contrib/llvm/tools/clang/lib/Sema/SemaInit.cpp

   1 //===--- SemaInit.cpp - Semantic Analysis for Initializers ----------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements semantic analysis for initializers.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "clang/AST/ASTContext.h"
  15 #include "clang/AST/DeclObjC.h"
  16 #include "clang/AST/ExprCXX.h"
  17 #include "clang/AST/ExprObjC.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 /// \brief 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_Other
  53 };
  54
  55 /// \brief Check whether the array of type AT can be initialized by the Init
  56 /// expression by means of string initialization. Returns SIF_None if so,
  57 /// otherwise returns a StringInitFailureKind that describes why the
  58 /// initialization would not work.
  59 static StringInitFailureKind IsStringInit(Expr *Init, const ArrayType *AT,
  60                                           ASTContext &Context) {
  61   if (!isa<ConstantArrayType>(AT) && !isa<IncompleteArrayType>(AT))
  62     return SIF_Other;
  63
  64   // See if this is a string literal or @encode.
  65   Init = Init->IgnoreParens();
  66
  67   // Handle @encode, which is a narrow string.
  68   if (isa<ObjCEncodeExpr>(Init) && AT->getElementType()->isCharType())
  69     return SIF_None;
  70
  71   // Otherwise we can only handle string literals.
  72   StringLiteral *SL = dyn_cast<StringLiteral>(Init);
  73   if (!SL)
  74     return SIF_Other;
  75
  76   const QualType ElemTy =
  77       Context.getCanonicalType(AT->getElementType()).getUnqualifiedType();
  78
  79   switch (SL->getKind()) {
  80   case StringLiteral::Ascii:
  81   case StringLiteral::UTF8:
  82     // char array can be initialized with a narrow string.
  83     // Only allow char x[] = "foo";  not char x[] = L"foo";
  84     if (ElemTy->isCharType())
  85       return SIF_None;
  86     if (IsWideCharCompatible(ElemTy, Context))
  87       return SIF_NarrowStringIntoWideChar;
  88     return SIF_Other;
  89   // C99 6.7.8p15 (with correction from DR343), or C11 6.7.9p15:
  90   // "An array with element type compatible with a qualified or unqualified
  91   // version of wchar_t, char16_t, or char32_t may be initialized by a wide
  92   // string literal with the corresponding encoding prefix (L, u, or U,
  93   // respectively), optionally enclosed in braces.
  94   case StringLiteral::UTF16:
  95     if (Context.typesAreCompatible(Context.Char16Ty, ElemTy))
  96       return SIF_None;
  97     if (ElemTy->isCharType())
  98       return SIF_WideStringIntoChar;
  99     if (IsWideCharCompatible(ElemTy, Context))
 100       return SIF_IncompatWideStringIntoWideChar;
 101     return SIF_Other;
 102   case StringLiteral::UTF32:
 103     if (Context.typesAreCompatible(Context.Char32Ty, ElemTy))
 104       return SIF_None;
 105     if (ElemTy->isCharType())
 106       return SIF_WideStringIntoChar;
 107     if (IsWideCharCompatible(ElemTy, Context))
 108       return SIF_IncompatWideStringIntoWideChar;
 109     return SIF_Other;
 110   case StringLiteral::Wide:
 111     if (Context.typesAreCompatible(Context.getWideCharType(), ElemTy))
 112       return SIF_None;
 113     if (ElemTy->isCharType())
 114       return SIF_WideStringIntoChar;
 115     if (IsWideCharCompatible(ElemTy, Context))
 116       return SIF_IncompatWideStringIntoWideChar;
 117     return SIF_Other;
 118   }
 119
 120   llvm_unreachable("missed a StringLiteral kind?");
 121 }
 122
 123 static StringInitFailureKind IsStringInit(Expr *init, QualType declType,
 124                                           ASTContext &Context) {
 125   const ArrayType *arrayType = Context.getAsArrayType(declType);
 126   if (!arrayType)
 127     return SIF_Other;
 128   return IsStringInit(init, arrayType, Context);
 129 }
 130
 131 /// Update the type of a string literal, including any surrounding parentheses,
 132 /// to match the type of the object which it is initializing.
 133 static void updateStringLiteralType(Expr *E, QualType Ty) {
 134   while (true) {
 135     E->setType(Ty);
 136     if (isa<StringLiteral>(E) || isa<ObjCEncodeExpr>(E))
 137       break;
 138     else if (ParenExpr *PE = dyn_cast<ParenExpr>(E))
 139       E = PE->getSubExpr();
 140     else if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E))
 141       E = UO->getSubExpr();
 142     else if (GenericSelectionExpr *GSE = dyn_cast<GenericSelectionExpr>(E))
 143       E = GSE->getResultExpr();
 144     else
 145       llvm_unreachable("unexpected expr in string literal init");
 146   }
 147 }
 148
 149 static void CheckStringInit(Expr *Str, QualType &DeclT, const ArrayType *AT,
 150                             Sema &S) {
 151   // Get the length of the string as parsed.
 152   auto *ConstantArrayTy =
 153       cast<ConstantArrayType>(Str->getType()->getAsArrayTypeUnsafe());
 154   uint64_t StrLength = ConstantArrayTy->getSize().getZExtValue();
 155
 156   if (const IncompleteArrayType *IAT = dyn_cast<IncompleteArrayType>(AT)) {
 157     // C99 6.7.8p14. We have an array of character type with unknown size
 158     // being initialized to a string literal.
 159     llvm::APInt ConstVal(32, StrLength);
 160     // Return a new array type (C99 6.7.8p22).
 161     DeclT = S.Context.getConstantArrayType(IAT->getElementType(),
 162                                            ConstVal,
 163                                            ArrayType::Normal, 0);
 164     updateStringLiteralType(Str, DeclT);
 165     return;
 166   }
 167
 168   const ConstantArrayType *CAT = cast<ConstantArrayType>(AT);
 169
 170   // We have an array of character type with known size.  However,
 171   // the size may be smaller or larger than the string we are initializing.
 172   // FIXME: Avoid truncation for 64-bit length strings.
 173   if (S.getLangOpts().CPlusPlus) {
 174     if (StringLiteral *SL = dyn_cast<StringLiteral>(Str->IgnoreParens())) {
 175       // For Pascal strings it's OK to strip off the terminating null character,
 176       // so the example below is valid:
 177       //
 178       // unsigned char a[2] = "\pa";
 179       if (SL->isPascal())
 180         StrLength--;
 181     }
 182
 183     // [dcl.init.string]p2
 184     if (StrLength > CAT->getSize().getZExtValue())
 185       S.Diag(Str->getLocStart(),
 186              diag::err_initializer_string_for_char_array_too_long)
 187         << Str->getSourceRange();
 188   } else {
 189     // C99 6.7.8p14.
 190     if (StrLength-1 > CAT->getSize().getZExtValue())
 191       S.Diag(Str->getLocStart(),
 192              diag::ext_initializer_string_for_char_array_too_long)
 193         << Str->getSourceRange();
 194   }
 195
 196   // Set the type to the actual size that we are initializing.  If we have
 197   // something like:
 198   //   char x[1] = "foo";
 199   // then this will set the string literal's type to char[1].
 200   updateStringLiteralType(Str, DeclT);
 201 }
 202
 203 //===----------------------------------------------------------------------===//
 204 // Semantic checking for initializer lists.
 205 //===----------------------------------------------------------------------===//
 206
 207 namespace {
 208
 209 /// @brief Semantic checking for initializer lists.
 210 ///
 211 /// The InitListChecker class contains a set of routines that each
 212 /// handle the initialization of a certain kind of entity, e.g.,
 213 /// arrays, vectors, struct/union types, scalars, etc. The
 214 /// InitListChecker itself performs a recursive walk of the subobject
 215 /// structure of the type to be initialized, while stepping through
 216 /// the initializer list one element at a time. The IList and Index
 217 /// parameters to each of the Check* routines contain the active
 218 /// (syntactic) initializer list and the index into that initializer
 219 /// list that represents the current initializer. Each routine is
 220 /// responsible for moving that Index forward as it consumes elements.
 221 ///
 222 /// Each Check* routine also has a StructuredList/StructuredIndex
 223 /// arguments, which contains the current "structured" (semantic)
 224 /// initializer list and the index into that initializer list where we
 225 /// are copying initializers as we map them over to the semantic
 226 /// list. Once we have completed our recursive walk of the subobject
 227 /// structure, we will have constructed a full semantic initializer
 228 /// list.
 229 ///
 230 /// C99 designators cause changes in the initializer list traversal,
 231 /// because they make the initialization "jump" into a specific
 232 /// subobject and then continue the initialization from that
 233 /// point. CheckDesignatedInitializer() recursively steps into the
 234 /// designated subobject and manages backing out the recursion to
 235 /// initialize the subobjects after the one designated.
 236 class InitListChecker {
 237   Sema &SemaRef;
 238   bool hadError;
 239   bool VerifyOnly; // no diagnostics, no structure building
 240   bool TreatUnavailableAsInvalid; // Used only in VerifyOnly mode.
 241   llvm::DenseMap<InitListExpr *, InitListExpr *> SyntacticToSemantic;
 242   InitListExpr *FullyStructuredList;
 243
 244   void CheckImplicitInitList(const InitializedEntity &Entity,
 245                              InitListExpr *ParentIList, QualType T,
 246                              unsigned &Index, InitListExpr *StructuredList,
 247                              unsigned &StructuredIndex);
 248   void CheckExplicitInitList(const InitializedEntity &Entity,
 249                              InitListExpr *IList, QualType &T,
 250                              InitListExpr *StructuredList,
 251                              bool TopLevelObject = false);
 252   void CheckListElementTypes(const InitializedEntity &Entity,
 253                              InitListExpr *IList, QualType &DeclType,
 254                              bool SubobjectIsDesignatorContext,
 255                              unsigned &Index,
 256                              InitListExpr *StructuredList,
 257                              unsigned &StructuredIndex,
 258                              bool TopLevelObject = false);
 259   void CheckSubElementType(const InitializedEntity &Entity,
 260                            InitListExpr *IList, QualType ElemType,
 261                            unsigned &Index,
 262                            InitListExpr *StructuredList,
 263                            unsigned &StructuredIndex);
 264   void CheckComplexType(const InitializedEntity &Entity,
 265                         InitListExpr *IList, QualType DeclType,
 266                         unsigned &Index,
 267                         InitListExpr *StructuredList,
 268                         unsigned &StructuredIndex);
 269   void CheckScalarType(const InitializedEntity &Entity,
 270                        InitListExpr *IList, QualType DeclType,
 271                        unsigned &Index,
 272                        InitListExpr *StructuredList,
 273                        unsigned &StructuredIndex);
 274   void CheckReferenceType(const InitializedEntity &Entity,
 275                           InitListExpr *IList, QualType DeclType,
 276                           unsigned &Index,
 277                           InitListExpr *StructuredList,
 278                           unsigned &StructuredIndex);
 279   void CheckVectorType(const InitializedEntity &Entity,
 280                        InitListExpr *IList, QualType DeclType, unsigned &Index,
 281                        InitListExpr *StructuredList,
 282                        unsigned &StructuredIndex);
 283   void CheckStructUnionTypes(const InitializedEntity &Entity,
 284                              InitListExpr *IList, QualType DeclType,
 285                              CXXRecordDecl::base_class_range Bases,
 286                              RecordDecl::field_iterator Field,
 287                              bool SubobjectIsDesignatorContext, unsigned &Index,
 288                              InitListExpr *StructuredList,
 289                              unsigned &StructuredIndex,
 290                              bool TopLevelObject = false);
 291   void CheckArrayType(const InitializedEntity &Entity,
 292                       InitListExpr *IList, QualType &DeclType,
 293                       llvm::APSInt elementIndex,
 294                       bool SubobjectIsDesignatorContext, unsigned &Index,
 295                       InitListExpr *StructuredList,
 296                       unsigned &StructuredIndex);
 297   bool CheckDesignatedInitializer(const InitializedEntity &Entity,
 298                                   InitListExpr *IList, DesignatedInitExpr *DIE,
 299                                   unsigned DesigIdx,
 300                                   QualType &CurrentObjectType,
 301                                   RecordDecl::field_iterator *NextField,
 302                                   llvm::APSInt *NextElementIndex,
 303                                   unsigned &Index,
 304                                   InitListExpr *StructuredList,
 305                                   unsigned &StructuredIndex,
 306                                   bool FinishSubobjectInit,
 307                                   bool TopLevelObject);
 308   InitListExpr *getStructuredSubobjectInit(InitListExpr *IList, unsigned Index,
 309                                            QualType CurrentObjectType,
 310                                            InitListExpr *StructuredList,
 311                                            unsigned StructuredIndex,
 312                                            SourceRange InitRange,
 313                                            bool IsFullyOverwritten = false);
 314   void UpdateStructuredListElement(InitListExpr *StructuredList,
 315                                    unsigned &StructuredIndex,
 316                                    Expr *expr);
 317   int numArrayElements(QualType DeclType);
 318   int numStructUnionElements(QualType DeclType);
 319
 320   static ExprResult PerformEmptyInit(Sema &SemaRef,
 321                                      SourceLocation Loc,
 322                                      const InitializedEntity &Entity,
 323                                      bool VerifyOnly,
 324                                      bool TreatUnavailableAsInvalid);
 325
 326   // Explanation on the "FillWithNoInit" mode:
 327   //
 328   // Assume we have the following definitions (Case#1):
 329   // struct P { char x[6][6]; } xp = { .x[1] = "bar" };
 330   // struct PP { struct P lp; } l = { .lp = xp, .lp.x[1][2] = 'f' };
 331   //
 332   // l.lp.x[1][0..1] should not be filled with implicit initializers because the
 333   // "base" initializer "xp" will provide values for them; l.lp.x[1] will be "baf".
 334   //
 335   // But if we have (Case#2):
 336   // struct PP l = { .lp = xp, .lp.x[1] = { [2] = 'f' } };
 337   //
 338   // l.lp.x[1][0..1] are implicitly initialized and do not use values from the
 339   // "base" initializer; l.lp.x[1] will be "\0\0f\0\0\0".
 340   //
 341   // To distinguish Case#1 from Case#2, and also to avoid leaving many "holes"
 342   // in the InitListExpr, the "holes" in Case#1 are filled not with empty
 343   // initializers but with special "NoInitExpr" place holders, which tells the
 344   // CodeGen not to generate any initializers for these parts.
 345   void FillInEmptyInitForBase(unsigned Init, const CXXBaseSpecifier &Base,
 346                               const InitializedEntity &ParentEntity,
 347                               InitListExpr *ILE, bool &RequiresSecondPass,
 348                               bool FillWithNoInit);
 349   void FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
 350                                const InitializedEntity &ParentEntity,
 351                                InitListExpr *ILE, bool &RequiresSecondPass,
 352                                bool FillWithNoInit = false);
 353   void FillInEmptyInitializations(const InitializedEntity &Entity,
 354                                   InitListExpr *ILE, bool &RequiresSecondPass,
 355                                   bool FillWithNoInit = false);
 356   bool CheckFlexibleArrayInit(const InitializedEntity &Entity,
 357                               Expr *InitExpr, FieldDecl *Field,
 358                               bool TopLevelObject);
 359   void CheckEmptyInitializable(const InitializedEntity &Entity,
 360                                SourceLocation Loc);
 361
 362 public:
 363   InitListChecker(Sema &S, const InitializedEntity &Entity,
 364                   InitListExpr *IL, QualType &T, bool VerifyOnly,
 365                   bool TreatUnavailableAsInvalid);
 366   bool HadError() { return hadError; }
 367
 368   // @brief Retrieves the fully-structured initializer list used for
 369   // semantic analysis and code generation.
 370   InitListExpr *getFullyStructuredList() const { return FullyStructuredList; }
 371 };
 372
 373 } // end anonymous namespace
 374
 375 ExprResult InitListChecker::PerformEmptyInit(Sema &SemaRef,
 376                                              SourceLocation Loc,
 377                                              const InitializedEntity &Entity,
 378                                              bool VerifyOnly,
 379                                              bool TreatUnavailableAsInvalid) {
 380   InitializationKind Kind = InitializationKind::CreateValue(Loc, Loc, Loc,
 381                                                             true);
 382   MultiExprArg SubInit;
 383   Expr *InitExpr;
 384   InitListExpr DummyInitList(SemaRef.Context, Loc, None, Loc);
 385
 386   // C++ [dcl.init.aggr]p7:
 387   //   If there are fewer initializer-clauses in the list than there are
 388   //   members in the aggregate, then each member not explicitly initialized
 389   //   ...
 390   bool EmptyInitList = SemaRef.getLangOpts().CPlusPlus11 &&
 391       Entity.getType()->getBaseElementTypeUnsafe()->isRecordType();
 392   if (EmptyInitList) {
 393     // C++1y / DR1070:
 394     //   shall be initialized [...] from an empty initializer list.
 395     //
 396     // We apply the resolution of this DR to C++11 but not C++98, since C++98
 397     // does not have useful semantics for initialization from an init list.
 398     // We treat this as copy-initialization, because aggregate initialization
 399     // always performs copy-initialization on its elements.
 400     //
 401     // Only do this if we're initializing a class type, to avoid filling in
 402     // the initializer list where possible.
 403     InitExpr = VerifyOnly ? &DummyInitList : new (SemaRef.Context)
 404                    InitListExpr(SemaRef.Context, Loc, None, Loc);
 405     InitExpr->setType(SemaRef.Context.VoidTy);
 406     SubInit = InitExpr;
 407     Kind = InitializationKind::CreateCopy(Loc, Loc);
 408   } else {
 409     // C++03:
 410     //   shall be value-initialized.
 411   }
 412
 413   InitializationSequence InitSeq(SemaRef, Entity, Kind, SubInit);
 414   // libstdc++4.6 marks the vector default constructor as explicit in
 415   // _GLIBCXX_DEBUG mode, so recover using the C++03 logic in that case.
 416   // stlport does so too. Look for std::__debug for libstdc++, and for
 417   // std:: for stlport.  This is effectively a compiler-side implementation of
 418   // LWG2193.
 419   if (!InitSeq && EmptyInitList && InitSeq.getFailureKind() ==
 420           InitializationSequence::FK_ExplicitConstructor) {
 421     OverloadCandidateSet::iterator Best;
 422     OverloadingResult O =
 423         InitSeq.getFailedCandidateSet()
 424             .BestViableFunction(SemaRef, Kind.getLocation(), Best);
 425     (void)O;
 426     assert(O == OR_Success && "Inconsistent overload resolution");
 427     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
 428     CXXRecordDecl *R = CtorDecl->getParent();
 429
 430     if (CtorDecl->getMinRequiredArguments() == 0 &&
 431         CtorDecl->isExplicit() && R->getDeclName() &&
 432         SemaRef.SourceMgr.isInSystemHeader(CtorDecl->getLocation())) {
 433       bool IsInStd = false;
 434       for (NamespaceDecl *ND = dyn_cast<NamespaceDecl>(R->getDeclContext());
 435            ND && !IsInStd; ND = dyn_cast<NamespaceDecl>(ND->getParent())) {
 436         if (SemaRef.getStdNamespace()->InEnclosingNamespaceSetOf(ND))
 437           IsInStd = true;
 438       }
 439
 440       if (IsInStd && llvm::StringSwitch<bool>(R->getName())
 441               .Cases("basic_string", "deque", "forward_list", true)
 442               .Cases("list", "map", "multimap", "multiset", true)
 443               .Cases("priority_queue", "queue", "set", "stack", true)
 444               .Cases("unordered_map", "unordered_set", "vector", true)
 445               .Default(false)) {
 446         InitSeq.InitializeFrom(
 447             SemaRef, Entity,
 448             InitializationKind::CreateValue(Loc, Loc, Loc, true),
 449             MultiExprArg(), /*TopLevelOfInitList=*/false,
 450             TreatUnavailableAsInvalid);
 451         // Emit a warning for this.  System header warnings aren't shown
 452         // by default, but people working on system headers should see it.
 453         if (!VerifyOnly) {
 454           SemaRef.Diag(CtorDecl->getLocation(),
 455                        diag::warn_invalid_initializer_from_system_header);
 456           if (Entity.getKind() == InitializedEntity::EK_Member)
 457             SemaRef.Diag(Entity.getDecl()->getLocation(),
 458                          diag::note_used_in_initialization_here);
 459           else if (Entity.getKind() == InitializedEntity::EK_ArrayElement)
 460             SemaRef.Diag(Loc, diag::note_used_in_initialization_here);
 461         }
 462       }
 463     }
 464   }
 465   if (!InitSeq) {
 466     if (!VerifyOnly) {
 467       InitSeq.Diagnose(SemaRef, Entity, Kind, SubInit);
 468       if (Entity.getKind() == InitializedEntity::EK_Member)
 469         SemaRef.Diag(Entity.getDecl()->getLocation(),
 470                      diag::note_in_omitted_aggregate_initializer)
 471           << /*field*/1 << Entity.getDecl();
 472       else if (Entity.getKind() == InitializedEntity::EK_ArrayElement) {
 473         bool IsTrailingArrayNewMember =
 474             Entity.getParent() &&
 475             Entity.getParent()->isVariableLengthArrayNew();
 476         SemaRef.Diag(Loc, diag::note_in_omitted_aggregate_initializer)
 477           << (IsTrailingArrayNewMember ? 2 : /*array element*/0)
 478           << Entity.getElementIndex();
 479       }
 480     }
 481     return ExprError();
 482   }
 483
 484   return VerifyOnly ? ExprResult(static_cast<Expr *>(nullptr))
 485                     : InitSeq.Perform(SemaRef, Entity, Kind, SubInit);
 486 }
 487
 488 void InitListChecker::CheckEmptyInitializable(const InitializedEntity &Entity,
 489                                               SourceLocation Loc) {
 490   assert(VerifyOnly &&
 491          "CheckEmptyInitializable is only inteded for verification mode.");
 492   if (PerformEmptyInit(SemaRef, Loc, Entity, /*VerifyOnly*/true,
 493                        TreatUnavailableAsInvalid).isInvalid())
 494     hadError = true;
 495 }
 496
 497 void InitListChecker::FillInEmptyInitForBase(
 498     unsigned Init, const CXXBaseSpecifier &Base,
 499     const InitializedEntity &ParentEntity, InitListExpr *ILE,
 500     bool &RequiresSecondPass, bool FillWithNoInit) {
 501   assert(Init < ILE->getNumInits() && "should have been expanded");
 502
 503   InitializedEntity BaseEntity = InitializedEntity::InitializeBase(
 504       SemaRef.Context, &Base, false, &ParentEntity);
 505
 506   if (!ILE->getInit(Init)) {
 507     ExprResult BaseInit =
 508         FillWithNoInit ? new (SemaRef.Context) NoInitExpr(Base.getType())
 509                        : PerformEmptyInit(SemaRef, ILE->getLocEnd(), BaseEntity,
 510                                           /*VerifyOnly*/ false,
 511                                           TreatUnavailableAsInvalid);
 512     if (BaseInit.isInvalid()) {
 513       hadError = true;
 514       return;
 515     }
 516
 517     ILE->setInit(Init, BaseInit.getAs<Expr>());
 518   } else if (InitListExpr *InnerILE =
 519                  dyn_cast<InitListExpr>(ILE->getInit(Init))) {
 520     FillInEmptyInitializations(BaseEntity, InnerILE,
 521                                RequiresSecondPass, FillWithNoInit);
 522   } else if (DesignatedInitUpdateExpr *InnerDIUE =
 523                dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init))) {
 524     FillInEmptyInitializations(BaseEntity, InnerDIUE->getUpdater(),
 525                                RequiresSecondPass, /*FillWithNoInit =*/true);
 526   }
 527 }
 528
 529 void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
 530                                         const InitializedEntity &ParentEntity,
 531                                               InitListExpr *ILE,
 532                                               bool &RequiresSecondPass,
 533                                               bool FillWithNoInit) {
 534   SourceLocation Loc = ILE->getLocEnd();
 535   unsigned NumInits = ILE->getNumInits();
 536   InitializedEntity MemberEntity
 537     = InitializedEntity::InitializeMember(Field, &ParentEntity);
 538
 539   if (const RecordType *RType = ILE->getType()->getAs<RecordType>())
 540     if (!RType->getDecl()->isUnion())
 541       assert(Init < NumInits && "This ILE should have been expanded");
 542
 543   if (Init >= NumInits || !ILE->getInit(Init)) {
 544     if (FillWithNoInit) {
 545       Expr *Filler = new (SemaRef.Context) NoInitExpr(Field->getType());
 546       if (Init < NumInits)
 547         ILE->setInit(Init, Filler);
 548       else
 549         ILE->updateInit(SemaRef.Context, Init, Filler);
 550       return;
 551     }
 552     // C++1y [dcl.init.aggr]p7:
 553     //   If there are fewer initializer-clauses in the list than there are
 554     //   members in the aggregate, then each member not explicitly initialized
 555     //   shall be initialized from its brace-or-equal-initializer [...]
