(),
8054                                              ArrayType::Normal, 0);
8055           }
8056         }
8057       }
8058       break;
8059
8060     case SK_ParenthesizedArrayInit:
8061       // Okay: we checked everything before creating this step. Note that
8062       // this is a GNU extension.
8063       S.Diag(Kind.getLocation(), diag::ext_array_init_parens)
8064         << CurInit.get()->getSourceRange();
8065       break;
8066
8067     case SK_PassByIndirectCopyRestore:
8068     case SK_PassByIndirectRestore:
8069       checkIndirectCopyRestoreSource(S, CurInit.get());
8070       CurInit = new (S.Context) ObjCIndirectCopyRestoreExpr(
8071           CurInit.get(), Step->Type,
8072           Step->Kind == SK_PassByIndirectCopyRestore);
8073       break;
8074
8075     case SK_ProduceObjCObject:
8076       CurInit =
8077           ImplicitCastExpr::Create(S.Context, Step->Type, CK_ARCProduceObject,
8078                                    CurInit.get(), nullptr, VK_RValue);
8079       break;
8080
8081     case SK_StdInitializerList: {
8082       S.Diag(CurInit.get()->getExprLoc(),
8083              diag::warn_cxx98_compat_initializer_list_init)
8084         << CurInit.get()->getSourceRange();
8085
8086       // Materialize the temporary into memory.
8087       MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
8088           CurInit.get()->getType(), CurInit.get(),
8089           /*BoundToLvalueReference=*/false);
8090
8091       // Wrap it in a construction of a std::initializer_list<T>.
8092       CurInit = new (S.Context) CXXStdInitializerListExpr(Step->Type, MTE);
8093
8094       // Bind the result, in case the library has given initializer_list a
8095       // non-trivial destructor.
8096       if (shouldBindAsTemporary(Entity))
8097         CurInit = S.MaybeBindToTemporary(CurInit.get());
8098       break;
8099     }
8100
8101     case SK_OCLSamplerInit: {
8102       // Sampler initialization have 5 cases:
8103       //   1. function argument passing
8104       //      1a. argument is a file-scope variable
8105       //      1b. argument is a function-scope variable
8106       //      1c. argument is one of caller function's parameters
8107       //   2. variable initialization
8108       //      2a. initializing a file-scope variable
8109       //      2b. initializing a function-scope variable
8110       //
8111       // For file-scope variables, since they cannot be initialized by function
8112       // call of __translate_sampler_initializer in LLVM IR, their references
8113       // need to be replaced by a cast from their literal initializers to
8114       // sampler type. Since sampler variables can only be used in function
8115       // calls as arguments, we only need to replace them when handling the
8116       // argument passing.
8117       assert(Step->Type->isSamplerT() &&
8118              "Sampler initialization on non-sampler type.");
8119       Expr *Init = CurInit.get()->IgnoreParens();
8120       QualType SourceType = Init->getType();
8121       // Case 1
8122       if (Entity.isParameterKind()) {
8123         if (!SourceType->isSamplerT() && !SourceType->isIntegerType()) {
8124           S.Diag(Kind.getLocation(), diag::err_sampler_argument_required)
8125             << SourceType;
8126           break;
8127         } else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Init)) {
8128           auto Var = cast<VarDecl>(DRE->getDecl());
8129           // Case 1b and 1c
8130           // No cast from integer to sampler is needed.
8131           if (!Var->hasGlobalStorage()) {
8132             CurInit = ImplicitCastExpr::Create(S.Context, Step->Type,
8133                                                CK_LValueToRValue, Init,
8134                                                /*BasePath=*/nullptr, VK_RValue);
8135             break;
8136           }
8137           // Case 1a
8138           // For function call with a file-scope sampler variable as argument,
8139           // get the integer literal.
8140           // Do not diagnose if the file-scope variable does not have initializer
8141           // since this has already been diagnosed when parsing the variable
8142           // declaration.
8143           if (!Var->getInit() || !isa<ImplicitCastExpr>(Var->getInit()))
8144             break;
8145           Init = cast<ImplicitCastExpr>(const_cast<Expr*>(
8146             Var->getInit()))->getSubExpr();
8147           SourceType = Init->getType();
8148         }
8149       } else {
8150         // Case 2
8151         // Check initializer is 32 bit integer constant.
8152         // If the initializer is taken from global variable, do not diagnose since
8153         // this has already been done when parsing the variable declaration.
8154         if (!Init->isConstantInitializer(S.Context, false))
8155           break;
8156
8157         if (!SourceType->isIntegerType() ||
8158             32 != S.Context.getIntWidth(SourceType)) {
8159           S.Diag(Kind.getLocation(), diag::err_sampler_initializer_not_integer)
8160             << SourceType;
8161           break;
8162         }
8163
8164         Expr::EvalResult EVResult;
8165         Init->EvaluateAsInt(EVResult, S.Context);
8166         llvm::APSInt Result = EVResult.Val.getInt();
8167         const uint64_t SamplerValue = Result.getLimitedValue();
8168         // 32-bit value of sampler's initializer is interpreted as
8169         // bit-field with the following structure:
8170         // |unspecified|Filter|Addressing Mode| Normalized Coords|
8171         // |31        6|5    4|3             1|                 0|
8172         // This structure corresponds to enum values of sampler properties
8173         // defined in SPIR spec v1.2 and also opencl-c.h
8174         unsigned AddressingMode  = (0x0E & SamplerValue) >> 1;
8175         unsigned FilterMode      = (0x30 & SamplerValue) >> 4;
8176         if (FilterMode != 1 && FilterMode != 2 &&
8177             !S.getOpenCLOptions().isEnabled(
8178                 "cl_intel_device_side_avc_motion_estimation"))
8179           S.Diag(Kind.getLocation(),
8180                  diag::warn_sampler_initializer_invalid_bits)
8181                  << "Filter Mode";
8182         if (AddressingMode > 4)
8183           S.Diag(Kind.getLocation(),
8184                  diag::warn_sampler_initializer_invalid_bits)
8185                  << "Addressing Mode";
8186       }
8187
8188       // Cases 1a, 2a and 2b
8189       // Insert cast from integer to sampler.
8190       CurInit = S.ImpCastExprToType(Init, S.Context.OCLSamplerTy,
8191                                       CK_IntToOCLSampler);
8192       break;
8193     }
8194     case SK_OCLZeroOpaqueType: {
8195       assert((Step->Type->isEventT() || Step->Type->isQueueT() ||
8196               Step->Type->isOCLIntelSubgroupAVCType()) &&
8197              "Wrong type for initialization of OpenCL opaque type.");
8198
8199       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
8200                                     CK_ZeroToOCLOpaqueType,
8201                                     CurInit.get()->getValueKind());
8202       break;
8203     }
8204     }
8205   }
8206
8207   // Check whether the initializer has a shorter lifetime than the initialized
8208   // entity, and if not, either lifetime-extend or warn as appropriate.
8209   if (auto *Init = CurInit.get())
8210     S.checkInitializerLifetime(Entity, Init);
8211
8212   // Diagnose non-fatal problems with the completed initialization.
8213   if (Entity.getKind() == InitializedEntity::EK_Member &&
8214       cast<FieldDecl>(Entity.getDecl())->isBitField())
8215     S.CheckBitFieldInitialization(Kind.getLocation(),
8216                                   cast<FieldDecl>(Entity.getDecl()),
8217                                   CurInit.get());
8218
8219   // Check for std::move on construction.
8220   if (const Expr *E = CurInit.get()) {
8221     CheckMoveOnConstruction(S, E,
8222                             Entity.getKind() == InitializedEntity::EK_Result);
8223   }
8224
8225   return CurInit;
8226 }
8227
8228 /// Somewhere within T there is an uninitialized reference subobject.
8229 /// Dig it out and diagnose it.