 556     if (Field->hasInClassInitializer()) {
 557       ExprResult DIE = SemaRef.BuildCXXDefaultInitExpr(Loc, Field);
 558       if (DIE.isInvalid()) {
 559         hadError = true;
 560         return;
 561       }
 562       if (Init < NumInits)
 563         ILE->setInit(Init, DIE.get());
 564       else {
 565         ILE->updateInit(SemaRef.Context, Init, DIE.get());
 566         RequiresSecondPass = true;
 567       }
 568       return;
 569     }
 570
 571     if (Field->getType()->isReferenceType()) {
 572       // C++ [dcl.init.aggr]p9:
 573       //   If an incomplete or empty initializer-list leaves a
 574       //   member of reference type uninitialized, the program is
 575       //   ill-formed.
 576       SemaRef.Diag(Loc, diag::err_init_reference_member_uninitialized)
 577         << Field->getType()
 578         << ILE->getSyntacticForm()->getSourceRange();
 579       SemaRef.Diag(Field->getLocation(),
 580                    diag::note_uninit_reference_member);
 581       hadError = true;
 582       return;
 583     }
 584
 585     ExprResult MemberInit = PerformEmptyInit(SemaRef, Loc, MemberEntity,
 586                                              /*VerifyOnly*/false,
 587                                              TreatUnavailableAsInvalid);
 588     if (MemberInit.isInvalid()) {
 589       hadError = true;
 590       return;
 591     }
 592
 593     if (hadError) {
 594       // Do nothing
 595     } else if (Init < NumInits) {
 596       ILE->setInit(Init, MemberInit.getAs<Expr>());
 597     } else if (!isa<ImplicitValueInitExpr>(MemberInit.get())) {
 598       // Empty initialization requires a constructor call, so
 599       // extend the initializer list to include the constructor
 600       // call and make a note that we'll need to take another pass
 601       // through the initializer list.
 602       ILE->updateInit(SemaRef.Context, Init, MemberInit.getAs<Expr>());
 603       RequiresSecondPass = true;
 604     }
 605   } else if (InitListExpr *InnerILE
 606                = dyn_cast<InitListExpr>(ILE->getInit(Init)))
 607     FillInEmptyInitializations(MemberEntity, InnerILE,
 608                                RequiresSecondPass, FillWithNoInit);
 609   else if (DesignatedInitUpdateExpr *InnerDIUE
 610                = dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init)))
 611     FillInEmptyInitializations(MemberEntity, InnerDIUE->getUpdater(),
 612                                RequiresSecondPass, /*FillWithNoInit =*/ true);
 613 }
 614
 615 /// Recursively replaces NULL values within the given initializer list
 616 /// with expressions that perform value-initialization of the
 617 /// appropriate type.
 618 void
 619 InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
 620                                             InitListExpr *ILE,
 621                                             bool &RequiresSecondPass,
 622                                             bool FillWithNoInit) {
 623   assert((ILE->getType() != SemaRef.Context.VoidTy) &&
 624          "Should not have void type");
 625
 626   // A transparent ILE is not performing aggregate initialization and should
 627   // not be filled in.
 628   if (ILE->isTransparent())
 629     return;
 630
 631   if (const RecordType *RType = ILE->getType()->getAs<RecordType>()) {
 632     const RecordDecl *RDecl = RType->getDecl();
 633     if (RDecl->isUnion() && ILE->getInitializedFieldInUnion())
 634       FillInEmptyInitForField(0, ILE->getInitializedFieldInUnion(),
 635                               Entity, ILE, RequiresSecondPass, FillWithNoInit);
 636     else if (RDecl->isUnion() && isa<CXXRecordDecl>(RDecl) &&
 637              cast<CXXRecordDecl>(RDecl)->hasInClassInitializer()) {
 638       for (auto *Field : RDecl->fields()) {
 639         if (Field->hasInClassInitializer()) {
 640           FillInEmptyInitForField(0, Field, Entity, ILE, RequiresSecondPass,
 641                                   FillWithNoInit);
 642           break;
 643         }
 644       }
 645     } else {
 646       // The fields beyond ILE->getNumInits() are default initialized, so in
 647       // order to leave them uninitialized, the ILE is expanded and the extra
 648       // fields are then filled with NoInitExpr.
 649       unsigned NumElems = numStructUnionElements(ILE->getType());
 650       if (RDecl->hasFlexibleArrayMember())
 651         ++NumElems;
 652       if (ILE->getNumInits() < NumElems)
 653         ILE->resizeInits(SemaRef.Context, NumElems);
 654
 655       unsigned Init = 0;
 656
 657       if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RDecl)) {
 658         for (auto &Base : CXXRD->bases()) {
 659           if (hadError)
 660             return;
 661
 662           FillInEmptyInitForBase(Init, Base, Entity, ILE, RequiresSecondPass,
 663                                  FillWithNoInit);
 664           ++Init;
 665         }
 666       }
 667
 668       for (auto *Field : RDecl->fields()) {
 669         if (Field->isUnnamedBitfield())
 670           continue;
 671
 672         if (hadError)
 673           return;
 674
 675         FillInEmptyInitForField(Init, Field, Entity, ILE, RequiresSecondPass,
 676                                 FillWithNoInit);
 677         if (hadError)
 678           return;
 679
 680         ++Init;
 681
 682         // Only look at the first initialization of a union.
 683         if (RDecl->isUnion())
 684           break;
 685       }
 686     }
 687
 688     return;
 689   }
 690
 691   QualType ElementType;
 692
 693   InitializedEntity ElementEntity = Entity;
 694   unsigned NumInits = ILE->getNumInits();
 695   unsigned NumElements = NumInits;
 696   if (const ArrayType *AType = SemaRef.Context.getAsArrayType(ILE->getType())) {
 697     ElementType = AType->getElementType();
 698     if (const auto *CAType = dyn_cast<ConstantArrayType>(AType))
 699       NumElements = CAType->getSize().getZExtValue();
 700     // For an array new with an unknown bound, ask for one additional element
 701     // in order to populate the array filler.
 702     if (Entity.isVariableLengthArrayNew())
 703       ++NumElements;
 704     ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
 705                                                          0, Entity);
 706   } else if (const VectorType *VType = ILE->getType()->getAs<VectorType>()) {
 707     ElementType = VType->getElementType();
 708     NumElements = VType->getNumElements();
 709     ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
 710                                                          0, Entity);
 711   } else
 712     ElementType = ILE->getType();
 713
 714   for (unsigned Init = 0; Init != NumElements; ++Init) {
 715     if (hadError)
 716       return;
 717
 718     if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement ||
 719         ElementEntity.getKind() == InitializedEntity::EK_VectorElement)
 720       ElementEntity.setElementIndex(Init);
 721
 722     Expr *InitExpr = (Init < NumInits ? ILE->getInit(Init) : nullptr);
 723     if (!InitExpr && Init < NumInits && ILE->hasArrayFiller())
 724       ILE->setInit(Init, ILE->getArrayFiller());
 725     else if (!InitExpr && !ILE->hasArrayFiller()) {
 726       Expr *Filler = nullptr;
 727
 728       if (FillWithNoInit)
 729         Filler = new (SemaRef.Context) NoInitExpr(ElementType);
 730       else {
 731         ExprResult ElementInit = PerformEmptyInit(SemaRef, ILE->getLocEnd(),
 732                                                   ElementEntity,
 733                                                   /*VerifyOnly*/false,
 734                                                   TreatUnavailableAsInvalid);
 735         if (ElementInit.isInvalid()) {
 736           hadError = true;
 737           return;
 738         }
 739
 740         Filler = ElementInit.getAs<Expr>();
 741       }
 742
 743       if (hadError) {
 744         // Do nothing
 745       } else if (Init < NumInits) {
 746         // For arrays, just set the expression used for value-initialization
 747         // of the "holes" in the array.
 748         if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement)
 749           ILE->setArrayFiller(Filler);
 750         else
 751           ILE->setInit(Init, Filler);
 752       } else {
 753         // For arrays, just set the expression used for value-initialization
 754         // of the rest of elements and exit.
 755         if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement) {
 756           ILE->setArrayFiller(Filler);
 757           return;
 758         }
 759
 760         if (!isa<ImplicitValueInitExpr>(Filler) && !isa<NoInitExpr>(Filler)) {
 761           // Empty initialization requires a constructor call, so
 762           // extend the initializer list to include the constructor
 763           // call and make a note that we'll need to take another pass
 764           // through the initializer list.
 765           ILE->updateInit(SemaRef.Context, Init, Filler);
 766           RequiresSecondPass = true;
 767         }
 768       }
 769     } else if (InitListExpr *InnerILE
 770                  = dyn_cast_or_null<InitListExpr>(InitExpr))
 771       FillInEmptyInitializations(ElementEntity, InnerILE, RequiresSecondPass,
 772                                  FillWithNoInit);
 773     else if (DesignatedInitUpdateExpr *InnerDIUE
 774                  = dyn_cast_or_null<DesignatedInitUpdateExpr>(InitExpr))
 775       FillInEmptyInitializations(ElementEntity, InnerDIUE->getUpdater(),
 776                                  RequiresSecondPass, /*FillWithNoInit =*/ true);
 777   }
 778 }
 779
 780 InitListChecker::InitListChecker(Sema &S, const InitializedEntity &Entity,
 781                                  InitListExpr *IL, QualType &T,
 782                                  bool VerifyOnly,
 783                                  bool TreatUnavailableAsInvalid)
 784   : SemaRef(S), VerifyOnly(VerifyOnly),
 785     TreatUnavailableAsInvalid(TreatUnavailableAsInvalid) {
 786   // FIXME: Check that IL isn't already the semantic form of some other
 787   // InitListExpr. If it is, we'd create a broken AST.
 788
 789   hadError = false;
 790
 791   FullyStructuredList =
 792       getStructuredSubobjectInit(IL, 0, T, nullptr, 0, IL->getSourceRange());
 793   CheckExplicitInitList(Entity, IL, T, FullyStructuredList,
 794                         /*TopLevelObject=*/true);
 795
 796   if (!hadError && !VerifyOnly) {
 797     bool RequiresSecondPass = false;
 798     FillInEmptyInitializations(Entity, FullyStructuredList, RequiresSecondPass);
 799     if (RequiresSecondPass && !hadError)
 800       FillInEmptyInitializations(Entity, FullyStructuredList,
 801                                  RequiresSecondPass);
 802   }
 803 }
 804
 805 int InitListChecker::numArrayElements(QualType DeclType) {
 806   // FIXME: use a proper constant
 807   int maxElements = 0x7FFFFFFF;
 808   if (const ConstantArrayType *CAT =
 809         SemaRef.Context.getAsConstantArrayType(DeclType)) {
 810     maxElements = static_cast<int>(CAT->getSize().getZExtValue());
 811   }
 812   return maxElements;
 813 }
 814
 815 int InitListChecker::numStructUnionElements(QualType DeclType) {
 816   RecordDecl *structDecl = DeclType->getAs<RecordType>()->getDecl();
 817   int InitializableMembers = 0;
 818   if (auto *CXXRD = dyn_cast<CXXRecordDecl>(structDecl))
 819     InitializableMembers += CXXRD->getNumBases();
 820   for (const auto *Field : structDecl->fields())
 821     if (!Field->isUnnamedBitfield())
 822       ++InitializableMembers;
 823
 824   if (structDecl->isUnion())
 825     return std::min(InitializableMembers, 1);
 826   return InitializableMembers - structDecl->hasFlexibleArrayMember();
 827 }
 828
 829 /// Determine whether Entity is an entity for which it is idiomatic to elide
 830 /// the braces in aggregate initialization.
 831 static bool isIdiomaticBraceElisionEntity(const InitializedEntity &Entity) {
 832   // Recursive initialization of the one and only field within an aggregate
 833   // class is considered idiomatic. This case arises in particular for
 834   // initialization of std::array, where the C++ standard suggests the idiom of
 835   //
 836   //   std::array<T, N> arr = {1, 2, 3};
 837   //
 838   // (where std::array is an aggregate struct containing a single array field.
 839
 840   // FIXME: Should aggregate initialization of a struct with a single
 841   // base class and no members also suppress the warning?
 842   if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
 843     return false;
 844
 845   auto *ParentRD =
 846       Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
 847   if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
 848     if (CXXRD->getNumBases())
 849       return false;
 850
 851   auto FieldIt = ParentRD->field_begin();
 852   assert(FieldIt != ParentRD->field_end() &&
 853          "no fields but have initializer for member?");
 854   return ++FieldIt == ParentRD->field_end();
 855 }
 856
 857 /// Check whether the range of the initializer \p ParentIList from element
 858 /// \p Index onwards can be used to initialize an object of type \p T. Update
 859 /// \p Index to indicate how many elements of the list were consumed.
 860 ///
 861 /// This also fills in \p StructuredList, from element \p StructuredIndex
 862 /// onwards, with the fully-braced, desugared form of the initialization.
 863 void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
 864                                             InitListExpr *ParentIList,
 865                                             QualType T, unsigned &Index,
 866                                             InitListExpr *StructuredList,
 867                                             unsigned &StructuredIndex) {
 868   int maxElements = 0;
 869
 870   if (T->isArrayType())
 871     maxElements = numArrayElements(T);
 872   else if (T->isRecordType())
 873     maxElements = numStructUnionElements(T);
 874   else if (T->isVectorType())
 875     maxElements = T->getAs<VectorType>()->getNumElements();
 876   else
 877     llvm_unreachable("CheckImplicitInitList(): Illegal type");
 878
 879   if (maxElements == 0) {
 880     if (!VerifyOnly)
 881       SemaRef.Diag(ParentIList->getInit(Index)->getLocStart(),
 882                    diag::err_implicit_empty_initializer);
 883     ++Index;
 884     hadError = true;
 885     return;
 886   }
 887
 888   // Build a structured initializer list corresponding to this subobject.
 889   InitListExpr *StructuredSubobjectInitList
 890     = getStructuredSubobjectInit(ParentIList, Index, T, StructuredList,
 891                                  StructuredIndex,
 892           SourceRange(ParentIList->getInit(Index)->getLocStart(),
 893                       ParentIList->getSourceRange().getEnd()));
 894   unsigned StructuredSubobjectInitIndex = 0;
 895
 896   // Check the element types and build the structural subobject.
 897   unsigned StartIndex = Index;
 898   CheckListElementTypes(Entity, ParentIList, T,
 899                         /*SubobjectIsDesignatorContext=*/false, Index,
 900                         StructuredSubobjectInitList,
 901                         StructuredSubobjectInitIndex);
 902
 903   if (!VerifyOnly) {
 904     StructuredSubobjectInitList->setType(T);
 905
 906     unsigned EndIndex = (Index == StartIndex? StartIndex : Index - 1);
 907     // Update the structured sub-object initializer so that it's ending
 908     // range corresponds with the end of the last initializer it used.
 909     if (EndIndex < ParentIList->getNumInits() &&
 910         ParentIList->getInit(EndIndex)) {
 911       SourceLocation EndLoc
 912         = ParentIList->getInit(EndIndex)->getSourceRange().getEnd();
 913       StructuredSubobjectInitList->setRBraceLoc(EndLoc);
 914     }
 915
 916     // Complain about missing braces.
 917     if ((T->isArrayType() || T->isRecordType()) &&
 918         !ParentIList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) &&
 919         !isIdiomaticBraceElisionEntity(Entity)) {
 920       SemaRef.Diag(StructuredSubobjectInitList->getLocStart(),
 921                    diag::warn_missing_braces)
 922           << StructuredSubobjectInitList->getSourceRange()
 923           << FixItHint::CreateInsertion(
 924                  StructuredSubobjectInitList->getLocStart(), "{")
 925           << FixItHint::CreateInsertion(
 926                  SemaRef.getLocForEndOfToken(
 927                      StructuredSubobjectInitList->getLocEnd()),
 928                  "}");
 929     }
 930   }
 931 }
 932
 933 /// Warn that \p Entity was of scalar type and was initialized by a
 934 /// single-element braced initializer list.
 935 static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
 936                                  SourceRange Braces) {
 937   // Don't warn during template instantiation. If the initialization was
 938   // non-dependent, we warned during the initial parse; otherwise, the
 939   // type might not be scalar in some uses of the template.
 940   if (S.inTemplateInstantiation())
 941     return;
 942
 943   unsigned DiagID = 0;
 944
 945   switch (Entity.getKind()) {
 946   case InitializedEntity::EK_VectorElement:
 947   case InitializedEntity::EK_ComplexElement:
 948   case InitializedEntity::EK_ArrayElement:
 949   case InitializedEntity::EK_Parameter:
 950   case InitializedEntity::EK_Parameter_CF_Audited:
 951   case InitializedEntity::EK_Result:
 952     // Extra braces here are suspicious.
 953     DiagID = diag::warn_braces_around_scalar_init;
 954     break;
 955
 956   case InitializedEntity::EK_Member:
 957     // Warn on aggregate initialization but not on ctor init list or
 958     // default member initializer.
 959     if (Entity.getParent())
 960       DiagID = diag::warn_braces_around_scalar_init;
 961     break;
 962
 963   case InitializedEntity::EK_Variable:
 964   case InitializedEntity::EK_LambdaCapture:
 965     // No warning, might be direct-list-initialization.
 966     // FIXME: Should we warn for copy-list-initialization in these cases?
 967     break;
 968
 969   case InitializedEntity::EK_New:
 970   case InitializedEntity::EK_Temporary:
 971   case InitializedEntity::EK_CompoundLiteralInit:
 972     // No warning, braces are part of the syntax of the underlying construct.
 973     break;
 974
 975   case InitializedEntity::EK_RelatedResult:
 976     // No warning, we already warned when initializing the result.
 977     break;
 978
 979   case InitializedEntity::EK_Exception:
 980   case InitializedEntity::EK_Base:
 981   case InitializedEntity::EK_Delegating:
 982   case InitializedEntity::EK_BlockElement:
 983   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
 984   case InitializedEntity::EK_Binding:
 985     llvm_unreachable("unexpected braced scalar init");
 986   }
 987
 988   if (DiagID) {
 989     S.Diag(Braces.getBegin(), DiagID)
 990       << Braces
 991       << FixItHint::CreateRemoval(Braces.getBegin())
 992       << FixItHint::CreateRemoval(Braces.getEnd());
 993   }
 994 }
 995
 996 /// Check whether the initializer \p IList (that was written with explicit
 997 /// braces) can be used to initialize an object of type \p T.
 998 ///
 999 /// This also fills in \p StructuredList with the fully-braced, desugared
1000 /// form of the initialization.
1001 void InitListChecker::CheckExplicitInitList(const InitializedEntity &Entity,
1002                                             InitListExpr *IList, QualType &T,
1003                                             InitListExpr *StructuredList,
1004                                             bool TopLevelObject) {
1005   if (!VerifyOnly) {
1006     SyntacticToSemantic[IList] = StructuredList;
1007     StructuredList->setSyntacticForm(IList);
1008   }
1009
1010   unsigned Index = 0, StructuredIndex = 0;
1011   CheckListElementTypes(Entity, IList, T, /*SubobjectIsDesignatorContext=*/true,
1012                         Index, StructuredList, StructuredIndex, TopLevelObject);
1013   if (!VerifyOnly) {
1014     QualType ExprTy = T;
1015     if (!ExprTy->isArrayType())
1016       ExprTy = ExprTy.getNonLValueExprType(SemaRef.Context);
1017     IList->setType(ExprTy);
1018     StructuredList->setType(ExprTy);
1019   }
1020   if (hadError)
1021     return;
1022
1023   if (Index < IList->getNumInits()) {
1024     // We have leftover initializers
1025     if (VerifyOnly) {
1026       if (SemaRef.getLangOpts().CPlusPlus ||
1027           (SemaRef.getLangOpts().OpenCL &&
1028            IList->getType()->isVectorType())) {
1029         hadError = true;
1030       }
1031       return;
1032     }
1033
1034     if (StructuredIndex == 1 &&
1035         IsStringInit(StructuredList->getInit(0), T, SemaRef.Context) ==
1036             SIF_None) {
1037       unsigned DK = diag::ext_excess_initializers_in_char_array_initializer;
1038       if (SemaRef.getLangOpts().CPlusPlus) {
1039         DK = diag::err_excess_initializers_in_char_array_initializer;
1040         hadError = true;
1041       }
1042       // Special-case
1043       SemaRef.Diag(IList->getInit(Index)->getLocStart(), DK)
1044         << IList->getInit(Index)->getSourceRange();
1045     } else if (!T->isIncompleteType()) {
1046       // Don't complain for incomplete types, since we'll get an error
1047       // elsewhere
1048       QualType CurrentObjectType = StructuredList->getType();
1049       int initKind =
1050         CurrentObjectType->isArrayType()? 0 :
1051         CurrentObjectType->isVectorType()? 1 :
1052         CurrentObjectType->isScalarType()? 2 :
1053         CurrentObjectType->isUnionType()? 3 :
1054         4;
1055
1056       unsigned DK = diag::ext_excess_initializers;
1057       if (SemaRef.getLangOpts().CPlusPlus) {
1058         DK = diag::err_excess_initializers;
1059         hadError = true;
1060       }
1061       if (SemaRef.getLangOpts().OpenCL && initKind == 1) {
1062         DK = diag::err_excess_initializers;
1063         hadError = true;
1064       }
1065
1066       SemaRef.Diag(IList->getInit(Index)->getLocStart(), DK)
1067         << initKind << IList->getInit(Index)->getSourceRange();
1068     }
1069   }
1070
1071   if (!VerifyOnly && T->isScalarType() &&
1072       IList->getNumInits() == 1 && !isa<InitListExpr>(IList->getInit(0)))
1073     warnBracedScalarInit(SemaRef, Entity, IList->getSourceRange());
1074 }
1075
1076 void InitListChecker::CheckListElementTypes(const InitializedEntity &Entity,
1077                                             InitListExpr *IList,
1078                                             QualType &DeclType,
1079                                             bool SubobjectIsDesignatorContext,
1080                                             unsigned &Index,
1081                                             InitListExpr *StructuredList,
1082                                             unsigned &StructuredIndex,
1083                                             bool TopLevelObject) {
1084   if (DeclType->isAnyComplexType() && SubobjectIsDesignatorContext) {
1085     // Explicitly braced initializer for complex type can be real+imaginary
1086     // parts.
1087     CheckComplexType(Entity, IList, DeclType, Index,
1088                      StructuredList, StructuredIndex);
1089   } else if (DeclType->isScalarType()) {
1090     CheckScalarType(Entity, IList, DeclType, Index,
1091                     StructuredList, StructuredIndex);
1092   } else if (DeclType->isVectorType()) {
1093     CheckVectorType(Entity, IList, DeclType, Index,
1094                     StructuredList, StructuredIndex);
1095   } else if (DeclType->isRecordType()) {
1096     assert(DeclType->isAggregateType() &&
1097            "non-aggregate records should be handed in CheckSubElementType");
1098     RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
1099     auto Bases =
1100         CXXRecordDecl::base_class_range(CXXRecordDecl::base_class_iterator(),
1101                                         CXXRecordDecl::base_class_iterator());
1102     if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
1103       Bases = CXXRD->bases();
1104     CheckStructUnionTypes(Entity, IList, DeclType, Bases, RD->field_begin(),
1105                           SubobjectIsDesignatorContext, Index, StructuredList,
1106                           StructuredIndex, TopLevelObject);
1107   } else if (DeclType->isArrayType()) {
1108     llvm::APSInt Zero(
1109                     SemaRef.Context.getTypeSize(SemaRef.Context.getSizeType()),
1110                     false);
1111     CheckArrayType(Entity, IList, DeclType, Zero,
1112                    SubobjectIsDesignatorContext, Index,
1113                    StructuredList, StructuredIndex);
1114   } else if (DeclType->isVoidType() || DeclType->isFunctionType()) {
1115     // This type is invalid, issue a diagnostic.
1116     ++Index;
1117     if (!VerifyOnly)
1118       SemaRef.Diag(IList->getLocStart(), diag::err_illegal_initializer_type)
1119         << DeclType;
1120     hadError = true;
1121   } else if (DeclType->isReferenceType()) {
1122     CheckReferenceType(Entity, IList, DeclType, Index,
1123                        StructuredList, StructuredIndex);
1124   } else if (DeclType->isObjCObjectType()) {
1125     if (!VerifyOnly)
1126       SemaRef.Diag(IList->getLocStart(), diag::err_init_objc_class)
1127         << DeclType;
1128     hadError = true;
1129   } else {
1130     if (!VerifyOnly)
1131       SemaRef.Diag(IList->getLocStart(), diag::err_illegal_initializer_type)
1132         << DeclType;
1133     hadError = true;
1134   }
1135 }
1136
1137 void InitListChecker::CheckSubElementType(const InitializedEntity &Entity,
1138                                           InitListExpr *IList,
1139                                           QualType ElemType,
1140                                           unsigned &Index,
1141                                           InitListExpr *StructuredList,
1142                                           unsigned &StructuredIndex) {
1143   Expr *expr = IList->getInit(Index);
1144
1145   if (ElemType->isReferenceType())
1146     return CheckReferenceType(Entity, IList, ElemType, Index,
1147                               StructuredList, StructuredIndex);
1148
1149   if (InitListExpr *SubInitList = dyn_cast<InitListExpr>(expr)) {
1150     if (SubInitList->getNumInits() == 1 &&
1151         IsStringInit(SubInitList->getInit(0), ElemType, SemaRef.Context) ==
1152         SIF_None) {
1153       expr = SubInitList->getInit(0);
1154     } else if (!SemaRef.getLangOpts().CPlusPlus) {
1155       InitListExpr *InnerStructuredList
1156         = getStructuredSubobjectInit(IList, Index, ElemType,
1157                                      StructuredList, StructuredIndex,
1158                                      SubInitList->getSourceRange(), true);
1159       CheckExplicitInitList(Entity, SubInitList, ElemType,
1160                             InnerStructuredList);
1161
1162       if (!hadError && !VerifyOnly) {
1163         bool RequiresSecondPass = false;
1164         FillInEmptyInitializations(Entity, InnerStructuredList,
1165                                    RequiresSecondPass);
1166         if (RequiresSecondPass && !hadError)
1167           FillInEmptyInitializations(Entity, InnerStructuredList,
1168                                      RequiresSecondPass);
1169       }
1170       ++StructuredIndex;
1171       ++Index;
1172       return;
1173     }
1174     // C++ initialization is handled later.
1175   } else if (isa<ImplicitValueInitExpr>(expr)) {
1176     // This happens during template instantiation when we see an InitListExpr
1177     // that we've already checked once.
1178     assert(SemaRef.Context.hasSameType(expr->getType(), ElemType) &&
1179            "found implicit initialization for the wrong type");
1180     if (!VerifyOnly)
1181       UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1182     ++Index;
1183     return;
1184   }
1185
1186   if (SemaRef.getLangOpts().CPlusPlus) {
1187     // C++ [dcl.init.aggr]p2:
1188     //   Each member is copy-initialized from the corresponding
1189     //   initializer-clause.
1190
1191     // FIXME: Better EqualLoc?
1192     InitializationKind Kind =
1193       InitializationKind::CreateCopy(expr->getLocStart(), SourceLocation());
1194     InitializationSequence Seq(SemaRef, Entity, Kind, expr,
1195                                /*TopLevelOfInitList*/ true);
1196
1197     // C++14 [dcl.init.aggr]p13:
1198     //   If the assignment-expression can initialize a member, the member is
1199     //   initialized. Otherwise [...] brace elision is assumed
1200     //
1201     // Brace elision is never performed if the element is not an
1202     // assignment-expression.
1203     if (Seq || isa<InitListExpr>(expr)) {
1204       if (!VerifyOnly) {
1205         ExprResult Result =
1206           Seq.Perform(SemaRef, Entity, Kind, expr);
1207         if (Result.isInvalid())
1208           hadError = true;
1209
1210         UpdateStructuredListElement(StructuredList, StructuredIndex,
1211                                     Result.getAs<Expr>());
1212       } else if (!Seq)
1213         hadError = true;
1214       ++Index;
1215       return;
1216     }
1217
1218     // Fall through for subaggregate initialization
1219   } else if (ElemType->isScalarType() || ElemType->isAtomicType()) {
1220     // FIXME: Need to handle atomic aggregate types with implicit init lists.
1221     return CheckScalarType(Entity, IList, ElemType, Index,
1222                            StructuredList, StructuredIndex);
1223   } else if (const ArrayType *arrayType =
1224                  SemaRef.Context.getAsArrayType(ElemType)) {
1225     // arrayType can be incomplete if we're initializing a flexible
1226     // array member.  There's nothing we can do with the completed
1227     // type here, though.
1228
1229     if (IsStringInit(expr, arrayType, SemaRef.Context) == SIF_None) {
1230       if (!VerifyOnly) {
1231         CheckStringInit(expr, ElemType, arrayType, SemaRef);
1232         UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1233       }
1234       ++Index;
1235       return;
1236     }
1237
1238     // Fall through for subaggregate initialization.
1239
1240   } else {
1241     assert((ElemType->isRecordType() || ElemType->isVectorType() ||
1242             ElemType->isOpenCLSpecificType()) && "Unexpected type");
1243
1244     // C99 6.7.8p13:
1245     //
1246     //   The initializer for a structure or union object that has
1247     //   automatic storage duration shall be either an initializer
1248     //   list as described below, or a single expression that has
1249     //   compatible structure or union type. In the latter case, the
1250     //   initial value of the object, including unnamed members, is
1251     //   that of the expression.
1252     ExprResult ExprRes = expr;
1253     if (SemaRef.CheckSingleAssignmentConstraints(
1254             ElemType, ExprRes, !VerifyOnly) != Sema::Incompatible) {
1255       if (ExprRes.isInvalid())
1256         hadError = true;
1257       else {
1258         ExprRes = SemaRef.DefaultFunctionArrayLvalueConversion(ExprRes.get());
1259           if (ExprRes.isInvalid())
1260             hadError = true;
1261       }
1262       UpdateStructuredListElement(StructuredList, StructuredIndex,
1263                                   ExprRes.getAs<Expr>());
1264       ++Index;
1265       return;
1266     }
1267     ExprRes.get();
1268     // Fall through for subaggregate initialization
1269   }
1270
1271   // C++ [dcl.init.aggr]p12:
1272   //
1273   //   [...] Otherwise, if the member is itself a non-empty
1274   //   subaggregate, brace elision is assumed and the initializer is
1275   //   considered for the initialization of the first member of
1276   //   the subaggregate.
1277   // OpenCL vector initializer is handled elsewhere.
1278   if ((!SemaRef.getLangOpts().OpenCL && ElemType->isVectorType()) ||
1279       ElemType->isAggregateType()) {
1280     CheckImplicitInitList(Entity, IList, ElemType, Index, StructuredList,
1281                           StructuredIndex);
1282     ++StructuredIndex;
1283   } else {
1284     if (!VerifyOnly) {
1285       // We cannot initialize this element, so let
1286       // PerformCopyInitialization produce the appropriate diagnostic.
1287       SemaRef.PerformCopyInitialization(Entity, SourceLocation(), expr,
1288                                         /*TopLevelOfInitList=*/true);
1289     }
1290     hadError = true;
1291     ++Index;
1292     ++StructuredIndex;
1293   }
1294 }
1295
1296 void InitListChecker::CheckComplexType(const InitializedEntity &Entity,
1297                                        InitListExpr *IList, QualType DeclType,
1298                                        unsigned &Index,
1299                                        InitListExpr *StructuredList,
1300                                        unsigned &StructuredIndex) {
1301   assert(Index == 0 && "Index in explicit init list must be zero");
1302
1303   // As an extension, clang supports complex initializers, which initialize
1304   // a complex number component-wise.  When an explicit initializer list for
1305   // a complex number contains two two initializers, this extension kicks in:
1306   // it exepcts the initializer list to contain two elements convertible to
1307   // the element type of the complex type. The first element initializes
1308   // the real part, and the second element intitializes the imaginary part.
1309
1310   if (IList->getNumInits() != 2)
1311     return CheckScalarType(Entity, IList, DeclType, Index, StructuredList,
1312                            StructuredIndex);
1313
1314   // This is an extension in C.  (The builtin _Complex type does not exist
1315   // in the C++ standard.)
1316   if (!SemaRef.getLangOpts().CPlusPlus && !VerifyOnly)
1317     SemaRef.Diag(IList->getLocStart(), diag::ext_complex_component_init)
1318       << IList->getSourceRange();
1319
1320   // Initialize the complex number.
1321   QualType elementType = DeclType->getAs<ComplexType>()->getElementType();
1322   InitializedEntity ElementEntity =
1323     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1324
1325   for (unsigned i = 0; i < 2; ++i) {
1326     ElementEntity.setElementIndex(Index);
1327     CheckSubElementType(ElementEntity, IList, elementType, Index,
1328                         StructuredList, StructuredIndex);
1329   }
1330 }
1331
1332 void InitListChecker::CheckScalarType(const InitializedEntity &Entity,
1333                                       InitListExpr *IList, QualType DeclType,
1334                                       unsigned &Index,
1335                                       InitListExpr *StructuredList,
1336                                       unsigned &StructuredIndex) {
1337   if (Index >= IList->getNumInits()) {
1338     if (!VerifyOnly)
1339       SemaRef.Diag(IList->getLocStart(),
1340                    SemaRef.getLangOpts().CPlusPlus11 ?
1341                      diag::warn_cxx98_compat_empty_scalar_initializer :
1342                      diag::err_empty_scalar_initializer)
1343         << IList->getSourceRange();
1344     hadError = !SemaRef.getLangOpts().CPlusPlus11;
1345     ++Index;
1346     ++StructuredIndex;
1347     return;
1348   }
1349
1350   Expr *expr = IList->getInit(Index);
1351   if (InitListExpr *SubIList = dyn_cast<InitListExpr>(expr)) {
1352     // FIXME: This is invalid, and accepting it causes overload resolution
1353     // to pick the wrong overload in some corner cases.
1354     if (!VerifyOnly)
1355       SemaRef.Diag(SubIList->getLocStart(),
1356                    diag::ext_many_braces_around_scalar_init)
1357         << SubIList->getSourceRange();
1358
1359     CheckScalarType(Entity, SubIList, DeclType, Index, StructuredList,
1360                     StructuredIndex);
1361     return;
1362   } else if (isa<DesignatedInitExpr>(expr)) {
1363     if (!VerifyOnly)
1364       SemaRef.Diag(expr->getLocStart(),
1365                    diag::err_designator_for_scalar_init)
1366         << DeclType << expr->getSourceRange();
1367     hadError = true;
1368     ++Index;
1369     ++StructuredIndex;
1370     return;
1371   }
1372
1373   if (VerifyOnly) {
1374     if (!SemaRef.CanPerformCopyInitialization(Entity,expr))
1375       hadError = true;
1376     ++Index;
1377     return;
1378   }
1379
1380   ExprResult Result =
1381     SemaRef.PerformCopyInitialization(Entity, expr->getLocStart(), expr,
1382                                       /*TopLevelOfInitList=*/true);
1383
1384   Expr *ResultExpr = nullptr;
1385
1386   if (Result.isInvalid())
1387     hadError = true; // types weren't compatible.
1388   else {
1389     ResultExpr = Result.getAs<Expr>();
1390
1391     if (ResultExpr != expr) {
1392       // The type was promoted, update initializer list.
1393       IList->setInit(Index, ResultExpr);
1394     }
1395   }
1396   if (hadError)
1397     ++StructuredIndex;
1398   else
1399     UpdateStructuredListElement(StructuredList, StructuredIndex, ResultExpr);
1400   ++Index;
1401 }
1402
1403 void InitListChecker::CheckReferenceType(const InitializedEntity &Entity,
1404                                          InitListExpr *IList, QualType DeclType,
1405                                          unsigned &Index,
1406                                          InitListExpr *StructuredList,
1407                                          unsigned &StructuredIndex) {
1408   if (Index >= IList->getNumInits()) {
1409     // FIXME: It would be wonderful if we could point at the actual member. In
1410     // general, it would be useful to pass location information down the stack,
1411     // so that we know the location (or decl) of the "current object" being
1412     // initialized.
1413     if (!VerifyOnly)
1414       SemaRef.Diag(IList->getLocStart(),
1415                     diag::err_init_reference_member_uninitialized)
1416         << DeclType
1417         << IList->getSourceRange();
1418     hadError = true;
1419     ++Index;
1420     ++StructuredIndex;
1421     return;
1422   }
1423
1424   Expr *expr = IList->getInit(Index);
1425   if (isa<InitListExpr>(expr) && !SemaRef.getLangOpts().CPlusPlus11) {
1426     if (!VerifyOnly)
1427       SemaRef.Diag(IList->getLocStart(), diag::err_init_non_aggr_init_list)
1428         << DeclType << IList->getSourceRange();
1429     hadError = true;
1430     ++Index;
1431     ++StructuredIndex;
1432     return;
1433   }
1434
1435   if (VerifyOnly) {
1436     if (!SemaRef.CanPerformCopyInitialization(Entity,expr))
1437       hadError = true;
1438     ++Index;
1439     return;
1440   }
1441
1442   ExprResult Result =
1443       SemaRef.PerformCopyInitialization(Entity, expr->getLocStart(), expr,
1444                                         /*TopLevelOfInitList=*/true);
1445
1446   if (Result.isInvalid())
1447     hadError = true;
1448
1449   expr = Result.getAs<Expr>();
1450   IList->setInit(Index, expr);
1451
1452   if (hadError)
1453     ++StructuredIndex;
1454   else
1455     UpdateStructuredListElement(StructuredList, StructuredIndex, expr);
1456   ++Index;
1457 }
1458
1459 void InitListChecker::CheckVectorType(const InitializedEntity &Entity,
1460                                       InitListExpr *IList, QualType DeclType,
1461                                       unsigned &Index,
1462                                       InitListExpr *StructuredList,
1463                                       unsigned &StructuredIndex) {
1464   const VectorType *VT = DeclType->getAs<VectorType>();
1465   unsigned maxElements = VT->getNumElements();
1466   unsigned numEltsInit = 0;
1467   QualType elementType = VT->getElementType();
1468
1469   if (Index >= IList->getNumInits()) {
1470     // Make sure the element type can be value-initialized.
1471     if (VerifyOnly)
1472       CheckEmptyInitializable(
1473           InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity),
1474           IList->getLocEnd());
1475     return;
1476   }
1477
1478   if (!SemaRef.getLangOpts().OpenCL) {
1479     // If the initializing element is a vector, try to copy-initialize
1480     // instead of breaking it apart (which is doomed to failure anyway).
1481     Expr *Init = IList->getInit(Index);
1482     if (!isa<InitListExpr>(Init) && Init->getType()->isVectorType()) {
1483       if (VerifyOnly) {
1484         if (!SemaRef.CanPerformCopyInitialization(Entity, Init))
1485           hadError = true;
1486         ++Index;
1487         return;
1488       }
1489
1490   ExprResult Result =
1491       SemaRef.PerformCopyInitialization(Entity, Init->getLocStart(), Init,
1492                                         /*TopLevelOfInitList=*/true);
1493
1494       Expr *ResultExpr = nullptr;
1495       if (Result.isInvalid())
1496         hadError = true; // types weren't compatible.
1497       else {
1498         ResultExpr = Result.getAs<Expr>();
1499
1500         if (ResultExpr != Init) {
1501           // The type was promoted, update initializer list.
1502           IList->setInit(Index, ResultExpr);
1503         }
1504       }
1505       if (hadError)
1506         ++StructuredIndex;
1507       else
1508         UpdateStructuredListElement(StructuredList, StructuredIndex,
1509                                     ResultExpr);
1510       ++Index;
1511       return;
1512     }
1513
1514     InitializedEntity ElementEntity =
1515       InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1516
1517     for (unsigned i = 0; i < maxElements; ++i, ++numEltsInit) {
1518       // Don't attempt to go past the end of the init list
1519       if (Index >= IList->getNumInits()) {
1520         if (VerifyOnly)
1521           CheckEmptyInitializable(ElementEntity, IList->getLocEnd());
1522         break;
1523       }
1524
1525       ElementEntity.setElementIndex(Index);
1526       CheckSubElementType(ElementEntity, IList, elementType, Index,
1527                           StructuredList, StructuredIndex);
1528     }
1529
1530     if (VerifyOnly)
1531       return;
1532
1533     bool isBigEndian = SemaRef.Context.getTargetInfo().isBigEndian();
1534     const VectorType *T = Entity.getType()->getAs<VectorType>();
1535     if (isBigEndian && (T->getVectorKind() == VectorType::NeonVector ||
1536                         T->getVectorKind() == VectorType::NeonPolyVector)) {
1537       // The ability to use vector initializer lists is a GNU vector extension
1538       // and is unrelated to the NEON intrinsics in arm_neon.h. On little
1539       // endian machines it works fine, however on big endian machines it
1540       // exhibits surprising behaviour:
1541       //
1542       //   uint32x2_t x = {42, 64};
1543       //   return vget_lane_u32(x, 0); // Will return 64.
1544       //
1545       // Because of this, explicitly call out that it is non-portable.
1546       //
1547       SemaRef.Diag(IList->getLocStart(),
1548                    diag::warn_neon_vector_initializer_non_portable);
1549
1550       const char *typeCode;
1551       unsigned typeSize = SemaRef.Context.getTypeSize(elementType);
1552
1553       if (elementType->isFloatingType())
1554         typeCode = "f";
1555       else if (elementType->isSignedIntegerType())
1556         typeCode = "s";
1557       else if (elementType->isUnsignedIntegerType())
1558         typeCode = "u";
1559       else
1560         llvm_unreachable("Invalid element type!");
1561
1562       SemaRef.Diag(IList->getLocStart(),
1563                    SemaRef.Context.getTypeSize(VT) > 64 ?
1564                    diag::note_neon_vector_initializer_non_portable_q :
1565                    diag::note_neon_vector_initializer_non_portable)
1566         << typeCode << typeSize;
1567     }
1568
1569     return;
1570   }
1571
1572   InitializedEntity ElementEntity =
1573     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
1574
1575   // OpenCL initializers allows vectors to be constructed from vectors.
1576   for (unsigned i = 0; i < maxElements; ++i) {
1577     // Don't attempt to go past the end of the init list
1578     if (Index >= IList->getNumInits())
1579       break;
1580
1581     ElementEntity.setElementIndex(Index);
1582
1583     QualType IType = IList->getInit(Index)->getType();
1584     if (!IType->isVectorType()) {
1585       CheckSubElementType(ElementEntity, IList, elementType, Index,
1586                           StructuredList, StructuredIndex);
1587       ++numEltsInit;
1588     } else {
1589       QualType VecType;
1590       const VectorType *IVT = IType->getAs<VectorType>();
1591       unsigned numIElts = IVT->getNumElements();
1592
1593       if (IType->isExtVectorType())
1594         VecType = SemaRef.Context.getExtVectorType(elementType, numIElts);
1595       else
1596         VecType = SemaRef.Context.getVectorType(elementType, numIElts,
1597                                                 IVT->getVectorKind());
1598       CheckSubElementType(ElementEntity, IList, VecType, Index,
1599                           StructuredList, StructuredIndex);
1600       numEltsInit += numIElts;
1601     }
1602   }
1603
1604   // OpenCL requires all elements to be initialized.
1605   if (numEltsInit != maxElements) {
1606     if (!VerifyOnly)
1607       SemaRef.Diag(IList->getLocStart(),
1608                    diag::err_vector_incorrect_num_initializers)
1609         << (numEltsInit < maxElements) << maxElements << numEltsInit;
1610     hadError = true;
1611   }
1612 }
1613
1614 void InitListChecker::CheckArrayType(const InitializedEntity &Entity,
1615                                      InitListExpr *IList, QualType &DeclType,
1616                                      llvm::APSInt elementIndex,
1617                                      bool SubobjectIsDesignatorContext,
1618                                      unsigned &Index,
1619                                      InitListExpr *StructuredList,
1620                                      unsigned &StructuredIndex) {
1621   const ArrayType *arrayType = SemaRef.Context.getAsArrayType(DeclType);
1622
1623   // Check for the special-case of initializing an array with a string.
1624   if (Index < IList->getNumInits()) {
1625     if (IsStringInit(IList->getInit(Index), arrayType, SemaRef.Context) ==
1626         SIF_None) {
1627       // We place the string literal directly into the resulting
1628       // initializer list. This is the only place where the structure
1629       // of the structured initializer list doesn't match exactly,
1630       // because doing so would involve allocating one character
1631       // constant for each string.
1632       if (!VerifyOnly) {
1633         CheckStringInit(IList->getInit(Index), DeclType, arrayType, SemaRef);
1634         UpdateStructuredListElement(StructuredList, StructuredIndex,
1635                                     IList->getInit(Index));
1636         StructuredList->resizeInits(SemaRef.Context, StructuredIndex);
1637       }
1638       ++Index;
1639       return;
1640     }
1641   }
1642   if (const VariableArrayType *VAT = dyn_cast<VariableArrayType>(arrayType)) {
1643     // Check for VLAs; in standard C it would be possible to check this
1644     // earlier, but I don't know where clang accepts VLAs (gcc accepts
1645     // them in all sorts of strange places).
1646     if (!VerifyOnly)
1647       SemaRef.Diag(VAT->getSizeExpr()->getLocStart(),
1648                     diag::err_variable_object_no_init)
1649         << VAT->getSizeExpr()->getSourceRange();
1650     hadError = true;
1651     ++Index;
1652     ++StructuredIndex;
1653     return;
1654   }
1655
1656   // We might know the maximum number of elements in advance.
1657   llvm::APSInt maxElements(elementIndex.getBitWidth(),
1658                            elementIndex.isUnsigned());
1659   bool maxElementsKnown = false;
1660   if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(arrayType)) {
1661     maxElements = CAT->getSize();
1662     elementIndex = elementIndex.extOrTrunc(maxElements.getBitWidth());
1663     elementIndex.setIsUnsigned(maxElements.isUnsigned());
1664     maxElementsKnown = true;
1665   }
1666
1667   QualType elementType = arrayType->getElementType();
1668   while (Index < IList->getNumInits()) {
1669     Expr *Init = IList->getInit(Index);
1670     if (DesignatedInitExpr *DIE = dyn_cast<DesignatedInitExpr>(Init)) {
1671       // If we're not the subobject that matches up with the '{' for
1672       // the designator, we shouldn't be handling the
1673       // designator. Return immediately.
1674       if (!SubobjectIsDesignatorContext)
1675         return;
1676
1677       // Handle this designated initializer. elementIndex will be
1678       // updated to be the next array element we'll initialize.
1679       if (CheckDesignatedInitializer(Entity, IList, DIE, 0,
1680                                      DeclType, nullptr, &elementIndex, Index,
1681                                      StructuredList, StructuredIndex, true,
1682                                      false)) {
1683         hadError = true;
1684         continue;
1685       }
1686
1687       if (elementIndex.getBitWidth() > maxElements.getBitWidth())
1688         maxElements = maxElements.extend(elementIndex.getBitWidth());
1689       else if (elementIndex.getBitWidth() < maxElements.getBitWidth())
1690         elementIndex = elementIndex.extend(maxElements.getBitWidth());
1691       elementIndex.setIsUnsigned(maxElements.isUnsigned());
1692
1693       // If the array is of incomplete type, keep track of the number of
1694       // elements in the initializer.
1695       if (!maxElementsKnown && elementIndex > maxElements)
1696         maxElements = elementIndex;
1697
1698       continue;
1699     }
1700
1701     // If we know the maximum number of elements, and we've already
1702     // hit it, stop consuming elements in the initializer list.
1703     if (maxElementsKnown && elementIndex == maxElements)
1704       break;
1705
1706     InitializedEntity ElementEntity =
1707       InitializedEntity::InitializeElement(SemaRef.Context, StructuredIndex,
1708                                            Entity);
1709     // Check this element.
1710     CheckSubElementType(ElementEntity, IList, elementType, Index,
1711                         StructuredList, StructuredIndex);
1712     ++elementIndex;
1713
1714     // If the array is of incomplete type, keep track of the number of
1715     // elements in the initializer.
1716     if (!maxElementsKnown && elementIndex > maxElements)
1717       maxElements = elementIndex;
1718   }
1719   if (!hadError && DeclType->isIncompleteArrayType() && !VerifyOnly) {
1720     // If this is an incomplete array type, the actual type needs to
1721     // be calculated here.
1722     llvm::APSInt Zero(maxElements.getBitWidth(), maxElements.isUnsigned());
1723     if (maxElements == Zero && !Entity.isVariableLengthArrayNew()) {
1724       // Sizing an array implicitly to zero is not allowed by ISO C,
1725       // but is supported by GNU.
1726       SemaRef.Diag(IList->getLocStart(),
1727                     diag::ext_typecheck_zero_array_size);
1728     }
1729
1730     DeclType = SemaRef.Context.getConstantArrayType(elementType, maxElements,
1731                                                      ArrayType::Normal, 0);
1732   }
1733   if (!hadError && VerifyOnly) {
1734     // If there are any members of the array that get value-initialized, check
1735     // that is possible. That happens if we know the bound and don't have
1736     // enough elements, or if we're performing an array new with an unknown
1737     // bound.