8230 static bool DiagnoseUninitializedReference(Sema &S, SourceLocation Loc,
8231                                            QualType T) {
8232   if (T->isReferenceType()) {
8233     S.Diag(Loc, diag::err_reference_without_init)
8234       << T.getNonReferenceType();
8235     return true;
8236   }
8237
8238   CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
8239   if (!RD || !RD->hasUninitializedReferenceMember())
8240     return false;
8241
8242   for (const auto *FI : RD->fields()) {
8243     if (FI->isUnnamedBitfield())
8244       continue;
8245
8246     if (DiagnoseUninitializedReference(S, FI->getLocation(), FI->getType())) {
8247       S.Diag(Loc, diag::note_value_initialization_here) << RD;
8248       return true;
8249     }
8250   }
8251
8252   for (const auto &BI : RD->bases()) {
8253     if (DiagnoseUninitializedReference(S, BI.getBeginLoc(), BI.getType())) {
8254       S.Diag(Loc, diag::note_value_initialization_here) << RD;
8255       return true;
8256     }
8257   }
8258
8259   return false;
8260 }
8261
8262
8263 //===----------------------------------------------------------------------===//
8264 // Diagnose initialization failures
8265 //===----------------------------------------------------------------------===//
8266
8267 /// Emit notes associated with an initialization that failed due to a
8268 /// "simple" conversion failure.
8269 static void emitBadConversionNotes(Sema &S, const InitializedEntity &entity,
8270                                    Expr *op) {
8271   QualType destType = entity.getType();
8272   if (destType.getNonReferenceType()->isObjCObjectPointerType() &&
8273       op->getType()->isObjCObjectPointerType()) {
8274
8275     // Emit a possible note about the conversion failing because the
8276     // operand is a message send with a related result type.
8277     S.EmitRelatedResultTypeNote(op);
8278
8279     // Emit a possible note about a return failing because we're
8280     // expecting a related result type.
8281     if (entity.getKind() == InitializedEntity::EK_Result)
8282       S.EmitRelatedResultTypeNoteForReturn(destType);
8283   }
8284 }
8285
8286 static void diagnoseListInit(Sema &S, const InitializedEntity &Entity,
8287                              InitListExpr *InitList) {
8288   QualType DestType = Entity.getType();
8289
8290   QualType E;
8291   if (S.getLangOpts().CPlusPlus11 && S.isStdInitializerList(DestType, &E)) {
8292     QualType ArrayType = S.Context.getConstantArrayType(
8293         E.withConst(),
8294         llvm::APInt(S.Context.getTypeSize(S.Context.getSizeType()),
8295                     InitList->getNumInits()),
8296         clang::ArrayType::Normal, 0);
8297     InitializedEntity HiddenArray =
8298         InitializedEntity::InitializeTemporary(ArrayType);
8299     return diagnoseListInit(S, HiddenArray, InitList);
8300   }
8301
8302   if (DestType->isReferenceType()) {
8303     // A list-initialization failure for a reference means that we tried to
8304     // create a temporary of the inner type (per [dcl.init.list]p3.6) and the
8305     // inner initialization failed.
8306     QualType T = DestType->getAs<ReferenceType>()->getPointeeType();
8307     diagnoseListInit(S, InitializedEntity::InitializeTemporary(T), InitList);
8308     SourceLocation Loc = InitList->getBeginLoc();
8309     if (auto *D = Entity.getDecl())
8310       Loc = D->getLocation();
8311     S.Diag(Loc, diag::note_in_reference_temporary_list_initializer) << T;
8312     return;
8313   }
8314
8315   InitListChecker DiagnoseInitList(S, Entity, InitList, DestType,
8316                                    /*VerifyOnly=*/false,
8317                                    /*TreatUnavailableAsInvalid=*/false);
8318   assert(DiagnoseInitList.HadError() &&
8319          "Inconsistent init list check result.");
8320 }
8321
8322 bool InitializationSequence::Diagnose(Sema &S,
8323                                       const InitializedEntity &Entity,
8324                                       const InitializationKind &Kind,
8325                                       ArrayRef<Expr *> Args) {
8326   if (!Failed())
8327     return false;
8328
8329   // When we want to diagnose only one element of a braced-init-list,
8330   // we need to factor it out.
8331   Expr *OnlyArg;
8332   if (Args.size() == 1) {
8333     auto *List = dyn_cast<InitListExpr>(Args[0]);
8334     if (List && List->getNumInits() == 1)
8335       OnlyArg = List->getInit(0);
8336     else
8337       OnlyArg = Args[0];
8338   }
8339   else
8340     OnlyArg = nullptr;
8341
8342   QualType DestType = Entity.getType();
8343   switch (Failure) {
8344   case FK_TooManyInitsForReference:
8345     // FIXME: Customize for the initialized entity?
8346     if (Args.empty()) {
8347       // Dig out the reference subobject which is uninitialized and diagnose it.
8348       // If this is value-initialization, this could be nested some way within
8349       // the target type.
8350       assert(Kind.getKind() == InitializationKind::IK_Value ||
8351              DestType->isReferenceType());
8352       bool Diagnosed =
8353         DiagnoseUninitializedReference(S, Kind.getLocation(), DestType);
8354       assert(Diagnosed && "couldn't find uninitialized reference to diagnose");
8355       (void)Diagnosed;
8356     } else  // FIXME: diagnostic below could be better!
8357       S.Diag(Kind.getLocation(), diag::err_reference_has_multiple_inits)
8358           << SourceRange(Args.front()->getBeginLoc(), Args.back()->getEndLoc());
8359     break;
8360   case FK_ParenthesizedListInitForReference:
8361     S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
8362       << 1 << Entity.getType() << Args[0]->getSourceRange();
8363     break;
8364
8365   case FK_ArrayNeedsInitList:
8366     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 0;
8367     break;
8368   case FK_ArrayNeedsInitListOrStringLiteral:
8369     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 1;
8370     break;
8371   case FK_ArrayNeedsInitListOrWideStringLiteral:
8372     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 2;
8373     break;
8374   case FK_NarrowStringIntoWideCharArray:
8375     S.Diag(Kind.getLocation(), diag::err_array_init_narrow_string_into_wchar);
8376     break;
8377   case FK_WideStringIntoCharArray:
8378     S.Diag(Kind.getLocation(), diag::err_array_init_wide_string_into_char);
8379     break;
8380   case FK_IncompatWideStringIntoWideChar:
8381     S.Diag(Kind.getLocation(),
8382            diag::err_array_init_incompat_wide_string_into_wchar);
8383     break;
8384   case FK_PlainStringIntoUTF8Char:
8385     S.Diag(Kind.getLocation(),
8386            diag::err_array_init_plain_string_into_char8_t);
8387     S.Diag(Args.front()->getBeginLoc(),
8388            diag::note_array_init_plain_string_into_char8_t)
8389         << FixItHint::CreateInsertion(Args.front()->getBeginLoc(), "u8");
8390     break;
8391   case FK_UTF8StringIntoPlainChar:
8392     S.Diag(Kind.getLocation(),
8393            diag::err_array_init_utf8_string_into_char)
8394       << S.getLangOpts().CPlusPlus2a;
8395     break;
8396   case FK_ArrayTypeMismatch:
8397   case FK_NonConstantArrayInit:
8398     S.Diag(Kind.getLocation(),
8399            (Failure == FK_ArrayTypeMismatch
8400               ? diag::err_array_init_different_type
8401               : diag::err_array_init_non_constant_array))