1738     // FIXME: This needs to detect holes left by designated initializers too.
1739     if ((maxElementsKnown && elementIndex < maxElements) ||
1740         Entity.isVariableLengthArrayNew())
1741       CheckEmptyInitializable(InitializedEntity::InitializeElement(
1742                                                   SemaRef.Context, 0, Entity),
1743                               IList->getLocEnd());
1744   }
1745 }
1746
1747 bool InitListChecker::CheckFlexibleArrayInit(const InitializedEntity &Entity,
1748                                              Expr *InitExpr,
1749                                              FieldDecl *Field,
1750                                              bool TopLevelObject) {
1751   // Handle GNU flexible array initializers.
1752   unsigned FlexArrayDiag;
1753   if (isa<InitListExpr>(InitExpr) &&
1754       cast<InitListExpr>(InitExpr)->getNumInits() == 0) {
1755     // Empty flexible array init always allowed as an extension
1756     FlexArrayDiag = diag::ext_flexible_array_init;
1757   } else if (SemaRef.getLangOpts().CPlusPlus) {
1758     // Disallow flexible array init in C++; it is not required for gcc
1759     // compatibility, and it needs work to IRGen correctly in general.
1760     FlexArrayDiag = diag::err_flexible_array_init;
1761   } else if (!TopLevelObject) {
1762     // Disallow flexible array init on non-top-level object
1763     FlexArrayDiag = diag::err_flexible_array_init;
1764   } else if (Entity.getKind() != InitializedEntity::EK_Variable) {
1765     // Disallow flexible array init on anything which is not a variable.
1766     FlexArrayDiag = diag::err_flexible_array_init;
1767   } else if (cast<VarDecl>(Entity.getDecl())->hasLocalStorage()) {
1768     // Disallow flexible array init on local variables.
1769     FlexArrayDiag = diag::err_flexible_array_init;
1770   } else {
1771     // Allow other cases.
1772     FlexArrayDiag = diag::ext_flexible_array_init;
1773   }
1774
1775   if (!VerifyOnly) {
1776     SemaRef.Diag(InitExpr->getLocStart(),
1777                  FlexArrayDiag)
1778       << InitExpr->getLocStart();
1779     SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
1780       << Field;
1781   }
1782
1783   return FlexArrayDiag != diag::ext_flexible_array_init;
1784 }
1785
1786 void InitListChecker::CheckStructUnionTypes(
1787     const InitializedEntity &Entity, InitListExpr *IList, QualType DeclType,
1788     CXXRecordDecl::base_class_range Bases, RecordDecl::field_iterator Field,
1789     bool SubobjectIsDesignatorContext, unsigned &Index,
1790     InitListExpr *StructuredList, unsigned &StructuredIndex,
1791     bool TopLevelObject) {
1792   RecordDecl *structDecl = DeclType->getAs<RecordType>()->getDecl();
1793
1794   // If the record is invalid, some of it's members are invalid. To avoid
1795   // confusion, we forgo checking the intializer for the entire record.
1796   if (structDecl->isInvalidDecl()) {
1797     // Assume it was supposed to consume a single initializer.
1798     ++Index;
1799     hadError = true;
1800     return;
1801   }
1802
1803   if (DeclType->isUnionType() && IList->getNumInits() == 0) {
1804     RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
1805
1806     // If there's a default initializer, use it.
1807     if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->hasInClassInitializer()) {
1808       if (VerifyOnly)
1809         return;
1810       for (RecordDecl::field_iterator FieldEnd = RD->field_end();
1811            Field != FieldEnd; ++Field) {
1812         if (Field->hasInClassInitializer()) {
1813           StructuredList->setInitializedFieldInUnion(*Field);
1814           // FIXME: Actually build a CXXDefaultInitExpr?
1815           return;
1816         }
1817       }
1818     }
1819
1820     // Value-initialize the first member of the union that isn't an unnamed
1821     // bitfield.
1822     for (RecordDecl::field_iterator FieldEnd = RD->field_end();
1823          Field != FieldEnd; ++Field) {
1824       if (!Field->isUnnamedBitfield()) {
1825         if (VerifyOnly)
1826           CheckEmptyInitializable(
1827               InitializedEntity::InitializeMember(*Field, &Entity),
1828               IList->getLocEnd());
1829         else
1830           StructuredList->setInitializedFieldInUnion(*Field);
1831         break;
1832       }
1833     }
1834     return;
1835   }
1836
1837   bool InitializedSomething = false;
1838
1839   // If we have any base classes, they are initialized prior to the fields.
1840   for (auto &Base : Bases) {
1841     Expr *Init = Index < IList->getNumInits() ? IList->getInit(Index) : nullptr;
1842     SourceLocation InitLoc = Init ? Init->getLocStart() : IList->getLocEnd();
1843
1844     // Designated inits always initialize fields, so if we see one, all
1845     // remaining base classes have no explicit initializer.
1846     if (Init && isa<DesignatedInitExpr>(Init))
1847       Init = nullptr;
1848
1849     InitializedEntity BaseEntity = InitializedEntity::InitializeBase(
1850         SemaRef.Context, &Base, false, &Entity);
1851     if (Init) {
1852       CheckSubElementType(BaseEntity, IList, Base.getType(), Index,
1853                           StructuredList, StructuredIndex);
1854       InitializedSomething = true;
1855     } else if (VerifyOnly) {
1856       CheckEmptyInitializable(BaseEntity, InitLoc);
1857     }
1858   }
1859
1860   // If structDecl is a forward declaration, this loop won't do
1861   // anything except look at designated initializers; That's okay,
1862   // because an error should get printed out elsewhere. It might be
1863   // worthwhile to skip over the rest of the initializer, though.
1864   RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
1865   RecordDecl::field_iterator FieldEnd = RD->field_end();
1866   bool CheckForMissingFields =
1867     !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts());
1868
1869   while (Index < IList->getNumInits()) {
1870     Expr *Init = IList->getInit(Index);
1871
1872     if (DesignatedInitExpr *DIE = dyn_cast<DesignatedInitExpr>(Init)) {
1873       // If we're not the subobject that matches up with the '{' for
1874       // the designator, we shouldn't be handling the
1875       // designator. Return immediately.
1876       if (!SubobjectIsDesignatorContext)
1877         return;
1878
1879       // Handle this designated initializer. Field will be updated to
1880       // the next field that we'll be initializing.
1881       if (CheckDesignatedInitializer(Entity, IList, DIE, 0,
1882                                      DeclType, &Field, nullptr, Index,
1883                                      StructuredList, StructuredIndex,
1884                                      true, TopLevelObject))
1885         hadError = true;
1886
1887       InitializedSomething = true;
1888
1889       // Disable check for missing fields when designators are used.
1890       // This matches gcc behaviour.
1891       CheckForMissingFields = false;
1892       continue;
1893     }
1894
1895     if (Field == FieldEnd) {
1896       // We've run out of fields. We're done.
1897       break;
1898     }
1899
1900     // We've already initialized a member of a union. We're done.
1901     if (InitializedSomething && DeclType->isUnionType())
1902       break;
1903
1904     // If we've hit the flexible array member at the end, we're done.
1905     if (Field->getType()->isIncompleteArrayType())
1906       break;
1907
1908     if (Field->isUnnamedBitfield()) {
1909       // Don't initialize unnamed bitfields, e.g. "int : 20;"
1910       ++Field;
1911       continue;
1912     }
1913
1914     // Make sure we can use this declaration.
1915     bool InvalidUse;
1916     if (VerifyOnly)
1917       InvalidUse = !SemaRef.CanUseDecl(*Field, TreatUnavailableAsInvalid);
1918     else
1919       InvalidUse = SemaRef.DiagnoseUseOfDecl(*Field,
1920                                           IList->getInit(Index)->getLocStart());
1921     if (InvalidUse) {
1922       ++Index;
1923       ++Field;
1924       hadError = true;
1925       continue;
1926     }
1927
1928     InitializedEntity MemberEntity =
1929       InitializedEntity::InitializeMember(*Field, &Entity);
1930     CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
1931                         StructuredList, StructuredIndex);
1932     InitializedSomething = true;
1933
1934     if (DeclType->isUnionType() && !VerifyOnly) {
1935       // Initialize the first field within the union.
1936       StructuredList->setInitializedFieldInUnion(*Field);
1937     }
1938
1939     ++Field;
1940   }
1941
1942   // Emit warnings for missing struct field initializers.
1943   if (!VerifyOnly && InitializedSomething && CheckForMissingFields &&
1944       Field != FieldEnd && !Field->getType()->isIncompleteArrayType() &&
1945       !DeclType->isUnionType()) {
1946     // It is possible we have one or more unnamed bitfields remaining.
1947     // Find first (if any) named field and emit warning.
1948     for (RecordDecl::field_iterator it = Field, end = RD->field_end();
1949          it != end; ++it) {
1950       if (!it->isUnnamedBitfield() && !it->hasInClassInitializer()) {
1951         SemaRef.Diag(IList->getSourceRange().getEnd(),
1952                      diag::warn_missing_field_initializers) << *it;
1953         break;
1954       }
1955     }
1956   }
1957
1958   // Check that any remaining fields can be value-initialized.
1959   if (VerifyOnly && Field != FieldEnd && !DeclType->isUnionType() &&
1960       !Field->getType()->isIncompleteArrayType()) {
1961     // FIXME: Should check for holes left by designated initializers too.
1962     for (; Field != FieldEnd && !hadError; ++Field) {
1963       if (!Field->isUnnamedBitfield() && !Field->hasInClassInitializer())
1964         CheckEmptyInitializable(
1965             InitializedEntity::InitializeMember(*Field, &Entity),
1966             IList->getLocEnd());
1967     }
1968   }
1969
1970   if (Field == FieldEnd || !Field->getType()->isIncompleteArrayType() ||
1971       Index >= IList->getNumInits())
1972     return;
1973
1974   if (CheckFlexibleArrayInit(Entity, IList->getInit(Index), *Field,
1975                              TopLevelObject)) {
1976     hadError = true;
1977     ++Index;
1978     return;
1979   }
1980
1981   InitializedEntity MemberEntity =
1982     InitializedEntity::InitializeMember(*Field, &Entity);
1983
1984   if (isa<InitListExpr>(IList->getInit(Index)))
1985     CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
1986                         StructuredList, StructuredIndex);
1987   else
1988     CheckImplicitInitList(MemberEntity, IList, Field->getType(), Index,
1989                           StructuredList, StructuredIndex);
1990 }
1991
1992 /// \brief Expand a field designator that refers to a member of an
1993 /// anonymous struct or union into a series of field designators that
1994 /// refers to the field within the appropriate subobject.
1995 ///
1996 static void ExpandAnonymousFieldDesignator(Sema &SemaRef,
1997                                            DesignatedInitExpr *DIE,
1998                                            unsigned DesigIdx,
1999                                            IndirectFieldDecl *IndirectField) {
2000   typedef DesignatedInitExpr::Designator Designator;
2001
2002   // Build the replacement designators.
2003   SmallVector<Designator, 4> Replacements;
2004   for (IndirectFieldDecl::chain_iterator PI = IndirectField->chain_begin(),
2005        PE = IndirectField->chain_end(); PI != PE; ++PI) {
2006     if (PI + 1 == PE)
2007       Replacements.push_back(Designator((IdentifierInfo *)nullptr,
2008                                     DIE->getDesignator(DesigIdx)->getDotLoc(),
2009                                 DIE->getDesignator(DesigIdx)->getFieldLoc()));
2010     else
2011       Replacements.push_back(Designator((IdentifierInfo *)nullptr,
2012                                         SourceLocation(), SourceLocation()));
2013     assert(isa<FieldDecl>(*PI));
2014     Replacements.back().setField(cast<FieldDecl>(*PI));
2015   }
2016
2017   // Expand the current designator into the set of replacement
2018   // designators, so we have a full subobject path down to where the
2019   // member of the anonymous struct/union is actually stored.
2020   DIE->ExpandDesignator(SemaRef.Context, DesigIdx, &Replacements[0],
2021                         &Replacements[0] + Replacements.size());
2022 }
2023
2024 static DesignatedInitExpr *CloneDesignatedInitExpr(Sema &SemaRef,
2025                                                    DesignatedInitExpr *DIE) {
2026   unsigned NumIndexExprs = DIE->getNumSubExprs() - 1;
2027   SmallVector<Expr*, 4> IndexExprs(NumIndexExprs);
2028   for (unsigned I = 0; I < NumIndexExprs; ++I)
2029     IndexExprs[I] = DIE->getSubExpr(I + 1);
2030   return DesignatedInitExpr::Create(SemaRef.Context, DIE->designators(),
2031                                     IndexExprs,
2032                                     DIE->getEqualOrColonLoc(),
2033                                     DIE->usesGNUSyntax(), DIE->getInit());
2034 }
2035
2036 namespace {
2037
2038 // Callback to only accept typo corrections that are for field members of
2039 // the given struct or union.
2040 class FieldInitializerValidatorCCC : public CorrectionCandidateCallback {
2041  public:
2042   explicit FieldInitializerValidatorCCC(RecordDecl *RD)
2043       : Record(RD) {}
2044
2045   bool ValidateCandidate(const TypoCorrection &candidate) override {
2046     FieldDecl *FD = candidate.getCorrectionDeclAs<FieldDecl>();
2047     return FD && FD->getDeclContext()->getRedeclContext()->Equals(Record);
2048   }
2049
2050  private:
2051   RecordDecl *Record;
2052 };
2053
2054 } // end anonymous namespace
2055
2056 /// @brief Check the well-formedness of a C99 designated initializer.
2057 ///
2058 /// Determines whether the designated initializer @p DIE, which
2059 /// resides at the given @p Index within the initializer list @p
2060 /// IList, is well-formed for a current object of type @p DeclType
2061 /// (C99 6.7.8). The actual subobject that this designator refers to
2062 /// within the current subobject is returned in either
2063 /// @p NextField or @p NextElementIndex (whichever is appropriate).
2064 ///
2065 /// @param IList  The initializer list in which this designated
2066 /// initializer occurs.
2067 ///
2068 /// @param DIE The designated initializer expression.
2069 ///
2070 /// @param DesigIdx  The index of the current designator.
2071 ///
2072 /// @param CurrentObjectType The type of the "current object" (C99 6.7.8p17),
2073 /// into which the designation in @p DIE should refer.
2074 ///
2075 /// @param NextField  If non-NULL and the first designator in @p DIE is
2076 /// a field, this will be set to the field declaration corresponding
2077 /// to the field named by the designator.
2078 ///
2079 /// @param NextElementIndex  If non-NULL and the first designator in @p
2080 /// DIE is an array designator or GNU array-range designator, this
2081 /// will be set to the last index initialized by this designator.
2082 ///
2083 /// @param Index  Index into @p IList where the designated initializer
2084 /// @p DIE occurs.
2085 ///
2086 /// @param StructuredList  The initializer list expression that
2087 /// describes all of the subobject initializers in the order they'll
2088 /// actually be initialized.
2089 ///
2090 /// @returns true if there was an error, false otherwise.
2091 bool
2092 InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
2093                                             InitListExpr *IList,
2094                                             DesignatedInitExpr *DIE,
2095                                             unsigned DesigIdx,
2096                                             QualType &CurrentObjectType,
2097                                           RecordDecl::field_iterator *NextField,
2098                                             llvm::APSInt *NextElementIndex,
2099                                             unsigned &Index,
2100                                             InitListExpr *StructuredList,
2101                                             unsigned &StructuredIndex,
2102                                             bool FinishSubobjectInit,
2103                                             bool TopLevelObject) {
2104   if (DesigIdx == DIE->size()) {
2105     // Check the actual initialization for the designated object type.
2106     bool prevHadError = hadError;
2107
2108     // Temporarily remove the designator expression from the
2109     // initializer list that the child calls see, so that we don't try
2110     // to re-process the designator.
2111     unsigned OldIndex = Index;
2112     IList->setInit(OldIndex, DIE->getInit());
2113
2114     CheckSubElementType(Entity, IList, CurrentObjectType, Index,
2115                         StructuredList, StructuredIndex);
2116
2117     // Restore the designated initializer expression in the syntactic
2118     // form of the initializer list.
2119     if (IList->getInit(OldIndex) != DIE->getInit())
2120       DIE->setInit(IList->getInit(OldIndex));
2121     IList->setInit(OldIndex, DIE);
2122
2123     return hadError && !prevHadError;
2124   }
2125
2126   DesignatedInitExpr::Designator *D = DIE->getDesignator(DesigIdx);
2127   bool IsFirstDesignator = (DesigIdx == 0);
2128   if (!VerifyOnly) {
2129     assert((IsFirstDesignator || StructuredList) &&
2130            "Need a non-designated initializer list to start from");
2131
2132     // Determine the structural initializer list that corresponds to the
2133     // current subobject.
2134     if (IsFirstDesignator)
2135       StructuredList = SyntacticToSemantic.lookup(IList);
2136     else {
2137       Expr *ExistingInit = StructuredIndex < StructuredList->getNumInits() ?
2138           StructuredList->getInit(StructuredIndex) : nullptr;
2139       if (!ExistingInit && StructuredList->hasArrayFiller())
2140         ExistingInit = StructuredList->getArrayFiller();
2141
2142       if (!ExistingInit)
2143         StructuredList =
2144           getStructuredSubobjectInit(IList, Index, CurrentObjectType,
2145                                      StructuredList, StructuredIndex,
2146                                      SourceRange(D->getLocStart(),
2147                                                  DIE->getLocEnd()));
2148       else if (InitListExpr *Result = dyn_cast<InitListExpr>(ExistingInit))
2149         StructuredList = Result;
2150       else {
2151         if (DesignatedInitUpdateExpr *E =
2152                 dyn_cast<DesignatedInitUpdateExpr>(ExistingInit))
2153           StructuredList = E->getUpdater();
2154         else {
2155           DesignatedInitUpdateExpr *DIUE =
2156               new (SemaRef.Context) DesignatedInitUpdateExpr(SemaRef.Context,
2157                                         D->getLocStart(), ExistingInit,
2158                                         DIE->getLocEnd());
2159           StructuredList->updateInit(SemaRef.Context, StructuredIndex, DIUE);
2160           StructuredList = DIUE->getUpdater();
2161         }
2162
2163         // We need to check on source range validity because the previous
2164         // initializer does not have to be an explicit initializer. e.g.,
2165         //
2166         // struct P { int a, b; };
2167         // struct PP { struct P p } l = { { .a = 2 }, .p.b = 3 };
2168         //
2169         // There is an overwrite taking place because the first braced initializer
2170         // list "{ .a = 2 }" already provides value for .p.b (which is zero).
2171         if (ExistingInit->getSourceRange().isValid()) {
2172           // We are creating an initializer list that initializes the
2173           // subobjects of the current object, but there was already an
2174           // initialization that completely initialized the current
2175           // subobject, e.g., by a compound literal:
2176           //
2177           // struct X { int a, b; };
2178           // struct X xs[] = { [0] = (struct X) { 1, 2 }, [0].b = 3 };
2179           //
2180           // Here, xs[0].a == 0 and xs[0].b == 3, since the second,
2181           // designated initializer re-initializes the whole
2182           // subobject [0], overwriting previous initializers.
2183           SemaRef.Diag(D->getLocStart(),
2184                        diag::warn_subobject_initializer_overrides)
2185             << SourceRange(D->getLocStart(), DIE->getLocEnd());
2186
2187           SemaRef.Diag(ExistingInit->getLocStart(),
2188                        diag::note_previous_initializer)
2189             << /*FIXME:has side effects=*/0
2190             << ExistingInit->getSourceRange();
2191         }
2192       }
2193     }
2194     assert(StructuredList && "Expected a structured initializer list");
2195   }
2196
2197   if (D->isFieldDesignator()) {
2198     // C99 6.7.8p7:
2199     //
2200     //   If a designator has the form
2201     //
2202     //      . identifier
2203     //
2204     //   then the current object (defined below) shall have
2205     //   structure or union type and the identifier shall be the
2206     //   name of a member of that type.
2207     const RecordType *RT = CurrentObjectType->getAs<RecordType>();
2208     if (!RT) {
2209       SourceLocation Loc = D->getDotLoc();
2210       if (Loc.isInvalid())
2211         Loc = D->getFieldLoc();
2212       if (!VerifyOnly)
2213         SemaRef.Diag(Loc, diag::err_field_designator_non_aggr)
2214           << SemaRef.getLangOpts().CPlusPlus << CurrentObjectType;
2215       ++Index;
2216       return true;
2217     }
2218
2219     FieldDecl *KnownField = D->getField();
2220     if (!KnownField) {
2221       IdentifierInfo *FieldName = D->getFieldName();
2222       DeclContext::lookup_result Lookup = RT->getDecl()->lookup(FieldName);
2223       for (NamedDecl *ND : Lookup) {
2224         if (auto *FD = dyn_cast<FieldDecl>(ND)) {
2225           KnownField = FD;
2226           break;
2227         }
2228         if (auto *IFD = dyn_cast<IndirectFieldDecl>(ND)) {
2229           // In verify mode, don't modify the original.
2230           if (VerifyOnly)
2231             DIE = CloneDesignatedInitExpr(SemaRef, DIE);
2232           ExpandAnonymousFieldDesignator(SemaRef, DIE, DesigIdx, IFD);
2233           D = DIE->getDesignator(DesigIdx);
2234           KnownField = cast<FieldDecl>(*IFD->chain_begin());
2235           break;
2236         }
2237       }
2238       if (!KnownField) {
2239         if (VerifyOnly) {
2240           ++Index;
2241           return true;  // No typo correction when just trying this out.
2242         }
2243
2244         // Name lookup found something, but it wasn't a field.
2245         if (!Lookup.empty()) {
2246           SemaRef.Diag(D->getFieldLoc(), diag::err_field_designator_nonfield)
2247             << FieldName;
2248           SemaRef.Diag(Lookup.front()->getLocation(),
2249                        diag::note_field_designator_found);
2250           ++Index;
2251           return true;
2252         }
2253
2254         // Name lookup didn't find anything.
2255         // Determine whether this was a typo for another field name.
2256         if (TypoCorrection Corrected = SemaRef.CorrectTypo(
2257                 DeclarationNameInfo(FieldName, D->getFieldLoc()),
2258                 Sema::LookupMemberName, /*Scope=*/nullptr, /*SS=*/nullptr,
2259                 llvm::make_unique<FieldInitializerValidatorCCC>(RT->getDecl()),
2260                 Sema::CTK_ErrorRecovery, RT->getDecl())) {
2261           SemaRef.diagnoseTypo(
2262               Corrected,
2263               SemaRef.PDiag(diag::err_field_designator_unknown_suggest)
2264                 << FieldName << CurrentObjectType);
2265           KnownField = Corrected.getCorrectionDeclAs<FieldDecl>();
2266           hadError = true;
2267         } else {
2268           // Typo correction didn't find anything.
2269           SemaRef.Diag(D->getFieldLoc(), diag::err_field_designator_unknown)
2270             << FieldName << CurrentObjectType;
2271           ++Index;
2272           return true;
2273         }
2274       }
2275     }
2276
2277     unsigned FieldIndex = 0;
2278
2279     if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
2280       FieldIndex = CXXRD->getNumBases();
2281
2282     for (auto *FI : RT->getDecl()->fields()) {
2283       if (FI->isUnnamedBitfield())
2284         continue;
2285       if (declaresSameEntity(KnownField, FI)) {
2286         KnownField = FI;
2287         break;
2288       }
2289       ++FieldIndex;
2290     }
2291
2292     RecordDecl::field_iterator Field =
2293         RecordDecl::field_iterator(DeclContext::decl_iterator(KnownField));
2294
2295     // All of the fields of a union are located at the same place in
2296     // the initializer list.
2297     if (RT->getDecl()->isUnion()) {
2298       FieldIndex = 0;
2299       if (!VerifyOnly) {
2300         FieldDecl *CurrentField = StructuredList->getInitializedFieldInUnion();
2301         if (CurrentField && !declaresSameEntity(CurrentField, *Field)) {
2302           assert(StructuredList->getNumInits() == 1
2303                  && "A union should never have more than one initializer!");
2304
2305           Expr *ExistingInit = StructuredList->getInit(0);
2306           if (ExistingInit) {
2307             // We're about to throw away an initializer, emit warning.
2308             SemaRef.Diag(D->getFieldLoc(),
2309                          diag::warn_initializer_overrides)
2310               << D->getSourceRange();
2311             SemaRef.Diag(ExistingInit->getLocStart(),
2312                          diag::note_previous_initializer)
2313               << /*FIXME:has side effects=*/0
2314               << ExistingInit->getSourceRange();
2315           }
2316
2317           // remove existing initializer
2318           StructuredList->resizeInits(SemaRef.Context, 0);
2319           StructuredList->setInitializedFieldInUnion(nullptr);
2320         }
2321
2322         StructuredList->setInitializedFieldInUnion(*Field);
2323       }
2324     }
2325
2326     // Make sure we can use this declaration.
2327     bool InvalidUse;
2328     if (VerifyOnly)
2329       InvalidUse = !SemaRef.CanUseDecl(*Field, TreatUnavailableAsInvalid);
2330     else
2331       InvalidUse = SemaRef.DiagnoseUseOfDecl(*Field, D->getFieldLoc());
2332     if (InvalidUse) {
2333       ++Index;
2334       return true;
2335     }
2336
2337     if (!VerifyOnly) {
2338       // Update the designator with the field declaration.
2339       D->setField(*Field);
2340
2341       // Make sure that our non-designated initializer list has space
2342       // for a subobject corresponding to this field.
2343       if (FieldIndex >= StructuredList->getNumInits())
2344         StructuredList->resizeInits(SemaRef.Context, FieldIndex + 1);
2345     }
2346
2347     // This designator names a flexible array member.
2348     if (Field->getType()->isIncompleteArrayType()) {
2349       bool Invalid = false;
2350       if ((DesigIdx + 1) != DIE->size()) {
2351         // We can't designate an object within the flexible array
2352         // member (because GCC doesn't allow it).
2353         if (!VerifyOnly) {
2354           DesignatedInitExpr::Designator *NextD
2355             = DIE->getDesignator(DesigIdx + 1);
2356           SemaRef.Diag(NextD->getLocStart(),
2357                         diag::err_designator_into_flexible_array_member)
2358             << SourceRange(NextD->getLocStart(),
2359                            DIE->getLocEnd());
2360           SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
2361             << *Field;
2362         }
2363         Invalid = true;
2364       }
2365
2366       if (!hadError && !isa<InitListExpr>(DIE->getInit()) &&
2367           !isa<StringLiteral>(DIE->getInit())) {
2368         // The initializer is not an initializer list.
2369         if (!VerifyOnly) {
2370           SemaRef.Diag(DIE->getInit()->getLocStart(),
2371                         diag::err_flexible_array_init_needs_braces)
2372             << DIE->getInit()->getSourceRange();
2373           SemaRef.Diag(Field->getLocation(), diag::note_flexible_array_member)
2374             << *Field;
2375         }
2376         Invalid = true;
2377       }
2378
2379       // Check GNU flexible array initializer.
2380       if (!Invalid && CheckFlexibleArrayInit(Entity, DIE->getInit(), *Field,
2381                                              TopLevelObject))
2382         Invalid = true;
2383
2384       if (Invalid) {
2385         ++Index;
2386         return true;
2387       }
2388
2389       // Initialize the array.
2390       bool prevHadError = hadError;
2391       unsigned newStructuredIndex = FieldIndex;
2392       unsigned OldIndex = Index;
2393       IList->setInit(Index, DIE->getInit());
2394
2395       InitializedEntity MemberEntity =
2396         InitializedEntity::InitializeMember(*Field, &Entity);
2397       CheckSubElementType(MemberEntity, IList, Field->getType(), Index,
2398                           StructuredList, newStructuredIndex);
2399
2400       IList->setInit(OldIndex, DIE);
2401       if (hadError && !prevHadError) {
2402         ++Field;
2403         ++FieldIndex;
2404         if (NextField)
2405           *NextField = Field;
2406         StructuredIndex = FieldIndex;
2407         return true;
2408       }
2409     } else {
2410       // Recurse to check later designated subobjects.
2411       QualType FieldType = Field->getType();
2412       unsigned newStructuredIndex = FieldIndex;
2413
2414       InitializedEntity MemberEntity =
2415         InitializedEntity::InitializeMember(*Field, &Entity);
2416       if (CheckDesignatedInitializer(MemberEntity, IList, DIE, DesigIdx + 1,
2417                                      FieldType, nullptr, nullptr, Index,
2418                                      StructuredList, newStructuredIndex,
2419                                      FinishSubobjectInit, false))
2420         return true;
2421     }
2422
2423     // Find the position of the next field to be initialized in this
2424     // subobject.
2425     ++Field;
2426     ++FieldIndex;
2427
2428     // If this the first designator, our caller will continue checking
2429     // the rest of this struct/class/union subobject.
2430     if (IsFirstDesignator) {
2431       if (NextField)
2432         *NextField = Field;
2433       StructuredIndex = FieldIndex;
2434       return false;
2435     }
2436
2437     if (!FinishSubobjectInit)
2438       return false;
2439
2440     // We've already initialized something in the union; we're done.
2441     if (RT->getDecl()->isUnion())
2442       return hadError;
2443
2444     // Check the remaining fields within this class/struct/union subobject.
2445     bool prevHadError = hadError;
2446
2447     auto NoBases =
2448         CXXRecordDecl::base_class_range(CXXRecordDecl::base_class_iterator(),
2449                                         CXXRecordDecl::base_class_iterator());
2450     CheckStructUnionTypes(Entity, IList, CurrentObjectType, NoBases, Field,
2451                           false, Index, StructuredList, FieldIndex);
2452     return hadError && !prevHadError;
2453   }
2454
2455   // C99 6.7.8p6:
2456   //
2457   //   If a designator has the form
2458   //
2459   //      [ constant-expression ]
2460   //
2461   //   then the current object (defined below) shall have array
2462   //   type and the expression shall be an integer constant
2463   //   expression. If the array is of unknown size, any
2464   //   nonnegative value is valid.
2465   //
2466   // Additionally, cope with the GNU extension that permits
2467   // designators of the form
2468   //
2469   //      [ constant-expression ... constant-expression ]
2470   const ArrayType *AT = SemaRef.Context.getAsArrayType(CurrentObjectType);
2471   if (!AT) {
2472     if (!VerifyOnly)
2473       SemaRef.Diag(D->getLBracketLoc(), diag::err_array_designator_non_array)
2474         << CurrentObjectType;
2475     ++Index;
2476     return true;
2477   }
2478
2479   Expr *IndexExpr = nullptr;
2480   llvm::APSInt DesignatedStartIndex, DesignatedEndIndex;
2481   if (D->isArrayDesignator()) {
2482     IndexExpr = DIE->getArrayIndex(*D);
2483     DesignatedStartIndex = IndexExpr->EvaluateKnownConstInt(SemaRef.Context);
2484     DesignatedEndIndex = DesignatedStartIndex;
2485   } else {
2486     assert(D->isArrayRangeDesignator() && "Need array-range designator");
2487
2488     DesignatedStartIndex =
2489       DIE->getArrayRangeStart(*D)->EvaluateKnownConstInt(SemaRef.Context);
2490     DesignatedEndIndex =
2491       DIE->getArrayRangeEnd(*D)->EvaluateKnownConstInt(SemaRef.Context);
2492     IndexExpr = DIE->getArrayRangeEnd(*D);
2493
2494     // Codegen can't handle evaluating array range designators that have side
2495     // effects, because we replicate the AST value for each initialized element.
2496     // As such, set the sawArrayRangeDesignator() bit if we initialize multiple
2497     // elements with something that has a side effect, so codegen can emit an
2498     // "error unsupported" error instead of miscompiling the app.
2499     if (DesignatedStartIndex.getZExtValue()!=DesignatedEndIndex.getZExtValue()&&
2500         DIE->getInit()->HasSideEffects(SemaRef.Context) && !VerifyOnly)
2501       FullyStructuredList->sawArrayRangeDesignator();
2502   }
2503
2504   if (isa<ConstantArrayType>(AT)) {
2505     llvm::APSInt MaxElements(cast<ConstantArrayType>(AT)->getSize(), false);
2506     DesignatedStartIndex
2507       = DesignatedStartIndex.extOrTrunc(MaxElements.getBitWidth());
2508     DesignatedStartIndex.setIsUnsigned(MaxElements.isUnsigned());
2509     DesignatedEndIndex
2510       = DesignatedEndIndex.extOrTrunc(MaxElements.getBitWidth());
2511     DesignatedEndIndex.setIsUnsigned(MaxElements.isUnsigned());
2512     if (DesignatedEndIndex >= MaxElements) {
2513       if (!VerifyOnly)
2514         SemaRef.Diag(IndexExpr->getLocStart(),
2515                       diag::err_array_designator_too_large)
2516           << DesignatedEndIndex.toString(10) << MaxElements.toString(10)
2517           << IndexExpr->getSourceRange();
2518       ++Index;
2519       return true;
2520     }
2521   } else {
2522     unsigned DesignatedIndexBitWidth =
2523       ConstantArrayType::getMaxSizeBits(SemaRef.Context);
2524     DesignatedStartIndex =
2525       DesignatedStartIndex.extOrTrunc(DesignatedIndexBitWidth);
2526     DesignatedEndIndex =
2527       DesignatedEndIndex.extOrTrunc(DesignatedIndexBitWidth);
2528     DesignatedStartIndex.setIsUnsigned(true);
2529     DesignatedEndIndex.setIsUnsigned(true);
2530   }
2531
2532   if (!VerifyOnly && StructuredList->isStringLiteralInit()) {
2533     // We're modifying a string literal init; we have to decompose the string
2534     // so we can modify the individual characters.
2535     ASTContext &Context = SemaRef.Context;
2536     Expr *SubExpr = StructuredList->getInit(0)->IgnoreParens();
2537
2538     // Compute the character type
2539     QualType CharTy = AT->getElementType();
2540
2541     // Compute the type of the integer literals.
2542     QualType PromotedCharTy = CharTy;
2543     if (CharTy->isPromotableIntegerType())
2544       PromotedCharTy = Context.getPromotedIntegerType(CharTy);
2545     unsigned PromotedCharTyWidth = Context.getTypeSize(PromotedCharTy);
2546
2547     if (StringLiteral *SL = dyn_cast<StringLiteral>(SubExpr)) {
2548       // Get the length of the string.
2549       uint64_t StrLen = SL->getLength();
2550       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
2551         StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
2552       StructuredList->resizeInits(Context, StrLen);
2553
2554       // Build a literal for each character in the string, and put them into
2555       // the init list.
2556       for (unsigned i = 0, e = StrLen; i != e; ++i) {
2557         llvm::APInt CodeUnit(PromotedCharTyWidth, SL->getCodeUnit(i));
2558         Expr *Init = new (Context) IntegerLiteral(
2559             Context, CodeUnit, PromotedCharTy, SubExpr->getExprLoc());
2560         if (CharTy != PromotedCharTy)
2561           Init = ImplicitCastExpr::Create(Context, CharTy, CK_IntegralCast,
2562                                           Init, nullptr, VK_RValue);
2563         StructuredList->updateInit(Context, i, Init);
2564       }
2565     } else {
2566       ObjCEncodeExpr *E = cast<ObjCEncodeExpr>(SubExpr);
2567       std::string Str;
2568       Context.getObjCEncodingForType(E->getEncodedType(), Str);
2569
2570       // Get the length of the string.
2571       uint64_t StrLen = Str.size();
2572       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
2573         StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
2574       StructuredList->resizeInits(Context, StrLen);
2575
2576       // Build a literal for each character in the string, and put them into
2577       // the init list.
2578       for (unsigned i = 0, e = StrLen; i != e; ++i) {
2579         llvm::APInt CodeUnit(PromotedCharTyWidth, Str[i]);
2580         Expr *Init = new (Context) IntegerLiteral(
2581             Context, CodeUnit, PromotedCharTy, SubExpr->getExprLoc());
2582         if (CharTy != PromotedCharTy)
2583           Init = ImplicitCastExpr::Create(Context, CharTy, CK_IntegralCast,
2584                                           Init, nullptr, VK_RValue);
2585         StructuredList->updateInit(Context, i, Init);
2586       }
2587     }
2588   }
2589
2590   // Make sure that our non-designated initializer list has space
2591   // for a subobject corresponding to this array element.
2592   if (!VerifyOnly &&
2593       DesignatedEndIndex.getZExtValue() >= StructuredList->getNumInits())
2594     StructuredList->resizeInits(SemaRef.Context,
2595                                 DesignatedEndIndex.getZExtValue() + 1);
2596
2597   // Repeatedly perform subobject initializations in the range
2598   // [DesignatedStartIndex, DesignatedEndIndex].
2599
2600   // Move to the next designator
2601   unsigned ElementIndex = DesignatedStartIndex.getZExtValue();
2602   unsigned OldIndex = Index;
2603
2604   InitializedEntity ElementEntity =
2605     InitializedEntity::InitializeElement(SemaRef.Context, 0, Entity);
2606
2607   while (DesignatedStartIndex <= DesignatedEndIndex) {
2608     // Recurse to check later designated subobjects.
2609     QualType ElementType = AT->getElementType();
2610     Index = OldIndex;
2611
2612     ElementEntity.setElementIndex(ElementIndex);
2613     if (CheckDesignatedInitializer(
2614             ElementEntity, IList, DIE, DesigIdx + 1, ElementType, nullptr,
2615             nullptr, Index, StructuredList, ElementIndex,
2616             FinishSubobjectInit && (DesignatedStartIndex == DesignatedEndIndex),
2617             false))
2618       return true;
2619
2620     // Move to the next index in the array that we'll be initializing.
2621     ++DesignatedStartIndex;
2622     ElementIndex = DesignatedStartIndex.getZExtValue();
2623   }
2624
2625   // If this the first designator, our caller will continue checking
2626   // the rest of this array subobject.
2627   if (IsFirstDesignator) {
2628     if (NextElementIndex)
2629       *NextElementIndex = DesignatedStartIndex;
2630     StructuredIndex = ElementIndex;
2631     return false;
2632   }
2633
2634   if (!FinishSubobjectInit)
2635     return false;
2636
2637   // Check the remaining elements within this array subobject.
2638   bool prevHadError = hadError;
2639   CheckArrayType(Entity, IList, CurrentObjectType, DesignatedStartIndex,
2640                  /*SubobjectIsDesignatorContext=*/false, Index,
2641                  StructuredList, ElementIndex);
2642   return hadError && !prevHadError;
2643 }
2644
2645 // Get the structured initializer list for a subobject of type
2646 // @p CurrentObjectType.
2647 InitListExpr *
2648 InitListChecker::getStructuredSubobjectInit(InitListExpr *IList, unsigned Index,
2649                                             QualType CurrentObjectType,
2650                                             InitListExpr *StructuredList,
2651                                             unsigned StructuredIndex,
2652                                             SourceRange InitRange,
2653                                             bool IsFullyOverwritten) {
2654   if (VerifyOnly)
2655     return nullptr; // No structured list in verification-only mode.
2656   Expr *ExistingInit = nullptr;
2657   if (!StructuredList)
2658     ExistingInit = SyntacticToSemantic.lookup(IList);
2659   else if (StructuredIndex < StructuredList->getNumInits())
2660     ExistingInit = StructuredList->getInit(StructuredIndex);
2661
2662   if (InitListExpr *Result = dyn_cast_or_null<InitListExpr>(ExistingInit))
2663     // There might have already been initializers for subobjects of the current
2664     // object, but a subsequent initializer list will overwrite the entirety
2665     // of the current object. (See DR 253 and C99 6.7.8p21). e.g.,
2666     //
2667     // struct P { char x[6]; };
2668     // struct P l = { .x[2] = 'x', .x = { [0] = 'f' } };
2669     //
2670     // The first designated initializer is ignored, and l.x is just "f".
2671     if (!IsFullyOverwritten)
2672       return Result;
2673
2674   if (ExistingInit) {
2675     // We are creating an initializer list that initializes the
2676     // subobjects of the current object, but there was already an
2677     // initialization that completely initialized the current
2678     // subobject, e.g., by a compound literal:
2679     //
2680     // struct X { int a, b; };
2681     // struct X xs[] = { [0] = (struct X) { 1, 2 }, [0].b = 3 };
2682     //
2683     // Here, xs[0].a == 0 and xs[0].b == 3, since the second,
2684     // designated initializer re-initializes the whole
2685     // subobject [0], overwriting previous initializers.
2686     SemaRef.Diag(InitRange.getBegin(),
2687                  diag::warn_subobject_initializer_overrides)
2688       << InitRange;
2689     SemaRef.Diag(ExistingInit->getLocStart(),
2690                   diag::note_previous_initializer)
2691       << /*FIXME:has side effects=*/0
2692       << ExistingInit->getSourceRange();
2693   }
2694
2695   InitListExpr *Result
2696     = new (SemaRef.Context) InitListExpr(SemaRef.Context,
2697                                          InitRange.getBegin(), None,
2698                                          InitRange.getEnd());
2699
2700   QualType ResultType = CurrentObjectType;
2701   if (!ResultType->isArrayType())
2702     ResultType = ResultType.getNonLValueExprType(SemaRef.Context);
2703   Result->setType(ResultType);
2704
2705   // Pre-allocate storage for the structured initializer list.
2706   unsigned NumElements = 0;
2707   unsigned NumInits = 0;
2708   bool GotNumInits = false;
2709   if (!StructuredList) {
2710     NumInits = IList->getNumInits();
2711     GotNumInits = true;
2712   } else if (Index < IList->getNumInits()) {
2713     if (InitListExpr *SubList = dyn_cast<InitListExpr>(IList->getInit(Index))) {
2714       NumInits = SubList->getNumInits();
2715       GotNumInits = true;
2716     }
2717   }
2718
2719   if (const ArrayType *AType
2720       = SemaRef.Context.getAsArrayType(CurrentObjectType)) {
2721     if (const ConstantArrayType *CAType = dyn_cast<ConstantArrayType>(AType)) {
2722       NumElements = CAType->getSize().getZExtValue();
2723       // Simple heuristic so that we don't allocate a very large
2724       // initializer with many empty entries at the end.
2725       if (GotNumInits && NumElements > NumInits)
2726         NumElements = 0;
2727     }
2728   } else if (const VectorType *VType = CurrentObjectType->getAs<VectorType>())
2729     NumElements = VType->getNumElements();
2730   else if (const RecordType *RType = CurrentObjectType->getAs<RecordType>()) {
2731     RecordDecl *RDecl = RType->getDecl();
2732     if (RDecl->isUnion())
2733       NumElements = 1;
2734     else
2735       NumElements = std::distance(RDecl->field_begin(), RDecl->field_end());
2736   }
2737
2738   Result->reserveInits(SemaRef.Context, NumElements);
2739
2740   // Link this new initializer list into the structured initializer
2741   // lists.
2742   if (StructuredList)
2743     StructuredList->updateInit(SemaRef.Context, StructuredIndex, Result);
2744   else {
2745     Result->setSyntacticForm(IList);
2746     SyntacticToSemantic[IList] = Result;
2747   }
2748
2749   return Result;
2750 }
2751
2752 /// Update the initializer at index @p StructuredIndex within the
2753 /// structured initializer list to the value @p expr.
2754 void InitListChecker::UpdateStructuredListElement(InitListExpr *StructuredList,
2755                                                   unsigned &StructuredIndex,
2756                                                   Expr *expr) {
2757   // No structured initializer list to update
2758   if (!StructuredList)
2759     return;
2760
2761   if (Expr *PrevInit = StructuredList->updateInit(SemaRef.Context,
2762                                                   StructuredIndex, expr)) {
2763     // This initializer overwrites a previous initializer. Warn.
2764     // We need to check on source range validity because the previous
2765     // initializer does not have to be an explicit initializer.
2766     // struct P { int a, b; };
2767     // struct PP { struct P p } l = { { .a = 2 }, .p.b = 3 };
2768     // There is an overwrite taking place because the first braced initializer
2769     // list "{ .a = 2 }' already provides value for .p.b (which is zero).
2770     if (PrevInit->getSourceRange().isValid()) {
2771       SemaRef.Diag(expr->getLocStart(),
2772                    diag::warn_initializer_overrides)
2773         << expr->getSourceRange();
2774
2775       SemaRef.Diag(PrevInit->getLocStart(),
2776                    diag::note_previous_initializer)
2777         << /*FIXME:has side effects=*/0
2778         << PrevInit->getSourceRange();
2779     }
2780   }
2781
2782   ++StructuredIndex;
2783 }
2784
2785 /// Check that the given Index expression is a valid array designator
2786 /// value. This is essentially just a wrapper around
2787 /// VerifyIntegerConstantExpression that also checks for negative values
2788 /// and produces a reasonable diagnostic if there is a
2789 /// failure. Returns the index expression, possibly with an implicit cast
2790 /// added, on success.  If everything went okay, Value will receive the
2791 /// value of the constant expression.
2792 static ExprResult
2793 CheckArrayDesignatorExpr(Sema &S, Expr *Index, llvm::APSInt &Value) {
2794   SourceLocation Loc = Index->getLocStart();
2795
2796   // Make sure this is an integer constant expression.
2797   ExprResult Result = S.VerifyIntegerConstantExpression(Index, &Value);
2798   if (Result.isInvalid())
2799     return Result;
2800
2801   if (Value.isSigned() && Value.isNegative())
2802     return S.Diag(Loc, diag::err_array_designator_negative)
2803       << Value.toString(10) << Index->getSourceRange();
2804
2805   Value.setIsUnsigned(true);
2806   return Result;
2807 }
2808
2809 ExprResult Sema::ActOnDesignatedInitializer(Designation &Desig,
2810                                             SourceLocation Loc,
2811                                             bool GNUSyntax,
2812                                             ExprResult Init) {
2813   typedef DesignatedInitExpr::Designator ASTDesignator;
2814
2815   bool Invalid = false;
2816   SmallVector<ASTDesignator, 32> Designators;
2817   SmallVector<Expr *, 32> InitExpressions;
2818
2819   // Build designators and check array designator expressions.
2820   for (unsigned Idx = 0; Idx < Desig.getNumDesignators(); ++Idx) {
2821     const Designator &D = Desig.getDesignator(Idx);
2822     switch (D.getKind()) {
2823     case Designator::FieldDesignator:
2824       Designators.push_back(ASTDesignator(D.getField(), D.getDotLoc(),
2825                                           D.getFieldLoc()));
2826       break;
2827
2828     case Designator::ArrayDesignator: {
2829       Expr *Index = static_cast<Expr *>(D.getArrayIndex());
2830       llvm::APSInt IndexValue;
2831       if (!Index->isTypeDependent() && !Index->isValueDependent())
2832         Index = CheckArrayDesignatorExpr(*this, Index, IndexValue).get();
2833       if (!Index)
2834         Invalid = true;
2835       else {
2836         Designators.push_back(ASTDesignator(InitExpressions.size(),
2837                                             D.getLBracketLoc(),
2838                                             D.getRBracketLoc()));
2839         InitExpressions.push_back(Index);
2840       }
2841       break;
2842     }
2843
2844     case Designator::ArrayRangeDesignator: {
2845       Expr *StartIndex = static_cast<Expr *>(D.getArrayRangeStart());
2846       Expr *EndIndex = static_cast<Expr *>(D.getArrayRangeEnd());
2847       llvm::APSInt StartValue;
2848       llvm::APSInt EndValue;
2849       bool StartDependent = StartIndex->isTypeDependent() ||
2850                             StartIndex->isValueDependent();
2851       bool EndDependent = EndIndex->isTypeDependent() ||
2852                           EndIndex->isValueDependent();
2853       if (!StartDependent)
2854         StartIndex =
2855             CheckArrayDesignatorExpr(*this, StartIndex, StartValue).get();
2856       if (!EndDependent)
2857         EndIndex = CheckArrayDesignatorExpr(*this, EndIndex, EndValue).get();
2858
2859       if (!StartIndex || !EndIndex)
2860         Invalid = true;
2861       else {
2862         // Make sure we're comparing values with the same bit width.
2863         if (StartDependent || EndDependent) {
2864           // Nothing to compute.
2865         } else if (StartValue.getBitWidth() > EndValue.getBitWidth())
2866           EndValue = EndValue.extend(StartValue.getBitWidth());
2867         else if (StartValue.getBitWidth() < EndValue.getBitWidth())
2868           StartValue = StartValue.extend(EndValue.getBitWidth());
2869
2870         if (!StartDependent && !EndDependent && EndValue < StartValue) {
2871           Diag(D.getEllipsisLoc(), diag::err_array_designator_empty_range)
2872             << StartValue.toString(10) << EndValue.toString(10)
2873             << StartIndex->getSourceRange() << EndIndex->getSourceRange();
2874           Invalid = true;
2875         } else {
2876           Designators.push_back(ASTDesignator(InitExpressions.size(),
2877                                               D.getLBracketLoc(),
2878                                               D.getEllipsisLoc(),
2879                                               D.getRBracketLoc()));
2880           InitExpressions.push_back(StartIndex);
2881           InitExpressions.push_back(EndIndex);
2882         }
2883       }
2884       break;
2885     }
2886     }
2887   }
2888
2889   if (Invalid || Init.isInvalid())
2890     return ExprError();
2891
2892   // Clear out the expressions within the designation.