8402       << DestType.getNonReferenceType()
8403       << OnlyArg->getType()
8404       << Args[0]->getSourceRange();
8405     break;
8406
8407   case FK_VariableLengthArrayHasInitializer:
8408     S.Diag(Kind.getLocation(), diag::err_variable_object_no_init)
8409       << Args[0]->getSourceRange();
8410     break;
8411
8412   case FK_AddressOfOverloadFailed: {
8413     DeclAccessPair Found;
8414     S.ResolveAddressOfOverloadedFunction(OnlyArg,
8415                                          DestType.getNonReferenceType(),
8416                                          true,
8417                                          Found);
8418     break;
8419   }
8420
8421   case FK_AddressOfUnaddressableFunction: {
8422     auto *FD = cast<FunctionDecl>(cast<DeclRefExpr>(OnlyArg)->getDecl());
8423     S.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
8424                                         OnlyArg->getBeginLoc());
8425     break;
8426   }
8427
8428   case FK_ReferenceInitOverloadFailed:
8429   case FK_UserConversionOverloadFailed:
8430     switch (FailedOverloadResult) {
8431     case OR_Ambiguous:
8432
8433       FailedCandidateSet.NoteCandidates(
8434           PartialDiagnosticAt(
8435               Kind.getLocation(),
8436               Failure == FK_UserConversionOverloadFailed
8437                   ? (S.PDiag(diag::err_typecheck_ambiguous_condition)
8438                      << OnlyArg->getType() << DestType
8439                      << Args[0]->getSourceRange())
8440                   : (S.PDiag(diag::err_ref_init_ambiguous)
8441                      << DestType << OnlyArg->getType()
8442                      << Args[0]->getSourceRange())),
8443           S, OCD_ViableCandidates, Args);
8444       break;
8445
8446     case OR_No_Viable_Function: {
8447       auto Cands = FailedCandidateSet.CompleteCandidates(S, OCD_AllCandidates, Args);
8448       if (!S.RequireCompleteType(Kind.getLocation(),
8449                                  DestType.getNonReferenceType(),
8450                           diag::err_typecheck_nonviable_condition_incomplete,
8451                                OnlyArg->getType(), Args[0]->getSourceRange()))
8452         S.Diag(Kind.getLocation(), diag::err_typecheck_nonviable_condition)
8453           << (Entity.getKind() == InitializedEntity::EK_Result)
8454           << OnlyArg->getType() << Args[0]->getSourceRange()
8455           << DestType.getNonReferenceType();
8456
8457       FailedCandidateSet.NoteCandidates(S, Args, Cands);
8458       break;
8459     }
8460     case OR_Deleted: {
8461       S.Diag(Kind.getLocation(), diag::err_typecheck_deleted_function)
8462         << OnlyArg->getType() << DestType.getNonReferenceType()
8463         << Args[0]->getSourceRange();
8464       OverloadCandidateSet::iterator Best;
8465       OverloadingResult Ovl
8466         = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
8467       if (Ovl == OR_Deleted) {
8468         S.NoteDeletedFunction(Best->Function);
8469       } else {
8470         llvm_unreachable("Inconsistent overload resolution?");
8471       }
8472       break;
8473     }
8474
8475     case OR_Success:
8476       llvm_unreachable("Conversion did not fail!");
8477     }
8478     break;
8479
8480   case FK_NonConstLValueReferenceBindingToTemporary:
8481     if (isa<InitListExpr>(Args[0])) {
8482       S.Diag(Kind.getLocation(),
8483              diag::err_lvalue_reference_bind_to_initlist)
8484       << DestType.getNonReferenceType().isVolatileQualified()
8485       << DestType.getNonReferenceType()
8486       << Args[0]->getSourceRange();
8487       break;
8488     }
8489     LLVM_FALLTHROUGH;
8490
8491   case FK_NonConstLValueReferenceBindingToUnrelated:
8492     S.Diag(Kind.getLocation(),
8493            Failure == FK_NonConstLValueReferenceBindingToTemporary
8494              ? diag::err_lvalue_reference_bind_to_temporary
8495              : diag::err_lvalue_reference_bind_to_unrelated)
8496       << DestType.getNonReferenceType().isVolatileQualified()
8497       << DestType.getNonReferenceType()
8498       << OnlyArg->getType()
8499       << Args[0]->getSourceRange();
8500     break;
8501
8502   case FK_NonConstLValueReferenceBindingToBitfield: {
8503     // We don't necessarily have an unambiguous source bit-field.
8504     FieldDecl *BitField = Args[0]->getSourceBitField();
8505     S.Diag(Kind.getLocation(), diag::err_reference_bind_to_bitfield)
8506       << DestType.isVolatileQualified()
8507       << (BitField ? BitField->getDeclName() : DeclarationName())
8508       << (BitField != nullptr)
8509       << Args[0]->getSourceRange();
8510     if (BitField)
8511       S.Diag(BitField->getLocation(), diag::note_bitfield_decl);
8512     break;
8513   }
8514
8515   case FK_NonConstLValueReferenceBindingToVectorElement:
8516     S.Diag(Kind.getLocation(), diag::err_reference_bind_to_vector_element)
8517       << DestType.isVolatileQualified()
8518       << Args[0]->getSourceRange();
8519     break;
8520
8521   case FK_RValueReferenceBindingToLValue:
8522     S.Diag(Kind.getLocation(), diag::err_lvalue_to_rvalue_ref)
8523       << DestType.getNonReferenceType() << OnlyArg->getType()
8524       << Args[0]->getSourceRange();
8525     break;
8526
8527   case FK_ReferenceAddrspaceMismatchTemporary:
8528     S.Diag(Kind.getLocation(), diag::err_reference_bind_temporary_addrspace)
8529         << DestType << Args[0]->getSourceRange();
8530     break;
8531
8532   case FK_ReferenceInitDropsQualifiers: {
8533     QualType SourceType = OnlyArg->getType();
8534     QualType NonRefType = DestType.getNonReferenceType();
8535     Qualifiers DroppedQualifiers =
8536         SourceType.getQualifiers() - NonRefType.getQualifiers();
8537
8538     if (!NonRefType.getQualifiers().isAddressSpaceSupersetOf(
8539             SourceType.getQualifiers()))
8540       S.Diag(Kind.getLocation(), diag::err_reference_bind_drops_quals)
8541           << NonRefType << SourceType << 1 /*addr space*/
8542           << Args[0]->getSourceRange();
8543     else
8544       S.Diag(Kind.getLocation(), diag::err_reference_bind_drops_quals)
8545           << NonRefType << SourceType << 0 /*cv quals*/
8546           << Qualifiers::fromCVRMask(DroppedQualifiers.getCVRQualifiers())
8547           << DroppedQualifiers.getCVRQualifiers() << Args[0]->getSourceRange();
8548     break;
8549   }
8550
8551   case FK_ReferenceInitFailed:
8552     S.Diag(Kind.getLocation(), diag::err_reference_bind_failed)
8553       << DestType.getNonReferenceType()
8554       << DestType.getNonReferenceType()->isIncompleteType()
8555       << OnlyArg->isLValue()
8556       << OnlyArg->getType()
8557       << Args[0]->getSourceRange();
8558     emitBadConversionNotes(S, Entity, Args[0]);
8559     break;
8560
8561   case FK_ConversionFailed: {
8562     QualType FromType = OnlyArg->getType();
8563     PartialDiagnostic PDiag = S.PDiag(diag::err_init_conversion_failed)
8564       << (int)Entity.getKind()
8565       << DestType
8566       << OnlyArg->isLValue()
8567       << FromType
8568       << Args[0]->getSourceRange();
8569     S.HandleFunctionTypeMismatch(PDiag, FromType, DestType);
8570     S.Diag(Kind.getLocation(), PDiag);
8571     emitBadConversionNotes(S, Entity, Args[0]);
8572     break;
8573   }
8574
8575   case FK_ConversionFromPropertyFailed:
8576     // No-op. This error has already been reported.