2893   Desig.ClearExprs(*this);
2894
2895   DesignatedInitExpr *DIE
2896     = DesignatedInitExpr::Create(Context,
2897                                  Designators,
2898                                  InitExpressions, Loc, GNUSyntax,
2899                                  Init.getAs<Expr>());
2900
2901   if (!getLangOpts().C99)
2902     Diag(DIE->getLocStart(), diag::ext_designated_init)
2903       << DIE->getSourceRange();
2904
2905   return DIE;
2906 }
2907
2908 //===----------------------------------------------------------------------===//
2909 // Initialization entity
2910 //===----------------------------------------------------------------------===//
2911
2912 InitializedEntity::InitializedEntity(ASTContext &Context, unsigned Index,
2913                                      const InitializedEntity &Parent)
2914   : Parent(&Parent), Index(Index)
2915 {
2916   if (const ArrayType *AT = Context.getAsArrayType(Parent.getType())) {
2917     Kind = EK_ArrayElement;
2918     Type = AT->getElementType();
2919   } else if (const VectorType *VT = Parent.getType()->getAs<VectorType>()) {
2920     Kind = EK_VectorElement;
2921     Type = VT->getElementType();
2922   } else {
2923     const ComplexType *CT = Parent.getType()->getAs<ComplexType>();
2924     assert(CT && "Unexpected type");
2925     Kind = EK_ComplexElement;
2926     Type = CT->getElementType();
2927   }
2928 }
2929
2930 InitializedEntity
2931 InitializedEntity::InitializeBase(ASTContext &Context,
2932                                   const CXXBaseSpecifier *Base,
2933                                   bool IsInheritedVirtualBase,
2934                                   const InitializedEntity *Parent) {
2935   InitializedEntity Result;
2936   Result.Kind = EK_Base;
2937   Result.Parent = Parent;
2938   Result.Base = reinterpret_cast<uintptr_t>(Base);
2939   if (IsInheritedVirtualBase)
2940     Result.Base |= 0x01;
2941
2942   Result.Type = Base->getType();
2943   return Result;
2944 }
2945
2946 DeclarationName InitializedEntity::getName() const {
2947   switch (getKind()) {
2948   case EK_Parameter:
2949   case EK_Parameter_CF_Audited: {
2950     ParmVarDecl *D = reinterpret_cast<ParmVarDecl*>(Parameter & ~0x1);
2951     return (D ? D->getDeclName() : DeclarationName());
2952   }
2953
2954   case EK_Variable:
2955   case EK_Member:
2956   case EK_Binding:
2957     return Variable.VariableOrMember->getDeclName();
2958
2959   case EK_LambdaCapture:
2960     return DeclarationName(Capture.VarID);
2961
2962   case EK_Result:
2963   case EK_Exception:
2964   case EK_New:
2965   case EK_Temporary:
2966   case EK_Base:
2967   case EK_Delegating:
2968   case EK_ArrayElement:
2969   case EK_VectorElement:
2970   case EK_ComplexElement:
2971   case EK_BlockElement:
2972   case EK_LambdaToBlockConversionBlockElement:
2973   case EK_CompoundLiteralInit:
2974   case EK_RelatedResult:
2975     return DeclarationName();
2976   }
2977
2978   llvm_unreachable("Invalid EntityKind!");
2979 }
2980
2981 ValueDecl *InitializedEntity::getDecl() const {
2982   switch (getKind()) {
2983   case EK_Variable:
2984   case EK_Member:
2985   case EK_Binding:
2986     return Variable.VariableOrMember;
2987
2988   case EK_Parameter:
2989   case EK_Parameter_CF_Audited:
2990     return reinterpret_cast<ParmVarDecl*>(Parameter & ~0x1);
2991
2992   case EK_Result:
2993   case EK_Exception:
2994   case EK_New:
2995   case EK_Temporary:
2996   case EK_Base:
2997   case EK_Delegating:
2998   case EK_ArrayElement:
2999   case EK_VectorElement:
3000   case EK_ComplexElement:
3001   case EK_BlockElement:
3002   case EK_LambdaToBlockConversionBlockElement:
3003   case EK_LambdaCapture:
3004   case EK_CompoundLiteralInit:
3005   case EK_RelatedResult:
3006     return nullptr;
3007   }
3008
3009   llvm_unreachable("Invalid EntityKind!");
3010 }
3011
3012 bool InitializedEntity::allowsNRVO() const {
3013   switch (getKind()) {
3014   case EK_Result:
3015   case EK_Exception:
3016     return LocAndNRVO.NRVO;
3017
3018   case EK_Variable:
3019   case EK_Parameter:
3020   case EK_Parameter_CF_Audited:
3021   case EK_Member:
3022   case EK_Binding:
3023   case EK_New:
3024   case EK_Temporary:
3025   case EK_CompoundLiteralInit:
3026   case EK_Base:
3027   case EK_Delegating:
3028   case EK_ArrayElement:
3029   case EK_VectorElement:
3030   case EK_ComplexElement:
3031   case EK_BlockElement:
3032   case EK_LambdaToBlockConversionBlockElement:
3033   case EK_LambdaCapture:
3034   case EK_RelatedResult:
3035     break;
3036   }
3037
3038   return false;
3039 }
3040
3041 unsigned InitializedEntity::dumpImpl(raw_ostream &OS) const {
3042   assert(getParent() != this);
3043   unsigned Depth = getParent() ? getParent()->dumpImpl(OS) : 0;
3044   for (unsigned I = 0; I != Depth; ++I)
3045     OS << "`-";
3046
3047   switch (getKind()) {
3048   case EK_Variable: OS << "Variable"; break;
3049   case EK_Parameter: OS << "Parameter"; break;
3050   case EK_Parameter_CF_Audited: OS << "CF audited function Parameter";
3051     break;
3052   case EK_Result: OS << "Result"; break;
3053   case EK_Exception: OS << "Exception"; break;
3054   case EK_Member: OS << "Member"; break;
3055   case EK_Binding: OS << "Binding"; break;
3056   case EK_New: OS << "New"; break;
3057   case EK_Temporary: OS << "Temporary"; break;
3058   case EK_CompoundLiteralInit: OS << "CompoundLiteral";break;
3059   case EK_RelatedResult: OS << "RelatedResult"; break;
3060   case EK_Base: OS << "Base"; break;
3061   case EK_Delegating: OS << "Delegating"; break;
3062   case EK_ArrayElement: OS << "ArrayElement " << Index; break;
3063   case EK_VectorElement: OS << "VectorElement " << Index; break;
3064   case EK_ComplexElement: OS << "ComplexElement " << Index; break;
3065   case EK_BlockElement: OS << "Block"; break;
3066   case EK_LambdaToBlockConversionBlockElement:
3067     OS << "Block (lambda)";
3068     break;
3069   case EK_LambdaCapture:
3070     OS << "LambdaCapture ";
3071     OS << DeclarationName(Capture.VarID);
3072     break;
3073   }
3074
3075   if (auto *D = getDecl()) {
3076     OS << " ";
3077     D->printQualifiedName(OS);
3078   }
3079
3080   OS << " '" << getType().getAsString() << "'\n";
3081
3082   return Depth + 1;
3083 }
3084
3085 LLVM_DUMP_METHOD void InitializedEntity::dump() const {
3086   dumpImpl(llvm::errs());
3087 }
3088
3089 //===----------------------------------------------------------------------===//
3090 // Initialization sequence
3091 //===----------------------------------------------------------------------===//
3092
3093 void InitializationSequence::Step::Destroy() {
3094   switch (Kind) {
3095   case SK_ResolveAddressOfOverloadedFunction:
3096   case SK_CastDerivedToBaseRValue:
3097   case SK_CastDerivedToBaseXValue:
3098   case SK_CastDerivedToBaseLValue:
3099   case SK_BindReference:
3100   case SK_BindReferenceToTemporary:
3101   case SK_FinalCopy:
3102   case SK_ExtraneousCopyToTemporary:
3103   case SK_UserConversion:
3104   case SK_QualificationConversionRValue:
3105   case SK_QualificationConversionXValue:
3106   case SK_QualificationConversionLValue:
3107   case SK_AtomicConversion:
3108   case SK_LValueToRValue:
3109   case SK_ListInitialization:
3110   case SK_UnwrapInitList:
3111   case SK_RewrapInitList:
3112   case SK_ConstructorInitialization:
3113   case SK_ConstructorInitializationFromList:
3114   case SK_ZeroInitialization:
3115   case SK_CAssignment:
3116   case SK_StringInit:
3117   case SK_ObjCObjectConversion:
3118   case SK_ArrayLoopIndex:
3119   case SK_ArrayLoopInit:
3120   case SK_ArrayInit:
3121   case SK_GNUArrayInit:
3122   case SK_ParenthesizedArrayInit:
3123   case SK_PassByIndirectCopyRestore:
3124   case SK_PassByIndirectRestore:
3125   case SK_ProduceObjCObject:
3126   case SK_StdInitializerList:
3127   case SK_StdInitializerListConstructorCall:
3128   case SK_OCLSamplerInit:
3129   case SK_OCLZeroEvent:
3130   case SK_OCLZeroQueue:
3131     break;
3132
3133   case SK_ConversionSequence:
3134   case SK_ConversionSequenceNoNarrowing:
3135     delete ICS;
3136   }
3137 }
3138
3139 bool InitializationSequence::isDirectReferenceBinding() const {
3140   // There can be some lvalue adjustments after the SK_BindReference step.
3141   for (auto I = Steps.rbegin(); I != Steps.rend(); ++I) {
3142     if (I->Kind == SK_BindReference)
3143       return true;
3144     if (I->Kind == SK_BindReferenceToTemporary)
3145       return false;
3146   }
3147   return false;
3148 }
3149
3150 bool InitializationSequence::isAmbiguous() const {
3151   if (!Failed())
3152     return false;
3153
3154   switch (getFailureKind()) {
3155   case FK_TooManyInitsForReference:
3156   case FK_ParenthesizedListInitForReference:
3157   case FK_ArrayNeedsInitList:
3158   case FK_ArrayNeedsInitListOrStringLiteral:
3159   case FK_ArrayNeedsInitListOrWideStringLiteral:
3160   case FK_NarrowStringIntoWideCharArray:
3161   case FK_WideStringIntoCharArray:
3162   case FK_IncompatWideStringIntoWideChar:
3163   case FK_AddressOfOverloadFailed: // FIXME: Could do better
3164   case FK_NonConstLValueReferenceBindingToTemporary:
3165   case FK_NonConstLValueReferenceBindingToBitfield:
3166   case FK_NonConstLValueReferenceBindingToVectorElement:
3167   case FK_NonConstLValueReferenceBindingToUnrelated:
3168   case FK_RValueReferenceBindingToLValue:
3169   case FK_ReferenceInitDropsQualifiers:
3170   case FK_ReferenceInitFailed:
3171   case FK_ConversionFailed:
3172   case FK_ConversionFromPropertyFailed:
3173   case FK_TooManyInitsForScalar:
3174   case FK_ParenthesizedListInitForScalar:
3175   case FK_ReferenceBindingToInitList:
3176   case FK_InitListBadDestinationType:
3177   case FK_DefaultInitOfConst:
3178   case FK_Incomplete:
3179   case FK_ArrayTypeMismatch:
3180   case FK_NonConstantArrayInit:
3181   case FK_ListInitializationFailed:
3182   case FK_VariableLengthArrayHasInitializer:
3183   case FK_PlaceholderType:
3184   case FK_ExplicitConstructor:
3185   case FK_AddressOfUnaddressableFunction:
3186     return false;
3187
3188   case FK_ReferenceInitOverloadFailed:
3189   case FK_UserConversionOverloadFailed:
3190   case FK_ConstructorOverloadFailed:
3191   case FK_ListConstructorOverloadFailed:
3192     return FailedOverloadResult == OR_Ambiguous;
3193   }
3194
3195   llvm_unreachable("Invalid EntityKind!");
3196 }
3197
3198 bool InitializationSequence::isConstructorInitialization() const {
3199   return !Steps.empty() && Steps.back().Kind == SK_ConstructorInitialization;
3200 }
3201
3202 void
3203 InitializationSequence
3204 ::AddAddressOverloadResolutionStep(FunctionDecl *Function,
3205                                    DeclAccessPair Found,
3206                                    bool HadMultipleCandidates) {
3207   Step S;
3208   S.Kind = SK_ResolveAddressOfOverloadedFunction;
3209   S.Type = Function->getType();
3210   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3211   S.Function.Function = Function;
3212   S.Function.FoundDecl = Found;
3213   Steps.push_back(S);
3214 }
3215
3216 void InitializationSequence::AddDerivedToBaseCastStep(QualType BaseType,
3217                                                       ExprValueKind VK) {
3218   Step S;
3219   switch (VK) {
3220   case VK_RValue: S.Kind = SK_CastDerivedToBaseRValue; break;
3221   case VK_XValue: S.Kind = SK_CastDerivedToBaseXValue; break;
3222   case VK_LValue: S.Kind = SK_CastDerivedToBaseLValue; break;
3223   }
3224   S.Type = BaseType;
3225   Steps.push_back(S);
3226 }
3227
3228 void InitializationSequence::AddReferenceBindingStep(QualType T,
3229                                                      bool BindingTemporary) {
3230   Step S;
3231   S.Kind = BindingTemporary? SK_BindReferenceToTemporary : SK_BindReference;
3232   S.Type = T;
3233   Steps.push_back(S);
3234 }
3235
3236 void InitializationSequence::AddFinalCopy(QualType T) {
3237   Step S;
3238   S.Kind = SK_FinalCopy;
3239   S.Type = T;
3240   Steps.push_back(S);
3241 }
3242
3243 void InitializationSequence::AddExtraneousCopyToTemporary(QualType T) {
3244   Step S;
3245   S.Kind = SK_ExtraneousCopyToTemporary;
3246   S.Type = T;
3247   Steps.push_back(S);
3248 }
3249
3250 void
3251 InitializationSequence::AddUserConversionStep(FunctionDecl *Function,
3252                                               DeclAccessPair FoundDecl,
3253                                               QualType T,
3254                                               bool HadMultipleCandidates) {
3255   Step S;
3256   S.Kind = SK_UserConversion;
3257   S.Type = T;
3258   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3259   S.Function.Function = Function;
3260   S.Function.FoundDecl = FoundDecl;
3261   Steps.push_back(S);
3262 }
3263
3264 void InitializationSequence::AddQualificationConversionStep(QualType Ty,
3265                                                             ExprValueKind VK) {
3266   Step S;
3267   S.Kind = SK_QualificationConversionRValue; // work around a gcc warning
3268   switch (VK) {
3269   case VK_RValue:
3270     S.Kind = SK_QualificationConversionRValue;
3271     break;
3272   case VK_XValue:
3273     S.Kind = SK_QualificationConversionXValue;
3274     break;
3275   case VK_LValue:
3276     S.Kind = SK_QualificationConversionLValue;
3277     break;
3278   }
3279   S.Type = Ty;
3280   Steps.push_back(S);
3281 }
3282
3283 void InitializationSequence::AddAtomicConversionStep(QualType Ty) {
3284   Step S;
3285   S.Kind = SK_AtomicConversion;
3286   S.Type = Ty;
3287   Steps.push_back(S);
3288 }
3289
3290 void InitializationSequence::AddLValueToRValueStep(QualType Ty) {
3291   assert(!Ty.hasQualifiers() && "rvalues may not have qualifiers");
3292
3293   Step S;
3294   S.Kind = SK_LValueToRValue;
3295   S.Type = Ty;
3296   Steps.push_back(S);
3297 }
3298
3299 void InitializationSequence::AddConversionSequenceStep(
3300     const ImplicitConversionSequence &ICS, QualType T,
3301     bool TopLevelOfInitList) {
3302   Step S;
3303   S.Kind = TopLevelOfInitList ? SK_ConversionSequenceNoNarrowing
3304                               : SK_ConversionSequence;
3305   S.Type = T;
3306   S.ICS = new ImplicitConversionSequence(ICS);
3307   Steps.push_back(S);
3308 }
3309
3310 void InitializationSequence::AddListInitializationStep(QualType T) {
3311   Step S;
3312   S.Kind = SK_ListInitialization;
3313   S.Type = T;
3314   Steps.push_back(S);
3315 }
3316
3317 void InitializationSequence::AddConstructorInitializationStep(
3318     DeclAccessPair FoundDecl, CXXConstructorDecl *Constructor, QualType T,
3319     bool HadMultipleCandidates, bool FromInitList, bool AsInitList) {
3320   Step S;
3321   S.Kind = FromInitList ? AsInitList ? SK_StdInitializerListConstructorCall
3322                                      : SK_ConstructorInitializationFromList
3323                         : SK_ConstructorInitialization;
3324   S.Type = T;
3325   S.Function.HadMultipleCandidates = HadMultipleCandidates;
3326   S.Function.Function = Constructor;
3327   S.Function.FoundDecl = FoundDecl;
3328   Steps.push_back(S);
3329 }
3330
3331 void InitializationSequence::AddZeroInitializationStep(QualType T) {
3332   Step S;
3333   S.Kind = SK_ZeroInitialization;
3334   S.Type = T;
3335   Steps.push_back(S);
3336 }
3337
3338 void InitializationSequence::AddCAssignmentStep(QualType T) {
3339   Step S;
3340   S.Kind = SK_CAssignment;
3341   S.Type = T;
3342   Steps.push_back(S);
3343 }
3344
3345 void InitializationSequence::AddStringInitStep(QualType T) {
3346   Step S;
3347   S.Kind = SK_StringInit;
3348   S.Type = T;
3349   Steps.push_back(S);
3350 }
3351
3352 void InitializationSequence::AddObjCObjectConversionStep(QualType T) {
3353   Step S;
3354   S.Kind = SK_ObjCObjectConversion;
3355   S.Type = T;
3356   Steps.push_back(S);
3357 }
3358
3359 void InitializationSequence::AddArrayInitStep(QualType T, bool IsGNUExtension) {
3360   Step S;
3361   S.Kind = IsGNUExtension ? SK_GNUArrayInit : SK_ArrayInit;
3362   S.Type = T;
3363   Steps.push_back(S);
3364 }
3365
3366 void InitializationSequence::AddArrayInitLoopStep(QualType T, QualType EltT) {
3367   Step S;
3368   S.Kind = SK_ArrayLoopIndex;
3369   S.Type = EltT;
3370   Steps.insert(Steps.begin(), S);
3371
3372   S.Kind = SK_ArrayLoopInit;
3373   S.Type = T;
3374   Steps.push_back(S);
3375 }
3376
3377 void InitializationSequence::AddParenthesizedArrayInitStep(QualType T) {
3378   Step S;
3379   S.Kind = SK_ParenthesizedArrayInit;
3380   S.Type = T;
3381   Steps.push_back(S);
3382 }
3383
3384 void InitializationSequence::AddPassByIndirectCopyRestoreStep(QualType type,
3385                                                               bool shouldCopy) {
3386   Step s;
3387   s.Kind = (shouldCopy ? SK_PassByIndirectCopyRestore
3388                        : SK_PassByIndirectRestore);
3389   s.Type = type;
3390   Steps.push_back(s);
3391 }
3392
3393 void InitializationSequence::AddProduceObjCObjectStep(QualType T) {
3394   Step S;
3395   S.Kind = SK_ProduceObjCObject;
3396   S.Type = T;
3397   Steps.push_back(S);
3398 }
3399
3400 void InitializationSequence::AddStdInitializerListConstructionStep(QualType T) {
3401   Step S;
3402   S.Kind = SK_StdInitializerList;
3403   S.Type = T;
3404   Steps.push_back(S);
3405 }
3406
3407 void InitializationSequence::AddOCLSamplerInitStep(QualType T) {
3408   Step S;
3409   S.Kind = SK_OCLSamplerInit;
3410   S.Type = T;
3411   Steps.push_back(S);
3412 }
3413
3414 void InitializationSequence::AddOCLZeroEventStep(QualType T) {
3415   Step S;
3416   S.Kind = SK_OCLZeroEvent;
3417   S.Type = T;
3418   Steps.push_back(S);
3419 }
3420
3421 void InitializationSequence::AddOCLZeroQueueStep(QualType T) {
3422   Step S;
3423   S.Kind = SK_OCLZeroQueue;
3424   S.Type = T;
3425   Steps.push_back(S);
3426 }
3427
3428 void InitializationSequence::RewrapReferenceInitList(QualType T,
3429                                                      InitListExpr *Syntactic) {
3430   assert(Syntactic->getNumInits() == 1 &&
3431          "Can only rewrap trivial init lists.");
3432   Step S;
3433   S.Kind = SK_UnwrapInitList;
3434   S.Type = Syntactic->getInit(0)->getType();
3435   Steps.insert(Steps.begin(), S);
3436
3437   S.Kind = SK_RewrapInitList;
3438   S.Type = T;
3439   S.WrappingSyntacticList = Syntactic;
3440   Steps.push_back(S);
3441 }
3442
3443 void InitializationSequence::SetOverloadFailure(FailureKind Failure,
3444                                                 OverloadingResult Result) {
3445   setSequenceKind(FailedSequence);
3446   this->Failure = Failure;
3447   this->FailedOverloadResult = Result;
3448 }
3449
3450 //===----------------------------------------------------------------------===//
3451 // Attempt initialization
3452 //===----------------------------------------------------------------------===//
3453
3454 /// Tries to add a zero initializer. Returns true if that worked.
3455 static bool
3456 maybeRecoverWithZeroInitialization(Sema &S, InitializationSequence &Sequence,
3457                                    const InitializedEntity &Entity) {
3458   if (Entity.getKind() != InitializedEntity::EK_Variable)
3459     return false;
3460
3461   VarDecl *VD = cast<VarDecl>(Entity.getDecl());
3462   if (VD->getInit() || VD->getLocEnd().isMacroID())
3463     return false;
3464
3465   QualType VariableTy = VD->getType().getCanonicalType();
3466   SourceLocation Loc = S.getLocForEndOfToken(VD->getLocEnd());
3467   std::string Init = S.getFixItZeroInitializerForType(VariableTy, Loc);
3468   if (!Init.empty()) {
3469     Sequence.AddZeroInitializationStep(Entity.getType());
3470     Sequence.SetZeroInitializationFixit(Init, Loc);
3471     return true;
3472   }
3473   return false;
3474 }
3475
3476 static void MaybeProduceObjCObject(Sema &S,
3477                                    InitializationSequence &Sequence,
3478                                    const InitializedEntity &Entity) {
3479   if (!S.getLangOpts().ObjCAutoRefCount) return;
3480
3481   /// When initializing a parameter, produce the value if it's marked
3482   /// __attribute__((ns_consumed)).
3483   if (Entity.isParameterKind()) {
3484     if (!Entity.isParameterConsumed())
3485       return;
3486
3487     assert(Entity.getType()->isObjCRetainableType() &&
3488            "consuming an object of unretainable type?");
3489     Sequence.AddProduceObjCObjectStep(Entity.getType());
3490
3491   /// When initializing a return value, if the return type is a
3492   /// retainable type, then returns need to immediately retain the
3493   /// object.  If an autorelease is required, it will be done at the
3494   /// last instant.
3495   } else if (Entity.getKind() == InitializedEntity::EK_Result) {
3496     if (!Entity.getType()->isObjCRetainableType())
3497       return;
3498
3499     Sequence.AddProduceObjCObjectStep(Entity.getType());
3500   }
3501 }
3502
3503 static void TryListInitialization(Sema &S,
3504                                   const InitializedEntity &Entity,
3505                                   const InitializationKind &Kind,
3506                                   InitListExpr *InitList,
3507                                   InitializationSequence &Sequence,
3508                                   bool TreatUnavailableAsInvalid);
3509
3510 /// \brief When initializing from init list via constructor, handle
3511 /// initialization of an object of type std::initializer_list<T>.
3512 ///
3513 /// \return true if we have handled initialization of an object of type
3514 /// std::initializer_list<T>, false otherwise.
3515 static bool TryInitializerListConstruction(Sema &S,
3516                                            InitListExpr *List,
3517                                            QualType DestType,
3518                                            InitializationSequence &Sequence,
3519                                            bool TreatUnavailableAsInvalid) {
3520   QualType E;
3521   if (!S.isStdInitializerList(DestType, &E))
3522     return false;
3523
3524   if (!S.isCompleteType(List->getExprLoc(), E)) {
3525     Sequence.setIncompleteTypeFailure(E);
3526     return true;
3527   }
3528
3529   // Try initializing a temporary array from the init list.
3530   QualType ArrayType = S.Context.getConstantArrayType(
3531       E.withConst(), llvm::APInt(S.Context.getTypeSize(S.Context.getSizeType()),
3532                                  List->getNumInits()),
3533       clang::ArrayType::Normal, 0);
3534   InitializedEntity HiddenArray =
3535       InitializedEntity::InitializeTemporary(ArrayType);
3536   InitializationKind Kind =
3537       InitializationKind::CreateDirectList(List->getExprLoc());
3538   TryListInitialization(S, HiddenArray, Kind, List, Sequence,
3539                         TreatUnavailableAsInvalid);
3540   if (Sequence)
3541     Sequence.AddStdInitializerListConstructionStep(DestType);
3542   return true;
3543 }
3544
3545 /// Determine if the constructor has the signature of a copy or move
3546 /// constructor for the type T of the class in which it was found. That is,
3547 /// determine if its first parameter is of type T or reference to (possibly
3548 /// cv-qualified) T.
3549 static bool hasCopyOrMoveCtorParam(ASTContext &Ctx,
3550                                    const ConstructorInfo &Info) {
3551   if (Info.Constructor->getNumParams() == 0)
3552     return false;
3553
3554   QualType ParmT =
3555       Info.Constructor->getParamDecl(0)->getType().getNonReferenceType();
3556   QualType ClassT =
3557       Ctx.getRecordType(cast<CXXRecordDecl>(Info.FoundDecl->getDeclContext()));
3558
3559   return Ctx.hasSameUnqualifiedType(ParmT, ClassT);
3560 }
3561
3562 static OverloadingResult
3563 ResolveConstructorOverload(Sema &S, SourceLocation DeclLoc,
3564                            MultiExprArg Args,
3565                            OverloadCandidateSet &CandidateSet,
3566                            QualType DestType,
3567                            DeclContext::lookup_result Ctors,
3568                            OverloadCandidateSet::iterator &Best,
3569                            bool CopyInitializing, bool AllowExplicit,
3570                            bool OnlyListConstructors, bool IsListInit,
3571                            bool SecondStepOfCopyInit = false) {
3572   CandidateSet.clear(OverloadCandidateSet::CSK_InitByConstructor);
3573
3574   for (NamedDecl *D : Ctors) {
3575     auto Info = getConstructorInfo(D);
3576     if (!Info.Constructor || Info.Constructor->isInvalidDecl())
3577       continue;
3578
3579     if (!AllowExplicit && Info.Constructor->isExplicit())
3580       continue;
3581
3582     if (OnlyListConstructors && !S.isInitListConstructor(Info.Constructor))
3583       continue;
3584
3585     // C++11 [over.best.ics]p4:
3586     //   ... and the constructor or user-defined conversion function is a
3587     //   candidate by
3588     //   - 13.3.1.3, when the argument is the temporary in the second step
3589     //     of a class copy-initialization, or
3590     //   - 13.3.1.4, 13.3.1.5, or 13.3.1.6 (in all cases), [not handled here]
3591     //   - the second phase of 13.3.1.7 when the initializer list has exactly
3592     //     one element that is itself an initializer list, and the target is
3593     //     the first parameter of a constructor of class X, and the conversion
3594     //     is to X or reference to (possibly cv-qualified X),
3595     //   user-defined conversion sequences are not considered.
3596     bool SuppressUserConversions =
3597         SecondStepOfCopyInit ||
3598         (IsListInit && Args.size() == 1 && isa<InitListExpr>(Args[0]) &&
3599          hasCopyOrMoveCtorParam(S.Context, Info));
3600
3601     if (Info.ConstructorTmpl)
3602       S.AddTemplateOverloadCandidate(Info.ConstructorTmpl, Info.FoundDecl,
3603                                      /*ExplicitArgs*/ nullptr, Args,
3604                                      CandidateSet, SuppressUserConversions);
3605     else {
3606       // C++ [over.match.copy]p1:
3607       //   - When initializing a temporary to be bound to the first parameter
3608       //     of a constructor [for type T] that takes a reference to possibly
3609       //     cv-qualified T as its first argument, called with a single
3610       //     argument in the context of direct-initialization, explicit
3611       //     conversion functions are also considered.
3612       // FIXME: What if a constructor template instantiates to such a signature?
3613       bool AllowExplicitConv = AllowExplicit && !CopyInitializing &&
3614                                Args.size() == 1 &&
3615                                hasCopyOrMoveCtorParam(S.Context, Info);
3616       S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl, Args,
3617                              CandidateSet, SuppressUserConversions,
3618                              /*PartialOverloading=*/false,
3619                              /*AllowExplicit=*/AllowExplicitConv);
3620     }
3621   }
3622
3623   // FIXME: Work around a bug in C++17 guaranteed copy elision.
3624   //
3625   // When initializing an object of class type T by constructor
3626   // ([over.match.ctor]) or by list-initialization ([over.match.list])
3627   // from a single expression of class type U, conversion functions of
3628   // U that convert to the non-reference type cv T are candidates.
3629   // Explicit conversion functions are only candidates during
3630   // direct-initialization.
3631   //
3632   // Note: SecondStepOfCopyInit is only ever true in this case when
3633   // evaluating whether to produce a C++98 compatibility warning.
3634   if (S.getLangOpts().CPlusPlus17 && Args.size() == 1 &&
3635       !SecondStepOfCopyInit) {
3636     Expr *Initializer = Args[0];
3637     auto *SourceRD = Initializer->getType()->getAsCXXRecordDecl();
3638     if (SourceRD && S.isCompleteType(DeclLoc, Initializer->getType())) {
3639       const auto &Conversions = SourceRD->getVisibleConversionFunctions();
3640       for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
3641         NamedDecl *D = *I;
3642         CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
3643         D = D->getUnderlyingDecl();
3644
3645         FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
3646         CXXConversionDecl *Conv;
3647         if (ConvTemplate)
3648           Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
3649         else
3650           Conv = cast<CXXConversionDecl>(D);
3651
3652         if ((AllowExplicit && !CopyInitializing) || !Conv->isExplicit()) {
3653           if (ConvTemplate)
3654             S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(),
3655                                              ActingDC, Initializer, DestType,
3656                                              CandidateSet, AllowExplicit,
3657                                              /*AllowResultConversion*/false);
3658           else
3659             S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Initializer,
3660                                      DestType, CandidateSet, AllowExplicit,
3661                                      /*AllowResultConversion*/false);
3662         }
3663       }
3664     }
3665   }
3666
3667   // Perform overload resolution and return the result.
3668   return CandidateSet.BestViableFunction(S, DeclLoc, Best);
3669 }
3670
3671 /// \brief Attempt initialization by constructor (C++ [dcl.init]), which
3672 /// enumerates the constructors of the initialized entity and performs overload
3673 /// resolution to select the best.
3674 /// \param DestType       The destination class type.
3675 /// \param DestArrayType  The destination type, which is either DestType or
3676 ///                       a (possibly multidimensional) array of DestType.
3677 /// \param IsListInit     Is this list-initialization?
3678 /// \param IsInitListCopy Is this non-list-initialization resulting from a
3679 ///                       list-initialization from {x} where x is the same
3680 ///                       type as the entity?
3681 static void TryConstructorInitialization(Sema &S,
3682                                          const InitializedEntity &Entity,
3683                                          const InitializationKind &Kind,
3684                                          MultiExprArg Args, QualType DestType,
3685                                          QualType DestArrayType,
3686                                          InitializationSequence &Sequence,
3687                                          bool IsListInit = false,
3688                                          bool IsInitListCopy = false) {
3689   assert(((!IsListInit && !IsInitListCopy) ||
3690           (Args.size() == 1 && isa<InitListExpr>(Args[0]))) &&
3691          "IsListInit/IsInitListCopy must come with a single initializer list "
3692          "argument.");
3693   InitListExpr *ILE =
3694       (IsListInit || IsInitListCopy) ? cast<InitListExpr>(Args[0]) : nullptr;
3695   MultiExprArg UnwrappedArgs =
3696       ILE ? MultiExprArg(ILE->getInits(), ILE->getNumInits()) : Args;
3697
3698   // The type we're constructing needs to be complete.
3699   if (!S.isCompleteType(Kind.getLocation(), DestType)) {
3700     Sequence.setIncompleteTypeFailure(DestType);
3701     return;
3702   }
3703
3704   // C++17 [dcl.init]p17:
3705   //     - If the initializer expression is a prvalue and the cv-unqualified
3706   //       version of the source type is the same class as the class of the
3707   //       destination, the initializer expression is used to initialize the
3708   //       destination object.
3709   // Per DR (no number yet), this does not apply when initializing a base
3710   // class or delegating to another constructor from a mem-initializer.
3711   // ObjC++: Lambda captured by the block in the lambda to block conversion
3712   // should avoid copy elision.
3713   if (S.getLangOpts().CPlusPlus17 &&
3714       Entity.getKind() != InitializedEntity::EK_Base &&
3715       Entity.getKind() != InitializedEntity::EK_Delegating &&
3716       Entity.getKind() !=
3717           InitializedEntity::EK_LambdaToBlockConversionBlockElement &&
3718       UnwrappedArgs.size() == 1 && UnwrappedArgs[0]->isRValue() &&
3719       S.Context.hasSameUnqualifiedType(UnwrappedArgs[0]->getType(), DestType)) {
3720     // Convert qualifications if necessary.
3721     Sequence.AddQualificationConversionStep(DestType, VK_RValue);
3722     if (ILE)
3723       Sequence.RewrapReferenceInitList(DestType, ILE);
3724     return;
3725   }
3726
3727   const RecordType *DestRecordType = DestType->getAs<RecordType>();
3728   assert(DestRecordType && "Constructor initialization requires record type");
3729   CXXRecordDecl *DestRecordDecl
3730     = cast<CXXRecordDecl>(DestRecordType->getDecl());
3731
3732   // Build the candidate set directly in the initialization sequence
3733   // structure, so that it will persist if we fail.
3734   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
3735
3736   // Determine whether we are allowed to call explicit constructors or
3737   // explicit conversion operators.
3738   bool AllowExplicit = Kind.AllowExplicit() || IsListInit;
3739   bool CopyInitialization = Kind.getKind() == InitializationKind::IK_Copy;
3740
3741   //   - Otherwise, if T is a class type, constructors are considered. The
3742   //     applicable constructors are enumerated, and the best one is chosen
3743   //     through overload resolution.
3744   DeclContext::lookup_result Ctors = S.LookupConstructors(DestRecordDecl);
3745
3746   OverloadingResult Result = OR_No_Viable_Function;
3747   OverloadCandidateSet::iterator Best;
3748   bool AsInitializerList = false;
3749
3750   // C++11 [over.match.list]p1, per DR1467:
3751   //   When objects of non-aggregate type T are list-initialized, such that
3752   //   8.5.4 [dcl.init.list] specifies that overload resolution is performed
3753   //   according to the rules in this section, overload resolution selects
3754   //   the constructor in two phases:
3755   //
3756   //   - Initially, the candidate functions are the initializer-list
3757   //     constructors of the class T and the argument list consists of the
3758   //     initializer list as a single argument.
3759   if (IsListInit) {
3760     AsInitializerList = true;
3761
3762     // If the initializer list has no elements and T has a default constructor,
3763     // the first phase is omitted.
3764     if (!(UnwrappedArgs.empty() && DestRecordDecl->hasDefaultConstructor()))
3765       Result = ResolveConstructorOverload(S, Kind.getLocation(), Args,
3766                                           CandidateSet, DestType, Ctors, Best,
3767                                           CopyInitialization, AllowExplicit,
3768                                           /*OnlyListConstructor=*/true,
3769                                           IsListInit);
3770   }
3771
3772   // C++11 [over.match.list]p1:
3773   //   - If no viable initializer-list constructor is found, overload resolution
3774   //     is performed again, where the candidate functions are all the
3775   //     constructors of the class T and the argument list consists of the
3776   //     elements of the initializer list.
3777   if (Result == OR_No_Viable_Function) {
3778     AsInitializerList = false;
3779     Result = ResolveConstructorOverload(S, Kind.getLocation(), UnwrappedArgs,
3780                                         CandidateSet, DestType, Ctors, Best,
3781                                         CopyInitialization, AllowExplicit,
3782                                         /*OnlyListConstructors=*/false,
3783                                         IsListInit);
3784   }
3785   if (Result) {
3786     Sequence.SetOverloadFailure(IsListInit ?
3787                       InitializationSequence::FK_ListConstructorOverloadFailed :
3788                       InitializationSequence::FK_ConstructorOverloadFailed,
3789                                 Result);
3790     return;
3791   }
3792
3793   bool HadMultipleCandidates = (CandidateSet.size() > 1);
3794
3795   // In C++17, ResolveConstructorOverload can select a conversion function
3796   // instead of a constructor.
3797   if (auto *CD = dyn_cast<CXXConversionDecl>(Best->Function)) {
3798     // Add the user-defined conversion step that calls the conversion function.
3799     QualType ConvType = CD->getConversionType();
3800     assert(S.Context.hasSameUnqualifiedType(ConvType, DestType) &&
3801            "should not have selected this conversion function");
3802     Sequence.AddUserConversionStep(CD, Best->FoundDecl, ConvType,
3803                                    HadMultipleCandidates);
3804     if (!S.Context.hasSameType(ConvType, DestType))
3805       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
3806     if (IsListInit)
3807       Sequence.RewrapReferenceInitList(Entity.getType(), ILE);
3808     return;
3809   }
3810
3811   // C++11 [dcl.init]p6:
3812   //   If a program calls for the default initialization of an object
3813   //   of a const-qualified type T, T shall be a class type with a
3814   //   user-provided default constructor.
3815   // C++ core issue 253 proposal:
3816   //   If the implicit default constructor initializes all subobjects, no
3817   //   initializer should be required.
3818   // The 253 proposal is for example needed to process libstdc++ headers in 5.x.
3819   CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
3820   if (Kind.getKind() == InitializationKind::IK_Default &&
3821       Entity.getType().isConstQualified()) {
3822     if (!CtorDecl->getParent()->allowConstDefaultInit()) {
3823       if (!maybeRecoverWithZeroInitialization(S, Sequence, Entity))
3824         Sequence.SetFailed(InitializationSequence::FK_DefaultInitOfConst);
3825       return;
3826     }
3827   }
3828
3829   // C++11 [over.match.list]p1:
3830   //   In copy-list-initialization, if an explicit constructor is chosen, the
3831   //   initializer is ill-formed.
3832   if (IsListInit && !Kind.AllowExplicit() && CtorDecl->isExplicit()) {
3833     Sequence.SetFailed(InitializationSequence::FK_ExplicitConstructor);
3834     return;
3835   }
3836
3837   // Add the constructor initialization step. Any cv-qualification conversion is
3838   // subsumed by the initialization.
3839   Sequence.AddConstructorInitializationStep(
3840       Best->FoundDecl, CtorDecl, DestArrayType, HadMultipleCandidates,
3841       IsListInit | IsInitListCopy, AsInitializerList);
3842 }
3843
3844 static bool
3845 ResolveOverloadedFunctionForReferenceBinding(Sema &S,
3846                                              Expr *Initializer,
3847                                              QualType &SourceType,
3848                                              QualType &UnqualifiedSourceType,
3849                                              QualType UnqualifiedTargetType,
3850                                              InitializationSequence &Sequence) {
3851   if (S.Context.getCanonicalType(UnqualifiedSourceType) ==
3852         S.Context.OverloadTy) {
3853     DeclAccessPair Found;
3854     bool HadMultipleCandidates = false;
3855     if (FunctionDecl *Fn
3856         = S.ResolveAddressOfOverloadedFunction(Initializer,
3857                                                UnqualifiedTargetType,
3858                                                false, Found,
3859                                                &HadMultipleCandidates)) {
3860       Sequence.AddAddressOverloadResolutionStep(Fn, Found,
3861                                                 HadMultipleCandidates);
3862       SourceType = Fn->getType();
3863       UnqualifiedSourceType = SourceType.getUnqualifiedType();
3864     } else if (!UnqualifiedTargetType->isRecordType()) {
3865       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
3866       return true;
3867     }
3868   }
3869   return false;
3870 }
3871
3872 static void TryReferenceInitializationCore(Sema &S,
3873                                            const InitializedEntity &Entity,
3874                                            const InitializationKind &Kind,
3875                                            Expr *Initializer,
3876                                            QualType cv1T1, QualType T1,
3877                                            Qualifiers T1Quals,
3878                                            QualType cv2T2, QualType T2,
3879                                            Qualifiers T2Quals,
3880                                            InitializationSequence &Sequence);
3881
3882 static void TryValueInitialization(Sema &S,
3883                                    const InitializedEntity &Entity,
3884                                    const InitializationKind &Kind,
3885                                    InitializationSequence &Sequence,
3886                                    InitListExpr *InitList = nullptr);
3887
3888 /// \brief Attempt list initialization of a reference.
3889 static void TryReferenceListInitialization(Sema &S,
3890                                            const InitializedEntity &Entity,
3891                                            const InitializationKind &Kind,
3892                                            InitListExpr *InitList,
3893                                            InitializationSequence &Sequence,
3894                                            bool TreatUnavailableAsInvalid) {
3895   // First, catch C++03 where this isn't possible.
3896   if (!S.getLangOpts().CPlusPlus11) {
3897     Sequence.SetFailed(InitializationSequence::FK_ReferenceBindingToInitList);
3898     return;
3899   }
3900   // Can't reference initialize a compound literal.
3901   if (Entity.getKind() == InitializedEntity::EK_CompoundLiteralInit) {
3902     Sequence.SetFailed(InitializationSequence::FK_ReferenceBindingToInitList);
3903     return;
3904   }
3905
3906   QualType DestType = Entity.getType();
3907   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
3908   Qualifiers T1Quals;
3909   QualType T1 = S.Context.getUnqualifiedArrayType(cv1T1, T1Quals);
3910
3911   // Reference initialization via an initializer list works thus:
3912   // If the initializer list consists of a single element that is
3913   // reference-related to the referenced type, bind directly to that element
3914   // (possibly creating temporaries).
3915   // Otherwise, initialize a temporary with the initializer list and
3916   // bind to that.
3917   if (InitList->getNumInits() == 1) {
3918     Expr *Initializer = InitList->getInit(0);
3919     QualType cv2T2 = Initializer->getType();
3920     Qualifiers T2Quals;
3921     QualType T2 = S.Context.getUnqualifiedArrayType(cv2T2, T2Quals);
3922
3923     // If this fails, creating a temporary wouldn't work either.
3924     if (ResolveOverloadedFunctionForReferenceBinding(S, Initializer, cv2T2, T2,
3925                                                      T1, Sequence))
3926       return;
3927
3928     SourceLocation DeclLoc = Initializer->getLocStart();
3929     bool dummy1, dummy2, dummy3;
3930     Sema::ReferenceCompareResult RefRelationship
3931       = S.CompareReferenceRelationship(DeclLoc, cv1T1, cv2T2, dummy1,
3932                                        dummy2, dummy3);
3933     if (RefRelationship >= Sema::Ref_Related) {
3934       // Try to bind the reference here.
3935       TryReferenceInitializationCore(S, Entity, Kind, Initializer, cv1T1, T1,
3936                                      T1Quals, cv2T2, T2, T2Quals, Sequence);
3937       if (Sequence)
3938         Sequence.RewrapReferenceInitList(cv1T1, InitList);
3939       return;
3940     }
3941
3942     // Update the initializer if we've resolved an overloaded function.
3943     if (Sequence.step_begin() != Sequence.step_end())
3944       Sequence.RewrapReferenceInitList(cv1T1, InitList);
3945   }
3946
3947   // Not reference-related. Create a temporary and bind to that.
3948   InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(cv1T1);
3949
3950   TryListInitialization(S, TempEntity, Kind, InitList, Sequence,
3951                         TreatUnavailableAsInvalid);
3952   if (Sequence) {
3953     if (DestType->isRValueReferenceType() ||
3954         (T1Quals.hasConst() && !T1Quals.hasVolatile()))
3955       Sequence.AddReferenceBindingStep(cv1T1, /*bindingTemporary=*/true);
3956     else
3957       Sequence.SetFailed(
3958           InitializationSequence::FK_NonConstLValueReferenceBindingToTemporary);
3959   }
3960 }
3961
3962 /// \brief Attempt list initialization (C++0x [dcl.init.list])
3963 static void TryListInitialization(Sema &S,
3964                                   const InitializedEntity &Entity,
3965                                   const InitializationKind &Kind,
3966                                   InitListExpr *InitList,
3967                                   InitializationSequence &Sequence,
3968                                   bool TreatUnavailableAsInvalid) {
3969   QualType DestType = Entity.getType();
3970
3971   // C++ doesn't allow scalar initialization with more than one argument.
3972   // But C99 complex numbers are scalars and it makes sense there.
3973   if (S.getLangOpts().CPlusPlus && DestType->isScalarType() &&
3974       !DestType->isAnyComplexType() && InitList->getNumInits() > 1) {
3975     Sequence.SetFailed(InitializationSequence::FK_TooManyInitsForScalar);
3976     return;
3977   }
3978   if (DestType->isReferenceType()) {
3979     TryReferenceListInitialization(S, Entity, Kind, InitList, Sequence,
3980                                    TreatUnavailableAsInvalid);
3981     return;
3982   }
3983
3984   if (DestType->isRecordType() &&
3985       !S.isCompleteType(InitList->getLocStart(), DestType)) {
3986     Sequence.setIncompleteTypeFailure(DestType);
3987     return;
3988   }
3989
3990   // C++11 [dcl.init.list]p3, per DR1467:
3991   // - If T is a class type and the initializer list has a single element of
3992   //   type cv U, where U is T or a class derived from T, the object is
3993   //   initialized from that element (by copy-initialization for
3994   //   copy-list-initialization, or by direct-initialization for
3995   //   direct-list-initialization).
3996   // - Otherwise, if T is a character array and the initializer list has a
3997   //   single element that is an appropriately-typed string literal
3998   //   (8.5.2 [dcl.init.string]), initialization is performed as described
3999   //   in that section.
4000   // - Otherwise, if T is an aggregate, [...] (continue below).
4001   if (S.getLangOpts().CPlusPlus11 && InitList->getNumInits() == 1) {
4002     if (DestType->isRecordType()) {
4003       QualType InitType = InitList->getInit(0)->getType();
4004       if (S.Context.hasSameUnqualifiedType(InitType, DestType) ||
4005           S.IsDerivedFrom(InitList->getLocStart(), InitType, DestType)) {
4006         Expr *InitListAsExpr = InitList;
4007         TryConstructorInitialization(S, Entity, Kind, InitListAsExpr, DestType,
4008                                      DestType, Sequence,
4009                                      /*InitListSyntax*/false,
4010                                      /*IsInitListCopy*/true);
4011         return;
4012       }
4013     }
4014     if (const ArrayType *DestAT = S.Context.getAsArrayType(DestType)) {
4015       Expr *SubInit[1] = {InitList->getInit(0)};
4016       if (!isa<VariableArrayType>(DestAT) &&
4017           IsStringInit(SubInit[0], DestAT, S.Context) == SIF_None) {
4018         InitializationKind SubKind =
4019             Kind.getKind() == InitializationKind::IK_DirectList
4020                 ? InitializationKind::CreateDirect(Kind.getLocation(),
4021                                                    InitList->getLBraceLoc(),
4022                                                    InitList->getRBraceLoc())
4023                 : Kind;
4024         Sequence.InitializeFrom(S, Entity, SubKind, SubInit,
4025                                 /*TopLevelOfInitList*/ true,
4026                                 TreatUnavailableAsInvalid);
4027
4028         // TryStringLiteralInitialization() (in InitializeFrom()) will fail if
4029         // the element is not an appropriately-typed string literal, in which
4030         // case we should proceed as in C++11 (below).
4031         if (Sequence) {
4032           Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4033           return;
4034         }
4035       }
4036     }
4037   }
4038
4039   // C++11 [dcl.init.list]p3:
4040   //   - If T is an aggregate, aggregate initialization is performed.
4041   if ((DestType->isRecordType() && !DestType->isAggregateType()) ||
4042       (S.getLangOpts().CPlusPlus11 &&
4043        S.isStdInitializerList(DestType, nullptr))) {
4044     if (S.getLangOpts().CPlusPlus11) {
4045       //   - Otherwise, if the initializer list has no elements and T is a
4046       //     class type with a default constructor, the object is
4047       //     value-initialized.