8577     break;
8578
8579   case FK_TooManyInitsForScalar: {
8580     SourceRange R;
8581
8582     auto *InitList = dyn_cast<InitListExpr>(Args[0]);
8583     if (InitList && InitList->getNumInits() >= 1) {
8584       R = SourceRange(InitList->getInit(0)->getEndLoc(), InitList->getEndLoc());
8585     } else {
8586       assert(Args.size() > 1 && "Expected multiple initializers!");
8587       R = SourceRange(Args.front()->getEndLoc(), Args.back()->getEndLoc());
8588     }
8589
8590     R.setBegin(S.getLocForEndOfToken(R.getBegin()));
8591     if (Kind.isCStyleOrFunctionalCast())
8592       S.Diag(Kind.getLocation(), diag::err_builtin_func_cast_more_than_one_arg)
8593         << R;
8594     else
8595       S.Diag(Kind.getLocation(), diag::err_excess_initializers)
8596         << /*scalar=*/2 << R;
8597     break;
8598   }
8599
8600   case FK_ParenthesizedListInitForScalar:
8601     S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
8602       << 0 << Entity.getType() << Args[0]->getSourceRange();
8603     break;
8604
8605   case FK_ReferenceBindingToInitList:
8606     S.Diag(Kind.getLocation(), diag::err_reference_bind_init_list)
8607       << DestType.getNonReferenceType() << Args[0]->getSourceRange();
8608     break;
8609
8610   case FK_InitListBadDestinationType:
8611     S.Diag(Kind.getLocation(), diag::err_init_list_bad_dest_type)
8612       << (DestType->isRecordType()) << DestType << Args[0]->getSourceRange();
8613     break;
8614
8615   case FK_ListConstructorOverloadFailed:
8616   case FK_ConstructorOverloadFailed: {
8617     SourceRange ArgsRange;
8618     if (Args.size())
8619       ArgsRange =
8620           SourceRange(Args.front()->getBeginLoc(), Args.back()->getEndLoc());
8621
8622     if (Failure == FK_ListConstructorOverloadFailed) {
8623       assert(Args.size() == 1 &&
8624              "List construction from other than 1 argument.");
8625       InitListExpr *InitList = cast<InitListExpr>(Args[0]);
8626       Args = MultiExprArg(InitList->getInits(), InitList->getNumInits());
8627     }
8628
8629     // FIXME: Using "DestType" for the entity we're printing is probably
8630     // bad.
8631     switch (FailedOverloadResult) {
8632       case OR_Ambiguous:
8633         FailedCandidateSet.NoteCandidates(
8634             PartialDiagnosticAt(Kind.getLocation(),
8635                                 S.PDiag(diag::err_ovl_ambiguous_init)
8636                                     << DestType << ArgsRange),
8637             S, OCD_ViableCandidates, Args);
8638         break;
8639
8640       case OR_No_Viable_Function:
8641         if (Kind.getKind() == InitializationKind::IK_Default &&
8642             (Entity.getKind() == InitializedEntity::EK_Base ||
8643              Entity.getKind() == InitializedEntity::EK_Member) &&
8644             isa<CXXConstructorDecl>(S.CurContext)) {
8645           // This is implicit default initialization of a member or
8646           // base within a constructor. If no viable function was
8647           // found, notify the user that they need to explicitly
8648           // initialize this base/member.
8649           CXXConstructorDecl *Constructor
8650             = cast<CXXConstructorDecl>(S.CurContext);
8651           const CXXRecordDecl *InheritedFrom = nullptr;
8652           if (auto Inherited = Constructor->getInheritedConstructor())
8653             InheritedFrom = Inherited.getShadowDecl()->getNominatedBaseClass();
8654           if (Entity.getKind() == InitializedEntity::EK_Base) {
8655             S.Diag(Kind.getLocation(), diag::err_missing_default_ctor)
8656               << (InheritedFrom ? 2 : Constructor->isImplicit() ? 1 : 0)
8657               << S.Context.getTypeDeclType(Constructor->getParent())
8658               << /*base=*/0
8659               << Entity.getType()
8660               << InheritedFrom;
8661
8662             RecordDecl *BaseDecl
8663               = Entity.getBaseSpecifier()->getType()->getAs<RecordType>()
8664                                                                   ->getDecl();
8665             S.Diag(BaseDecl->getLocation(), diag::note_previous_decl)
8666               << S.Context.getTagDeclType(BaseDecl);
8667           } else {
8668             S.Diag(Kind.getLocation(), diag::err_missing_default_ctor)
8669               << (InheritedFrom ? 2 : Constructor->isImplicit() ? 1 : 0)
8670               << S.Context.getTypeDeclType(Constructor->getParent())
8671               << /*member=*/1
8672               << Entity.getName()
8673               << InheritedFrom;
8674             S.Diag(Entity.getDecl()->getLocation(),
8675                    diag::note_member_declared_at);
8676
8677             if (const RecordType *Record
8678                                  = Entity.getType()->getAs<RecordType>())
8679               S.Diag(Record->getDecl()->getLocation(),
8680                      diag::note_previous_decl)
8681                 << S.Context.getTagDeclType(Record->getDecl());
8682           }
8683           break;
8684         }
8685
8686         FailedCandidateSet.NoteCandidates(
8687             PartialDiagnosticAt(
8688                 Kind.getLocation(),
8689                 S.PDiag(diag::err_ovl_no_viable_function_in_init)
8690                     << DestType << ArgsRange),
8691             S, OCD_AllCandidates, Args);
8692         break;
8693
8694       case OR_Deleted: {
8695         OverloadCandidateSet::iterator Best;
8696         OverloadingResult Ovl
8697           = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
8698         if (Ovl != OR_Deleted) {
8699           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
8700               << DestType << ArgsRange;
8701           llvm_unreachable("Inconsistent overload resolution?");
8702           break;
8703         }
8704
8705         // If this is a defaulted or implicitly-declared function, then
8706         // it was implicitly deleted. Make it clear that the deletion was
8707         // implicit.
8708         if (S.isImplicitlyDeleted(Best->Function))
8709           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_special_init)
8710             << S.getSpecialMember(cast<CXXMethodDecl>(Best->Function))
8711             << DestType << ArgsRange;
8712         else
8713           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
8714               << DestType << ArgsRange;
8715
8716         S.NoteDeletedFunction(Best->Function);
8717         break;
8718       }
8719
8720       case OR_Success:
8721         llvm_unreachable("Conversion did not fail!");
8722     }
8723   }
8724   break;
8725
8726   case FK_DefaultInitOfConst:
8727     if (Entity.getKind() == InitializedEntity::EK_Member &&
8728         isa<CXXConstructorDecl>(S.CurContext)) {
8729       // This is implicit default-initialization of a const member in
8730       // a constructor. Complain that it needs to be explicitly
8731       // initialized.
8732       CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(S.CurContext);
8733       S.Diag(Kind.getLocation(), diag::err_uninitialized_member_in_ctor)
8734         << (Constructor->getInheritedConstructor() ? 2 :
8735             Constructor->isImplicit() ? 1 : 0)
8736         << S.Context.getTypeDeclType(Constructor->getParent())
8737         << /*const=*/1
8738         << Entity.getName();
8739       S.Diag(Entity.getDecl()->getLocation(), diag::note_previous_decl)
8740         << Entity.getName();
8741     } else {
8742       S.Diag(Kind.getLocation(), diag::err_default_init_const)
8743           << DestType << (bool)DestType->getAs<RecordType>();
8744     }
8745     break;
8746
8747   case FK_Incomplete:
8748     S.RequireCompleteType(Kind.getLocation(), FailedIncompleteType,
8749                           diag::err_init_incomplete_type);
8750     break;
8751
8752   case FK_ListInitializationFailed: {
8753     // Run the init list checker again to emit diagnostics.
8754     InitListExpr *InitList = cast<InitListExpr>(Args[0]);
8755     diagnoseListInit(S, Entity, InitList);
8756     break;
8757   }
8758
8759   case FK_PlaceholderType: {
8760     // FIXME: Already diagnosed!
8761     break;
8762   }
8763
8764   case FK_ExplicitConstructor: {
8765     S.Diag(Kind.getLocation(), diag::err_selected_explicit_constructor)
8766       << Args[0]->getSourceRange();
8767     OverloadCandidateSet::iterator Best;
8768     OverloadingResult Ovl
8769       = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
8770     (void)Ovl;
8771     assert(Ovl == OR_Success && "Inconsistent overload resolution");
8772     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
8773     S.Diag(CtorDecl->getLocation(),
8774            diag::note_explicit_ctor_deduction_guide_here) << false;
8775     break;
8776   }
8777   }
8778
8779   PrintInitLocationNote(S, Entity);
8780   return true;
8781 }
8782
8783 void InitializationSequence::dump(raw_ostream &OS) const {
8784   switch (SequenceKind) {
8785   case FailedSequence: {
8786     OS << "Failed sequence: ";
8787     switch (Failure) {
8788     case FK_TooManyInitsForReference:
8789       OS << "too many initializers for reference";
8790       break;
8791
8792     case FK_ParenthesizedListInitForReference:
8793       OS << "parenthesized list init for reference";
8794       break;
8795
8796     case FK_ArrayNeedsInitList:
8797       OS << "array requires initializer list";
8798       break;
8799
8800     case FK_AddressOfUnaddressableFunction:
8801       OS << "address of unaddressable function was taken";
8802       break;
8803
8804     case FK_ArrayNeedsInitListOrStringLiteral:
8805       OS << "array requires initializer list or string literal";
8806       break;
8807
8808     case FK_ArrayNeedsInitListOrWideStringLiteral:
8809       OS << "array requires initializer list or wide string literal";
8810       break;
8811
8812     case FK_NarrowStringIntoWideCharArray:
8813       OS << "narrow string into wide char array";
8814       break;
8815
8816     case FK_WideStringIntoCharArray:
8817       OS << "wide string into char array";
8818       break;
8819
8820     case FK_IncompatWideStringIntoWideChar:
8821       OS << "incompatible wide string into wide char array";
8822       break;
8823
8824     case FK_PlainStringIntoUTF8Char:
8825       OS << "plain string literal into char8_t array";
8826       break;
8827
8828     case FK_UTF8StringIntoPlainChar:
8829       OS << "u8 string literal into char array";
8830       break;
8831
8832     case FK_ArrayTypeMismatch:
8833       OS << "array type mismatch";
8834       break;
8835
8836     case FK_NonConstantArrayInit:
8837       OS << "non-constant array initializer";
8838       break;
8839
8840     case FK_AddressOfOverloadFailed:
8841       OS << "address of overloaded function failed";
8842       break;
8843
8844     case FK_ReferenceInitOverloadFailed:
8845       OS << "overload resolution for reference initialization failed";
8846       break;
8847
8848     case FK_NonConstLValueReferenceBindingToTemporary:
8849       OS << "non-const lvalue reference bound to temporary";
8850       break;
8851
8852     case FK_NonConstLValueReferenceBindingToBitfield:
8853       OS << "non-const lvalue reference bound to bit-field";
8854       break;
8855
8856     case FK_NonConstLValueReferenceBindingToVectorElement:
8857       OS << "non-const lvalue reference bound to vector element";
8858       break;
8859
8860     case FK_NonConstLValueReferenceBindingToUnrelated:
8861       OS << "non-const lvalue reference bound to unrelated type";
8862       break;
8863
8864     case FK_RValueReferenceBindingToLValue:
8865       OS << "rvalue reference bound to an lvalue";
8866       break;
8867
8868     case FK_ReferenceInitDropsQualifiers:
8869       OS << "reference initialization drops qualifiers";
8870       break;
8871
8872     case FK_ReferenceAddrspaceMismatchTemporary:
8873       OS << "reference with mismatching address space bound to temporary";
8874       break;
8875
8876     case FK_ReferenceInitFailed:
8877       OS << "reference initialization failed";
8878       break;
8879
8880     case FK_ConversionFailed:
8881       OS << "conversion failed";
8882       break;
8883
8884     case FK_ConversionFromPropertyFailed:
8885       OS << "conversion from property failed";
8886       break;
8887
8888     case FK_TooManyInitsForScalar:
8889       OS << "too many initializers for scalar";
8890       break;
8891
8892     case FK_ParenthesizedListInitForScalar:
8893       OS << "parenthesized list init for reference";
8894       break;
8895
8896     case FK_ReferenceBindingToInitList:
8897       OS << "referencing binding to initializer list";
8898       break;
8899
8900     case FK_InitListBadDestinationType:
8901       OS << "initializer list for non-aggregate, non-scalar type";
8902       break;
8903
8904     case FK_UserConversionOverloadFailed:
8905       OS << "overloading failed for user-defined conversion";
8906       break;
8907
8908     case FK_ConstructorOverloadFailed:
8909       OS << "constructor overloading failed";
8910       break;
8911
8912     case FK_DefaultInitOfConst:
8913       OS << "default initialization of a const variable";
8914       break;
8915
8916     case FK_Incomplete:
8917       OS << "initialization of incomplete type";
8918       break;
8919
8920     case FK_ListInitializationFailed:
8921       OS << "list initialization checker failure";
8922       break;
8923
8924     case FK_VariableLengthArrayHasInitializer:
8925       OS << "variable length array has an initializer";
8926       break;
8927
8928     case FK_PlaceholderType:
8929       OS << "initializer expression isn't contextually valid";
8930       break;
8931
8932     case FK_ListConstructorOverloadFailed:
8933       OS << "list constructor overloading failed";
8934       break;
8935
8936     case FK_ExplicitConstructor:
8937       OS << "list copy initialization chose explicit constructor";
8938       break;
8939     }
8940     OS << '\n';
8941     return;
8942   }
8943
8944   case DependentSequence:
8945     OS << "Dependent sequence\n";
8946     return;
8947
8948   case NormalSequence:
8949     OS << "Normal sequence: ";
8950     break;
8951   }
8952
8953   for (step_iterator S = step_begin(), SEnd = step_end(); S != SEnd; ++S) {
8954     if (S != step_begin()) {
8955       OS << " -> ";
8956     }
8957
8958     switch (S->Kind) {
8959     case SK_ResolveAddressOfOverloadedFunction:
8960       OS << "resolve address of overloaded function";
8961       break;
8962
8963     case SK_CastDerivedToBaseRValue:
8964       OS << "derived-to-base (rvalue)";
8965       break;
8966
8967     case SK_CastDerivedToBaseXValue:
8968       OS << "derived-to-base (xvalue)";
8969       break;
8970
8971     case SK_CastDerivedToBaseLValue:
8972       OS << "derived-to-base (lvalue)";
8973       break;
8974
8975     case SK_BindReference:
8976       OS << "bind reference to lvalue";
8977       break;
8978
8979     case SK_BindReferenceToTemporary:
8980       OS << "bind reference to a temporary";
8981       break;
8982
8983     case SK_FinalCopy:
8984       OS << "final copy in class direct-initialization";
8985       break;
8986
8987     case SK_ExtraneousCopyToTemporary:
8988       OS << "extraneous C++03 copy to temporary";
8989       break;
8990
8991     case SK_UserConversion:
8992       OS << "user-defined conversion via " << *S->Function.Function;
8993       break;
8994
8995     case SK_QualificationConversionRValue:
8996       OS << "qualification conversion (rvalue)";
8997       break;
8998
8999     case SK_QualificationConversionXValue:
9000       OS << "qualification conversion (xvalue)";
9001       break;
9002
9003     case SK_QualificationConversionLValue:
9004       OS << "qualification conversion (lvalue)";
9005       break;
9006
9007     case SK_AtomicConversion:
9008       OS << "non-atomic-to-atomic conversion";
9009       break;
9010
9011     case SK_ConversionSequence:
9012       OS << "implicit conversion sequence (";
9013       S->ICS->dump(); // FIXME: use OS
9014       OS << ")";
9015       break;
9016
9017     case SK_ConversionSequenceNoNarrowing:
9018       OS << "implicit conversion sequence with narrowing prohibited (";
9019       S->ICS->dump(); // FIXME: use OS
9020       OS << ")";
9021       break;
9022
9023     case SK_ListInitialization:
9024       OS << "list aggregate initialization";
9025       break;
9026
9027     case SK_UnwrapInitList:
9028       OS << "unwrap reference initializer list";
9029       break;
9030
9031     case SK_RewrapInitList:
9032       OS << "rewrap reference initializer list";
9033       break;
9034
9035     case SK_ConstructorInitialization:
9036       OS << "constructor initialization";
9037       break;
9038
9039     case SK_ConstructorInitializationFromList:
9040       OS << "list initialization via constructor";
9041       break;
9042
9043     case SK_ZeroInitialization:
9044       OS << "zero initialization";
9045       break;
9046
9047     case SK_CAssignment:
9048       OS << "C assignment";
9049       break;
9050
9051     case SK_StringInit:
9052       OS << "string initialization";
9053       break;
9054
9055     case SK_ObjCObjectConversion:
9056       OS << "Objective-C object conversion";
9057       break;
9058
9059     case SK_ArrayLoopIndex:
9060       OS << "indexing for array initialization loop";
9061       break;
9062
9063     case SK_ArrayLoopInit:
9064       OS << "array initialization loop";
9065       break;
9066
9067     case SK_ArrayInit:
9068       OS << "array initialization";
9069       break;
9070
9071     case SK_GNUArrayInit:
9072       OS << "array initialization (GNU extension)";
9073       break;
9074
9075     case SK_ParenthesizedArrayInit:
9076       OS << "parenthesized array initialization";
9077       break;
9078
9079     case SK_PassByIndirectCopyRestore:
9080       OS << "pass by indirect copy and restore";
9081       break;
9082
9083     case SK_PassByIndirectRestore:
9084       OS << "pass by indirect restore";
9085       break;
9086
9087     case SK_ProduceObjCObject:
9088       OS << "Objective-C object retension";
9089       break;
9090
9091     case SK_StdInitializerList:
9092       OS << "std::initializer_list from initializer list";
9093       break;
9094
9095     case SK_StdInitializerListConstructorCall:
9096       OS << "list initialization from std::initializer_list";
9097       break;
9098
9099     case SK_OCLSamplerInit:
9100       OS << "OpenCL sampler_t from integer constant";
9101       break;
9102
9103     case SK_OCLZeroOpaqueType:
9104       OS << "OpenCL opaque type from zero";
9105       break;
9106     }
9107
9108     OS << " [" << S->Type.getAsString() << ']';
9109   }
9110
9111   OS << '\n';
9112 }
9113
9114 void InitializationSequence::dump() const {
9115   dump(llvm::errs());
9116 }
9117
9118 static bool NarrowingErrs(const LangOptions &L) {
9119   return L.CPlusPlus11 &&
9120          (!L.MicrosoftExt || L.isCompatibleWithMSVC(LangOptions::MSVC2015));
9121 }
9122
9123 static void DiagnoseNarrowingInInitList(Sema &S,
9124                                         const ImplicitConversionSequence &ICS,
9125                                         QualType PreNarrowingType,
9126                                         QualType EntityType,
9127                                         const Expr *PostInit) {
9128   const StandardConversionSequence *SCS = nullptr;
9129   switch (ICS.getKind()) {
9130   case ImplicitConversionSequence::StandardConversion:
9131     SCS = &ICS.Standard;
9132     break;
9133   case ImplicitConversionSequence::UserDefinedConversion:
9134     SCS = &ICS.UserDefined.After;
9135     break;
9136   case ImplicitConversionSequence::AmbiguousConversion:
9137   case ImplicitConversionSequence::EllipsisConversion:
9138   case ImplicitConversionSequence::BadConversion:
9139     return;
9140   }
9141
9142   // C++11 [dcl.init.list]p7: Check whether this is a narrowing conversion.
9143   APValue ConstantValue;
9144   QualType ConstantType;
9145   switch (SCS->getNarrowingKind(S.Context, PostInit, ConstantValue,
9146                                 ConstantType)) {
9147   case NK_Not_Narrowing:
9148   case NK_Dependent_Narrowing:
9149     // No narrowing occurred.
9150     return;
9151
9152   case NK_Type_Narrowing:
9153     // This was a floating-to-integer conversion, which is always considered a
9154     // narrowing conversion even if the value is a constant and can be
9155     // represented exactly as an integer.
9156     S.Diag(PostInit->getBeginLoc(), NarrowingErrs(S.getLangOpts())
9157                                         ? diag::ext_init_list_type_narrowing
9158                                         : diag::warn_init_list_type_narrowing)
9159         << PostInit->getSourceRange()
9160         << PreNarrowingType.getLocalUnqualifiedType()
9161         << EntityType.getLocalUnqualifiedType();
9162     break;
9163
9164   case NK_Constant_Narrowing:
9165     // A constant value was narrowed.
9166     S.Diag(PostInit->getBeginLoc(),
9167            NarrowingErrs(S.getLangOpts())
9168                ? diag::ext_init_list_constant_narrowing
9169                : diag::warn_init_list_constant_narrowing)
9170         << PostInit->getSourceRange()
9171         << ConstantValue.getAsString(S.getASTContext(), ConstantType)
9172         << EntityType.getLocalUnqualifiedType();
9173     break;
9174
9175   case NK_Variable_Narrowing:
9176     // A variable's value may have been narrowed.
9177     S.Diag(PostInit->getBeginLoc(),
9178            NarrowingErrs(S.getLangOpts())
9179                ? diag::ext_init_list_variable_narrowing
9180                : diag::warn_init_list_variable_narrowing)
9181         << PostInit->getSourceRange()
9182         << PreNarrowingType.getLocalUnqualifiedType()
9183         << EntityType.getLocalUnqualifiedType();
9184     break;
9185   }
9186
9187   SmallString<128> StaticCast;
9188   llvm::raw_svector_ostream OS(StaticCast);
9189   OS << "static_cast<";
9190   if (const TypedefType *TT = EntityType->getAs<TypedefType>()) {
9191     // It's important to use the typedef's name if there is one so that the
9192     // fixit doesn't break code using types like int64_t.
9193     //
9194     // FIXME: This will break if the typedef requires qualification.  But
9195     // getQualifiedNameAsString() includes non-machine-parsable components.
9196     OS << *TT->getDecl();
9197   } else if (const BuiltinType *BT = EntityType->getAs<BuiltinType>())
9198     OS << BT->getName(S.getLangOpts());
9199   else {
9200     // Oops, we didn't find the actual type of the variable.  Don't emit a fixit
9201     // with a broken cast.
9202     return;
9203   }
9204   OS << ">(";
9205   S.Diag(PostInit->getBeginLoc(), diag::note_init_list_narrowing_silence)
9206       << PostInit->getSourceRange()
9207       << FixItHint::CreateInsertion(PostInit->getBeginLoc(), OS.str())
9208       << FixItHint::CreateInsertion(
9209              S.getLocForEndOfToken(PostInit->getEndLoc()), ")");
9210 }
9211
9212 //===----------------------------------------------------------------------===//
9213 // Initialization helper functions
9214 //===----------------------------------------------------------------------===//
9215 bool
9216 Sema::CanPerformCopyInitialization(const InitializedEntity &Entity,
9217                                    ExprResult Init) {
9218   if (Init.isInvalid())
9219     return false;
9220
9221   Expr *InitE = Init.get();
9222   assert(InitE && "No initialization expression");
9223
9224   InitializationKind Kind =
9225       InitializationKind::CreateCopy(InitE->getBeginLoc(), SourceLocation());
9226   InitializationSequence Seq(*this, Entity, Kind, InitE);
9227   return !Seq.Failed();
9228 }
9229
9230 ExprResult
9231 Sema::PerformCopyInitialization(const InitializedEntity &Entity,
9232                                 SourceLocation EqualLoc,
9233                                 ExprResult Init,
9234                                 bool TopLevelOfInitList,
9235                                 bool AllowExplicit) {
9236   if (Init.isInvalid())
9237     return ExprError();
9238
9239   Expr *InitE = Init.get();
9240   assert(InitE && "No initialization expression?");
9241
9242   if (EqualLoc.isInvalid())
9243     EqualLoc = InitE->getBeginLoc();
9244
9245   InitializationKind Kind = InitializationKind::CreateCopy(
9246       InitE->getBeginLoc(), EqualLoc, AllowExplicit);
9247   InitializationSequence Seq(*this, Entity, Kind, InitE, TopLevelOfInitList);
9248
9249   // Prevent infinite recursion when performing parameter copy-initialization.
9250   const bool ShouldTrackCopy =
9251       Entity.isParameterKind() && Seq.isConstructorInitialization();
9252   if (ShouldTrackCopy) {
9253     if (llvm::find(CurrentParameterCopyTypes, Entity.getType()) !=
9254         CurrentParameterCopyTypes.end()) {
9255       Seq.SetOverloadFailure(
9256           InitializationSequence::FK_ConstructorOverloadFailed,
9257           OR_No_Viable_Function);
9258
9259       // Try to give a meaningful diagnostic note for the problematic
9260       // constructor.
9261       const auto LastStep = Seq.step_end() - 1;
9262       assert(LastStep->Kind ==
9263              InitializationSequence::SK_ConstructorInitialization);
9264       const FunctionDecl *Function = LastStep->Function.Function;
9265       auto Candidate =
9266           llvm::find_if(Seq.getFailedCandidateSet(),
9267                         [Function](const OverloadCandidate &Candidate) -> bool {
9268                           return Candidate.Viable &&
9269                                  Candidate.Function == Function &&
9270                                  Candidate.Conversions.size() > 0;
9271                         });
9272       if (Candidate != Seq.getFailedCandidateSet().end() &&
9273           Function->getNumParams() > 0) {
9274         Candidate->Viable = false;
9275         Candidate->FailureKind = ovl_fail_bad_conversion;
9276         Candidate->Conversions[0].setBad(BadConversionSequence::no_conversion,
9277                                          InitE,
9278                                          Function->getParamDecl(0)->getType());
9279       }
9280     }
9281     CurrentParameterCopyTypes.push_back(Entity.getType());
9282   }
9283
9284   ExprResult Result = Seq.Perform(*this, Entity, Kind, InitE);
9285
9286   if (ShouldTrackCopy)
9287     CurrentParameterCopyTypes.pop_back();
9288
9289   return Result;
9290 }
9291
9292 /// Determine whether RD is, or is derived from, a specialization of CTD.
9293 static bool isOrIsDerivedFromSpecializationOf(CXXRecordDecl *RD,
9294                                               ClassTemplateDecl *CTD) {
9295   auto NotSpecialization = [&] (const CXXRecordDecl *Candidate) {
9296     auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(Candidate);
9297     return !CTSD || !declaresSameEntity(CTSD->getSpecializedTemplate(), CTD);
9298   };
9299   return !(NotSpecialization(RD) && RD->forallBases(NotSpecialization));
9300 }
9301
9302 QualType Sema::DeduceTemplateSpecializationFromInitializer(
9303     TypeSourceInfo *TSInfo, const InitializedEntity &Entity,
9304     const InitializationKind &Kind, MultiExprArg Inits) {
9305   auto *DeducedTST = dyn_cast<DeducedTemplateSpecializationType>(
9306       TSInfo->getType()->getContainedDeducedType());
9307   assert(DeducedTST && "not a deduced template specialization type");
9308
9309   auto TemplateName = DeducedTST->getTemplateName();
9310   if (TemplateName.isDependent())
9311     return Context.DependentTy;
9312
9313   // We can only perform deduction for class templates.
9314   auto *Template =
9315       dyn_cast_or_null<ClassTemplateDecl>(TemplateName.getAsTemplateDecl());
9316   if (!Template) {
9317     Diag(Kind.getLocation(),
9318          diag::err_deduced_non_class_template_specialization_type)
9319       << (int)getTemplateNameKindForDiagnostics(TemplateName) << TemplateName;
9320     if (auto *TD = TemplateName.getAsTemplateDecl())
9321       Diag(TD->getLocation(), diag::note_template_decl_here);
9322     return QualType();
9323   }
9324
9325   // Can't deduce from dependent arguments.
9326   if (Expr::hasAnyTypeDependentArguments(Inits)) {
9327     Diag(TSInfo->getTypeLoc().getBeginLoc(),
9328          diag::warn_cxx14_compat_class_template_argument_deduction)
9329         << TSInfo->getTypeLoc().getSourceRange() << 0;
9330     return Context.DependentTy;
9331   }
9332
9333   // FIXME: Perform "exact type" matching first, per CWG discussion?
9334   //        Or implement this via an implied 'T(T) -> T' deduction guide?
9335
9336   // FIXME: Do we need/want a std::initializer_list<T> special case?
9337
9338   // Look up deduction guides, including those synthesized from constructors.
9339   //
9340   // C++1z [over.match.class.deduct]p1:
9341   //   A set of functions and function templates is formed comprising:
9342   //   - For each constructor of the class template designated by the
9343   //     template-name, a function template [...]
9344   //  - For each deduction-guide, a function or function template [...]
9345   DeclarationNameInfo NameInfo(
9346       Context.DeclarationNames.getCXXDeductionGuideName(Template),
9347       TSInfo->getTypeLoc().getEndLoc());
9348   LookupResult Guides(*this, NameInfo, LookupOrdinaryName);
9349   LookupQualifiedName(Guides, Template->getDeclContext());
9350
9351   // FIXME: Do not diagnose inaccessible deduction guides. The standard isn't
9352   // clear on this, but they're not found by name so access does not apply.
9353   Guides.suppressDiagnostics();
9354
9355   // Figure out if this is list-initialization.
9356   InitListExpr *ListInit =
9357       (Inits.size() == 1 && Kind.getKind() != InitializationKind::IK_Direct)
9358           ? dyn_cast<InitListExpr>(Inits[0])
9359           : nullptr;
9360
9361   // C++1z [over.match.class.deduct]p1:
9362   //   Initialization and overload resolution are performed as described in
9363   //   [dcl.init] and [over.match.ctor], [over.match.copy], or [over.match.list]
9364   //   (as appropriate for the type of initialization performed) for an object
9365   //   of a hypothetical class type, where the selected functions and function
9366   //   templates are considered to be the constructors of that class type
9367   //
9368   // Since we know we're initializing a class type of a type unrelated to that
9369   // of the initializer, this reduces to something fairly reasonable.
9370   OverloadCandidateSet Candidates(Kind.getLocation(),
9371                                   OverloadCandidateSet::CSK_Normal);
9372   OverloadCandidateSet::iterator Best;
9373
9374   bool HasAnyDeductionGuide = false;
9375   bool AllowExplicit = !Kind.isCopyInit() || ListInit;
9376
9377   auto tryToResolveOverload =
9378       [&](bool OnlyListConstructors) -> OverloadingResult {
9379     Candidates.clear(OverloadCandidateSet::CSK_Normal);
9380     HasAnyDeductionGuide = false;
9381
9382     for (auto I = Guides.begin(), E = Guides.end(); I != E; ++I) {
9383       NamedDecl *D = (*I)->getUnderlyingDecl();
9384       if (D->isInvalidDecl())
9385         continue;
9386
9387       auto *TD = dyn_cast<FunctionTemplateDecl>(D);
9388       auto *GD = dyn_cast_or_null<CXXDeductionGuideDecl>(
9389           TD ? TD->getTemplatedDecl() : dyn_cast<FunctionDecl>(D));
9390       if (!GD)
9391         continue;
9392
9393       if (!GD->isImplicit())
9394         HasAnyDeductionGuide = true;
9395
9396       // C++ [over.match.ctor]p1: (non-list copy-initialization from non-class)
9397       //   For copy-initialization, the candidate functions are all the
9398       //   converting constructors (12.3.1) of that class.
9399       // C++ [over.match.copy]p1: (non-list copy-initialization from class)
9400       //   The converting constructors of T are candidate functions.
9401       if (!AllowExplicit) {
9402         // Only consider converting constructors.
9403         if (GD->isExplicit())
9404           continue;
9405
9406         // When looking for a converting constructor, deduction guides that
9407         // could never be called with one argument are not interesting to
9408         // check or note.
9409         if (GD->getMinRequiredArguments() > 1 ||
9410             (GD->getNumParams() == 0 && !GD->isVariadic()))
9411           continue;
9412       }
9413
9414       // C++ [over.match.list]p1.1: (first phase list initialization)
9415       //   Initially, the candidate functions are the initializer-list
9416       //   constructors of the class T
9417       if (OnlyListConstructors && !isInitListConstructor(GD))
9418         continue;
9419
9420       // C++ [over.match.list]p1.2: (second phase list initialization)
9421       //   the candidate functions are all the constructors of the class T
9422       // C++ [over.match.ctor]p1: (all other cases)
9423       //   the candidate functions are all the constructors of the class of
9424       //   the object being initialized
9425
9426       // C++ [over.best.ics]p4:
9427       //   When [...] the constructor [...] is a candidate by
9428       //    - [over.match.copy] (in all cases)
9429       // FIXME: The "second phase of [over.match.list] case can also
9430       // theoretically happen here, but it's not clear whether we can
9431       // ever have a parameter of the right type.
9432       bool SuppressUserConversions = Kind.isCopyInit();
9433
9434       if (TD)
9435         AddTemplateOverloadCandidate(TD, I.getPair(), /*ExplicitArgs*/ nullptr,
9436                                      Inits, Candidates, SuppressUserConversions,
9437                                      /*PartialOverloading*/ false,
9438                                      AllowExplicit);
9439       else
9440         AddOverloadCandidate(GD, I.getPair(), Inits, Candidates,
9441                              SuppressUserConversions,
9442                              /*PartialOverloading*/ false, AllowExplicit);
9443     }
9444     return Candidates.BestViableFunction(*this, Kind.getLocation(), Best);
9445   };
9446
9447   OverloadingResult Result = OR_No_Viable_Function;
9448
9449   // C++11 [over.match.list]p1, per DR1467: for list-initialization, first
9450   // try initializer-list constructors.
9451   if (ListInit) {
9452     bool TryListConstructors = true;
9453
9454     // Try list constructors unless the list is empty and the class has one or
9455     // more default constructors, in which case those constructors win.
9456     if (!ListInit->getNumInits()) {
9457       for (NamedDecl *D : Guides) {
9458         auto *FD = dyn_cast<FunctionDecl>(D->getUnderlyingDecl());
9459         if (FD && FD->getMinRequiredArguments() == 0) {
9460           TryListConstructors = false;
9461           break;
9462         }
9463       }
9464     } else if (ListInit->getNumInits() == 1) {
9465       // C++ [over.match.class.deduct]:
9466       //   As an exception, the first phase in [over.match.list] (considering
9467       //   initializer-list constructors) is omitted if the initializer list
9468       //   consists of a single expression of type cv U, where U is a
9469       //   specialization of C or a class derived from a specialization of C.
9470       Expr *E = ListInit->getInit(0);
9471       auto *RD = E->getType()->getAsCXXRecordDecl();
9472       if (!isa<InitListExpr>(E) && RD &&
9473           isCompleteType(Kind.getLocation(), E->getType()) &&
9474           isOrIsDerivedFromSpecializationOf(RD, Template))
9475         TryListConstructors = false;
9476     }
9477
9478     if (TryListConstructors)
9479       Result = tryToResolveOverload(/*OnlyListConstructor*/true);
9480     // Then unwrap the initializer list and try again considering all
9481     // constructors.
9482     Inits = MultiExprArg(ListInit->getInits(), ListInit->getNumInits());
9483   }
9484
9485   // If list-initialization fails, or if we're doing any other kind of
9486   // initialization, we (eventually) consider constructors.
9487   if (Result == OR_No_Viable_Function)
9488     Result = tryToResolveOverload(/*OnlyListConstructor*/false);
9489
9490   switch (Result) {
9491   case OR_Ambiguous:
9492     // FIXME: For list-initialization candidates, it'd usually be better to
9493     // list why they were not viable when given the initializer list itself as
9494     // an argument.
9495     Candidates.NoteCandidates(
9496         PartialDiagnosticAt(
9497             Kind.getLocation(),
9498             PDiag(diag::err_deduced_class_template_ctor_ambiguous)
9499                 << TemplateName),
9500         *this, OCD_ViableCandidates, Inits);
9501     return QualType();
9502
9503   case OR_No_Viable_Function: {
9504     CXXRecordDecl *Primary =
9505         cast<ClassTemplateDecl>(Template)->getTemplatedDecl();
9506     bool Complete =
9507         isCompleteType(Kind.getLocation(), Context.getTypeDeclType(Primary));
9508     Candidates.NoteCandidates(
9509         PartialDiagnosticAt(
9510             Kind.getLocation(),
9511             PDiag(Complete ? diag::err_deduced_class_template_ctor_no_viable
9512                            : diag::err_deduced_class_template_incomplete)
9513                 << TemplateName << !Guides.empty()),
9514         *this, OCD_AllCandidates, Inits);
9515     return QualType();
9516   }
9517
9518   case OR_Deleted: {
9519     Diag(Kind.getLocation(), diag::err_deduced_class_template_deleted)
9520       << TemplateName;
9521     NoteDeletedFunction(Best->Function);
9522     return QualType();
9523   }
9524
9525   case OR_Success:
9526     // C++ [over.match.list]p1:
9527     //   In copy-list-initialization, if an explicit constructor is chosen, the
9528     //   initialization is ill-formed.
9529     if (Kind.isCopyInit() && ListInit &&
9530         cast<CXXDeductionGuideDecl>(Best->Function)->isExplicit()) {
9531       bool IsDeductionGuide = !Best->Function->isImplicit();
9532       Diag(Kind.getLocation(), diag::err_deduced_class_template_explicit)
9533           << TemplateName << IsDeductionGuide;
9534       Diag(Best->Function->getLocation(),
9535            diag::note_explicit_ctor_deduction_guide_here)
9536           << IsDeductionGuide;
9537       return QualType();
9538     }
9539
9540     // Make sure we didn't select an unusable deduction guide, and mark it
9541     // as referenced.
9542     DiagnoseUseOfDecl(Best->Function, Kind.getLocation());
9543     MarkFunctionReferenced(Kind.getLocation(), Best->Function);
9544     break;
9545   }
9546
9547   // C++ [dcl.type.class.deduct]p1:
9548   //  The placeholder is replaced by the return type of the function selected
9549   //  by overload resolution for class template deduction.
9550   QualType DeducedType =
9551       SubstAutoType(TSInfo->getType(), Best->Function->getReturnType());
9552   Diag(TSInfo->getTypeLoc().getBeginLoc(),
9553        diag::warn_cxx14_compat_class_template_argument_deduction)
9554       << TSInfo->getTypeLoc().getSourceRange() << 1 << DeducedType;
9555
9556   // Warn if CTAD was used on a type that does not have any user-defined
9557   // deduction guides.
9558   if (!HasAnyDeductionGuide) {
9559     Diag(TSInfo->getTypeLoc().getBeginLoc(),
9560          diag::warn_ctad_maybe_unsupported)
9561         << TemplateName;
9562     Diag(Template->getLocation(), diag::note_suppress_ctad_maybe_unsupported);
9563   }
9564
9565   return DeducedType;
9566 }