4048       if (InitList->getNumInits() == 0) {
4049         CXXRecordDecl *RD = DestType->getAsCXXRecordDecl();
4050         if (RD->hasDefaultConstructor()) {
4051           TryValueInitialization(S, Entity, Kind, Sequence, InitList);
4052           return;
4053         }
4054       }
4055
4056       //   - Otherwise, if T is a specialization of std::initializer_list<E>,
4057       //     an initializer_list object constructed [...]
4058       if (TryInitializerListConstruction(S, InitList, DestType, Sequence,
4059                                          TreatUnavailableAsInvalid))
4060         return;
4061
4062       //   - Otherwise, if T is a class type, constructors are considered.
4063       Expr *InitListAsExpr = InitList;
4064       TryConstructorInitialization(S, Entity, Kind, InitListAsExpr, DestType,
4065                                    DestType, Sequence, /*InitListSyntax*/true);
4066     } else
4067       Sequence.SetFailed(InitializationSequence::FK_InitListBadDestinationType);
4068     return;
4069   }
4070
4071   if (S.getLangOpts().CPlusPlus && !DestType->isAggregateType() &&
4072       InitList->getNumInits() == 1) {
4073     Expr *E = InitList->getInit(0);
4074
4075     //   - Otherwise, if T is an enumeration with a fixed underlying type,
4076     //     the initializer-list has a single element v, and the initialization
4077     //     is direct-list-initialization, the object is initialized with the
4078     //     value T(v); if a narrowing conversion is required to convert v to
4079     //     the underlying type of T, the program is ill-formed.
4080     auto *ET = DestType->getAs<EnumType>();
4081     if (S.getLangOpts().CPlusPlus17 &&
4082         Kind.getKind() == InitializationKind::IK_DirectList &&
4083         ET && ET->getDecl()->isFixed() &&
4084         !S.Context.hasSameUnqualifiedType(E->getType(), DestType) &&
4085         (E->getType()->isIntegralOrEnumerationType() ||
4086          E->getType()->isFloatingType())) {
4087       // There are two ways that T(v) can work when T is an enumeration type.
4088       // If there is either an implicit conversion sequence from v to T or
4089       // a conversion function that can convert from v to T, then we use that.
4090       // Otherwise, if v is of integral, enumeration, or floating-point type,
4091       // it is converted to the enumeration type via its underlying type.
4092       // There is no overlap possible between these two cases (except when the
4093       // source value is already of the destination type), and the first
4094       // case is handled by the general case for single-element lists below.
4095       ImplicitConversionSequence ICS;
4096       ICS.setStandard();
4097       ICS.Standard.setAsIdentityConversion();
4098       if (!E->isRValue())
4099         ICS.Standard.First = ICK_Lvalue_To_Rvalue;
4100       // If E is of a floating-point type, then the conversion is ill-formed
4101       // due to narrowing, but go through the motions in order to produce the
4102       // right diagnostic.
4103       ICS.Standard.Second = E->getType()->isFloatingType()
4104                                 ? ICK_Floating_Integral
4105                                 : ICK_Integral_Conversion;
4106       ICS.Standard.setFromType(E->getType());
4107       ICS.Standard.setToType(0, E->getType());
4108       ICS.Standard.setToType(1, DestType);
4109       ICS.Standard.setToType(2, DestType);
4110       Sequence.AddConversionSequenceStep(ICS, ICS.Standard.getToType(2),
4111                                          /*TopLevelOfInitList*/true);
4112       Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4113       return;
4114     }
4115
4116     //   - Otherwise, if the initializer list has a single element of type E
4117     //     [...references are handled above...], the object or reference is
4118     //     initialized from that element (by copy-initialization for
4119     //     copy-list-initialization, or by direct-initialization for
4120     //     direct-list-initialization); if a narrowing conversion is required
4121     //     to convert the element to T, the program is ill-formed.
4122     //
4123     // Per core-24034, this is direct-initialization if we were performing
4124     // direct-list-initialization and copy-initialization otherwise.
4125     // We can't use InitListChecker for this, because it always performs
4126     // copy-initialization. This only matters if we might use an 'explicit'
4127     // conversion operator, so we only need to handle the cases where the source
4128     // is of record type.
4129     if (InitList->getInit(0)->getType()->isRecordType()) {
4130       InitializationKind SubKind =
4131           Kind.getKind() == InitializationKind::IK_DirectList
4132               ? InitializationKind::CreateDirect(Kind.getLocation(),
4133                                                  InitList->getLBraceLoc(),
4134                                                  InitList->getRBraceLoc())
4135               : Kind;
4136       Expr *SubInit[1] = { InitList->getInit(0) };
4137       Sequence.InitializeFrom(S, Entity, SubKind, SubInit,
4138                               /*TopLevelOfInitList*/true,
4139                               TreatUnavailableAsInvalid);
4140       if (Sequence)
4141         Sequence.RewrapReferenceInitList(Entity.getType(), InitList);
4142       return;
4143     }
4144   }
4145
4146   InitListChecker CheckInitList(S, Entity, InitList,
4147           DestType, /*VerifyOnly=*/true, TreatUnavailableAsInvalid);
4148   if (CheckInitList.HadError()) {
4149     Sequence.SetFailed(InitializationSequence::FK_ListInitializationFailed);
4150     return;
4151   }
4152
4153   // Add the list initialization step with the built init list.
4154   Sequence.AddListInitializationStep(DestType);
4155 }
4156
4157 /// \brief Try a reference initialization that involves calling a conversion
4158 /// function.
4159 static OverloadingResult TryRefInitWithConversionFunction(
4160     Sema &S, const InitializedEntity &Entity, const InitializationKind &Kind,
4161     Expr *Initializer, bool AllowRValues, bool IsLValueRef,
4162     InitializationSequence &Sequence) {
4163   QualType DestType = Entity.getType();
4164   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
4165   QualType T1 = cv1T1.getUnqualifiedType();
4166   QualType cv2T2 = Initializer->getType();
4167   QualType T2 = cv2T2.getUnqualifiedType();
4168
4169   bool DerivedToBase;
4170   bool ObjCConversion;
4171   bool ObjCLifetimeConversion;
4172   assert(!S.CompareReferenceRelationship(Initializer->getLocStart(),
4173                                          T1, T2, DerivedToBase,
4174                                          ObjCConversion,
4175                                          ObjCLifetimeConversion) &&
4176          "Must have incompatible references when binding via conversion");
4177   (void)DerivedToBase;
4178   (void)ObjCConversion;
4179   (void)ObjCLifetimeConversion;
4180
4181   // Build the candidate set directly in the initialization sequence
4182   // structure, so that it will persist if we fail.
4183   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
4184   CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
4185
4186   // Determine whether we are allowed to call explicit constructors or
4187   // explicit conversion operators.
4188   bool AllowExplicit = Kind.AllowExplicit();
4189   bool AllowExplicitConvs = Kind.allowExplicitConversionFunctionsInRefBinding();
4190
4191   const RecordType *T1RecordType = nullptr;
4192   if (AllowRValues && (T1RecordType = T1->getAs<RecordType>()) &&
4193       S.isCompleteType(Kind.getLocation(), T1)) {
4194     // The type we're converting to is a class type. Enumerate its constructors
4195     // to see if there is a suitable conversion.
4196     CXXRecordDecl *T1RecordDecl = cast<CXXRecordDecl>(T1RecordType->getDecl());
4197
4198     for (NamedDecl *D : S.LookupConstructors(T1RecordDecl)) {
4199       auto Info = getConstructorInfo(D);
4200       if (!Info.Constructor)
4201         continue;
4202
4203       if (!Info.Constructor->isInvalidDecl() &&
4204           Info.Constructor->isConvertingConstructor(AllowExplicit)) {
4205         if (Info.ConstructorTmpl)
4206           S.AddTemplateOverloadCandidate(Info.ConstructorTmpl, Info.FoundDecl,
4207                                          /*ExplicitArgs*/ nullptr,
4208                                          Initializer, CandidateSet,
4209                                          /*SuppressUserConversions=*/true);
4210         else
4211           S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl,
4212                                  Initializer, CandidateSet,
4213                                  /*SuppressUserConversions=*/true);
4214       }
4215     }
4216   }
4217   if (T1RecordType && T1RecordType->getDecl()->isInvalidDecl())
4218     return OR_No_Viable_Function;
4219
4220   const RecordType *T2RecordType = nullptr;
4221   if ((T2RecordType = T2->getAs<RecordType>()) &&
4222       S.isCompleteType(Kind.getLocation(), T2)) {
4223     // The type we're converting from is a class type, enumerate its conversion
4224     // functions.
4225     CXXRecordDecl *T2RecordDecl = cast<CXXRecordDecl>(T2RecordType->getDecl());
4226
4227     const auto &Conversions = T2RecordDecl->getVisibleConversionFunctions();
4228     for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
4229       NamedDecl *D = *I;
4230       CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
4231       if (isa<UsingShadowDecl>(D))
4232         D = cast<UsingShadowDecl>(D)->getTargetDecl();
4233
4234       FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
4235       CXXConversionDecl *Conv;
4236       if (ConvTemplate)
4237         Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
4238       else
4239         Conv = cast<CXXConversionDecl>(D);
4240
4241       // If the conversion function doesn't return a reference type,
4242       // it can't be considered for this conversion unless we're allowed to
4243       // consider rvalues.
4244       // FIXME: Do we need to make sure that we only consider conversion
4245       // candidates with reference-compatible results? That might be needed to
4246       // break recursion.
4247       if ((AllowExplicitConvs || !Conv->isExplicit()) &&
4248           (AllowRValues || Conv->getConversionType()->isLValueReferenceType())){
4249         if (ConvTemplate)
4250           S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(),
4251                                            ActingDC, Initializer,
4252                                            DestType, CandidateSet,
4253                                            /*AllowObjCConversionOnExplicit=*/
4254                                              false);
4255         else
4256           S.AddConversionCandidate(Conv, I.getPair(), ActingDC,
4257                                    Initializer, DestType, CandidateSet,
4258                                    /*AllowObjCConversionOnExplicit=*/false);
4259       }
4260     }
4261   }
4262   if (T2RecordType && T2RecordType->getDecl()->isInvalidDecl())
4263     return OR_No_Viable_Function;
4264
4265   SourceLocation DeclLoc = Initializer->getLocStart();
4266
4267   // Perform overload resolution. If it fails, return the failed result.
4268   OverloadCandidateSet::iterator Best;
4269   if (OverloadingResult Result
4270         = CandidateSet.BestViableFunction(S, DeclLoc, Best))
4271     return Result;
4272
4273   FunctionDecl *Function = Best->Function;
4274   // This is the overload that will be used for this initialization step if we
4275   // use this initialization. Mark it as referenced.
4276   Function->setReferenced();
4277
4278   // Compute the returned type and value kind of the conversion.
4279   QualType cv3T3;
4280   if (isa<CXXConversionDecl>(Function))
4281     cv3T3 = Function->getReturnType();
4282   else
4283     cv3T3 = T1;
4284
4285   ExprValueKind VK = VK_RValue;
4286   if (cv3T3->isLValueReferenceType())
4287     VK = VK_LValue;
4288   else if (const auto *RRef = cv3T3->getAs<RValueReferenceType>())
4289     VK = RRef->getPointeeType()->isFunctionType() ? VK_LValue : VK_XValue;
4290   cv3T3 = cv3T3.getNonLValueExprType(S.Context);
4291
4292   // Add the user-defined conversion step.
4293   bool HadMultipleCandidates = (CandidateSet.size() > 1);
4294   Sequence.AddUserConversionStep(Function, Best->FoundDecl, cv3T3,
4295                                  HadMultipleCandidates);
4296
4297   // Determine whether we'll need to perform derived-to-base adjustments or
4298   // other conversions.
4299   bool NewDerivedToBase = false;
4300   bool NewObjCConversion = false;
4301   bool NewObjCLifetimeConversion = false;
4302   Sema::ReferenceCompareResult NewRefRelationship
4303     = S.CompareReferenceRelationship(DeclLoc, T1, cv3T3,
4304                                      NewDerivedToBase, NewObjCConversion,
4305                                      NewObjCLifetimeConversion);
4306
4307   // Add the final conversion sequence, if necessary.
4308   if (NewRefRelationship == Sema::Ref_Incompatible) {
4309     assert(!isa<CXXConstructorDecl>(Function) &&
4310            "should not have conversion after constructor");
4311
4312     ImplicitConversionSequence ICS;
4313     ICS.setStandard();
4314     ICS.Standard = Best->FinalConversion;
4315     Sequence.AddConversionSequenceStep(ICS, ICS.Standard.getToType(2));
4316
4317     // Every implicit conversion results in a prvalue, except for a glvalue
4318     // derived-to-base conversion, which we handle below.
4319     cv3T3 = ICS.Standard.getToType(2);
4320     VK = VK_RValue;
4321   }
4322
4323   //   If the converted initializer is a prvalue, its type T4 is adjusted to
4324   //   type "cv1 T4" and the temporary materialization conversion is applied.
4325   //
4326   // We adjust the cv-qualifications to match the reference regardless of
4327   // whether we have a prvalue so that the AST records the change. In this
4328   // case, T4 is "cv3 T3".
4329   QualType cv1T4 = S.Context.getQualifiedType(cv3T3, cv1T1.getQualifiers());
4330   if (cv1T4.getQualifiers() != cv3T3.getQualifiers())
4331     Sequence.AddQualificationConversionStep(cv1T4, VK);
4332   Sequence.AddReferenceBindingStep(cv1T4, VK == VK_RValue);
4333   VK = IsLValueRef ? VK_LValue : VK_XValue;
4334
4335   if (NewDerivedToBase)
4336     Sequence.AddDerivedToBaseCastStep(cv1T1, VK);
4337   else if (NewObjCConversion)
4338     Sequence.AddObjCObjectConversionStep(cv1T1);
4339
4340   return OR_Success;
4341 }
4342
4343 static void CheckCXX98CompatAccessibleCopy(Sema &S,
4344                                            const InitializedEntity &Entity,
4345                                            Expr *CurInitExpr);
4346
4347 /// \brief Attempt reference initialization (C++0x [dcl.init.ref])
4348 static void TryReferenceInitialization(Sema &S,
4349                                        const InitializedEntity &Entity,
4350                                        const InitializationKind &Kind,
4351                                        Expr *Initializer,
4352                                        InitializationSequence &Sequence) {
4353   QualType DestType = Entity.getType();
4354   QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
4355   Qualifiers T1Quals;
4356   QualType T1 = S.Context.getUnqualifiedArrayType(cv1T1, T1Quals);
4357   QualType cv2T2 = Initializer->getType();
4358   Qualifiers T2Quals;
4359   QualType T2 = S.Context.getUnqualifiedArrayType(cv2T2, T2Quals);
4360
4361   // If the initializer is the address of an overloaded function, try
4362   // to resolve the overloaded function. If all goes well, T2 is the
4363   // type of the resulting function.
4364   if (ResolveOverloadedFunctionForReferenceBinding(S, Initializer, cv2T2, T2,
4365                                                    T1, Sequence))
4366     return;
4367
4368   // Delegate everything else to a subfunction.
4369   TryReferenceInitializationCore(S, Entity, Kind, Initializer, cv1T1, T1,
4370                                  T1Quals, cv2T2, T2, T2Quals, Sequence);
4371 }
4372
4373 /// Determine whether an expression is a non-referenceable glvalue (one to
4374 /// which a reference can never bind). Attemting to bind a reference to
4375 /// such a glvalue will always create a temporary.
4376 static bool isNonReferenceableGLValue(Expr *E) {
4377   return E->refersToBitField() || E->refersToVectorElement();
4378 }
4379
4380 /// \brief Reference initialization without resolving overloaded functions.
4381 static void TryReferenceInitializationCore(Sema &S,
4382                                            const InitializedEntity &Entity,
4383                                            const InitializationKind &Kind,
4384                                            Expr *Initializer,
4385                                            QualType cv1T1, QualType T1,
4386                                            Qualifiers T1Quals,
4387                                            QualType cv2T2, QualType T2,
4388                                            Qualifiers T2Quals,
4389                                            InitializationSequence &Sequence) {
4390   QualType DestType = Entity.getType();
4391   SourceLocation DeclLoc = Initializer->getLocStart();
4392   // Compute some basic properties of the types and the initializer.
4393   bool isLValueRef = DestType->isLValueReferenceType();
4394   bool isRValueRef = !isLValueRef;
4395   bool DerivedToBase = false;
4396   bool ObjCConversion = false;
4397   bool ObjCLifetimeConversion = false;
4398   Expr::Classification InitCategory = Initializer->Classify(S.Context);
4399   Sema::ReferenceCompareResult RefRelationship
4400     = S.CompareReferenceRelationship(DeclLoc, cv1T1, cv2T2, DerivedToBase,
4401                                      ObjCConversion, ObjCLifetimeConversion);
4402
4403   // C++0x [dcl.init.ref]p5:
4404   //   A reference to type "cv1 T1" is initialized by an expression of type
4405   //   "cv2 T2" as follows:
4406   //
4407   //     - If the reference is an lvalue reference and the initializer
4408   //       expression
4409   // Note the analogous bullet points for rvalue refs to functions. Because
4410   // there are no function rvalues in C++, rvalue refs to functions are treated
4411   // like lvalue refs.
4412   OverloadingResult ConvOvlResult = OR_Success;
4413   bool T1Function = T1->isFunctionType();
4414   if (isLValueRef || T1Function) {
4415     if (InitCategory.isLValue() && !isNonReferenceableGLValue(Initializer) &&
4416         (RefRelationship == Sema::Ref_Compatible ||
4417          (Kind.isCStyleOrFunctionalCast() &&
4418           RefRelationship == Sema::Ref_Related))) {
4419       //   - is an lvalue (but is not a bit-field), and "cv1 T1" is
4420       //     reference-compatible with "cv2 T2," or
4421       if (T1Quals != T2Quals)
4422         // Convert to cv1 T2. This should only add qualifiers unless this is a
4423         // c-style cast. The removal of qualifiers in that case notionally
4424         // happens after the reference binding, but that doesn't matter.
4425         Sequence.AddQualificationConversionStep(
4426             S.Context.getQualifiedType(T2, T1Quals),
4427             Initializer->getValueKind());
4428       if (DerivedToBase)
4429         Sequence.AddDerivedToBaseCastStep(cv1T1, VK_LValue);
4430       else if (ObjCConversion)
4431         Sequence.AddObjCObjectConversionStep(cv1T1);
4432
4433       // We only create a temporary here when binding a reference to a
4434       // bit-field or vector element. Those cases are't supposed to be
4435       // handled by this bullet, but the outcome is the same either way.
4436       Sequence.AddReferenceBindingStep(cv1T1, false);
4437       return;
4438     }
4439
4440     //     - has a class type (i.e., T2 is a class type), where T1 is not
4441     //       reference-related to T2, and can be implicitly converted to an
4442     //       lvalue of type "cv3 T3," where "cv1 T1" is reference-compatible
4443     //       with "cv3 T3" (this conversion is selected by enumerating the
4444     //       applicable conversion functions (13.3.1.6) and choosing the best
4445     //       one through overload resolution (13.3)),
4446     // If we have an rvalue ref to function type here, the rhs must be
4447     // an rvalue. DR1287 removed the "implicitly" here.
4448     if (RefRelationship == Sema::Ref_Incompatible && T2->isRecordType() &&
4449         (isLValueRef || InitCategory.isRValue())) {
4450       ConvOvlResult = TryRefInitWithConversionFunction(
4451           S, Entity, Kind, Initializer, /*AllowRValues*/ isRValueRef,
4452           /*IsLValueRef*/ isLValueRef, Sequence);
4453       if (ConvOvlResult == OR_Success)
4454         return;
4455       if (ConvOvlResult != OR_No_Viable_Function)
4456         Sequence.SetOverloadFailure(
4457             InitializationSequence::FK_ReferenceInitOverloadFailed,
4458             ConvOvlResult);
4459     }
4460   }
4461
4462   //     - Otherwise, the reference shall be an lvalue reference to a
4463   //       non-volatile const type (i.e., cv1 shall be const), or the reference
4464   //       shall be an rvalue reference.
4465   if (isLValueRef && !(T1Quals.hasConst() && !T1Quals.hasVolatile())) {
4466     if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy)
4467       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
4468     else if (ConvOvlResult && !Sequence.getFailedCandidateSet().empty())
4469       Sequence.SetOverloadFailure(
4470                         InitializationSequence::FK_ReferenceInitOverloadFailed,
4471                                   ConvOvlResult);
4472     else if (!InitCategory.isLValue())
4473       Sequence.SetFailed(
4474           InitializationSequence::FK_NonConstLValueReferenceBindingToTemporary);
4475     else {
4476       InitializationSequence::FailureKind FK;
4477       switch (RefRelationship) {
4478       case Sema::Ref_Compatible:
4479         if (Initializer->refersToBitField())
4480           FK = InitializationSequence::
4481               FK_NonConstLValueReferenceBindingToBitfield;
4482         else if (Initializer->refersToVectorElement())
4483           FK = InitializationSequence::
4484               FK_NonConstLValueReferenceBindingToVectorElement;
4485         else
4486           llvm_unreachable("unexpected kind of compatible initializer");
4487         break;
4488       case Sema::Ref_Related:
4489         FK = InitializationSequence::FK_ReferenceInitDropsQualifiers;
4490         break;
4491       case Sema::Ref_Incompatible:
4492         FK = InitializationSequence::
4493             FK_NonConstLValueReferenceBindingToUnrelated;
4494         break;
4495       }
4496       Sequence.SetFailed(FK);
4497     }
4498     return;
4499   }
4500
4501   //    - If the initializer expression
4502   //      - is an
4503   // [<=14] xvalue (but not a bit-field), class prvalue, array prvalue, or
4504   // [1z]   rvalue (but not a bit-field) or
4505   //        function lvalue and "cv1 T1" is reference-compatible with "cv2 T2"
4506   //
4507   // Note: functions are handled above and below rather than here...
4508   if (!T1Function &&
4509       (RefRelationship == Sema::Ref_Compatible ||
4510        (Kind.isCStyleOrFunctionalCast() &&
4511         RefRelationship == Sema::Ref_Related)) &&
4512       ((InitCategory.isXValue() && !isNonReferenceableGLValue(Initializer)) ||
4513        (InitCategory.isPRValue() &&
4514         (S.getLangOpts().CPlusPlus17 || T2->isRecordType() ||
4515          T2->isArrayType())))) {
4516     ExprValueKind ValueKind = InitCategory.isXValue() ? VK_XValue : VK_RValue;
4517     if (InitCategory.isPRValue() && T2->isRecordType()) {
4518       // The corresponding bullet in C++03 [dcl.init.ref]p5 gives the
4519       // compiler the freedom to perform a copy here or bind to the
4520       // object, while C++0x requires that we bind directly to the
4521       // object. Hence, we always bind to the object without making an
4522       // extra copy. However, in C++03 requires that we check for the
4523       // presence of a suitable copy constructor:
4524       //
4525       //   The constructor that would be used to make the copy shall
4526       //   be callable whether or not the copy is actually done.
4527       if (!S.getLangOpts().CPlusPlus11 && !S.getLangOpts().MicrosoftExt)
4528         Sequence.AddExtraneousCopyToTemporary(cv2T2);
4529       else if (S.getLangOpts().CPlusPlus11)
4530         CheckCXX98CompatAccessibleCopy(S, Entity, Initializer);
4531     }
4532
4533     // C++1z [dcl.init.ref]/5.2.1.2:
4534     //   If the converted initializer is a prvalue, its type T4 is adjusted
4535     //   to type "cv1 T4" and the temporary materialization conversion is
4536     //   applied.
4537     QualType cv1T4 = S.Context.getQualifiedType(cv2T2, T1Quals);
4538     if (T1Quals != T2Quals)
4539       Sequence.AddQualificationConversionStep(cv1T4, ValueKind);
4540     Sequence.AddReferenceBindingStep(cv1T4, ValueKind == VK_RValue);
4541     ValueKind = isLValueRef ? VK_LValue : VK_XValue;
4542
4543     //   In any case, the reference is bound to the resulting glvalue (or to
4544     //   an appropriate base class subobject).
4545     if (DerivedToBase)
4546       Sequence.AddDerivedToBaseCastStep(cv1T1, ValueKind);
4547     else if (ObjCConversion)
4548       Sequence.AddObjCObjectConversionStep(cv1T1);
4549     return;
4550   }
4551
4552   //       - has a class type (i.e., T2 is a class type), where T1 is not
4553   //         reference-related to T2, and can be implicitly converted to an
4554   //         xvalue, class prvalue, or function lvalue of type "cv3 T3",
4555   //         where "cv1 T1" is reference-compatible with "cv3 T3",
4556   //
4557   // DR1287 removes the "implicitly" here.
4558   if (T2->isRecordType()) {
4559     if (RefRelationship == Sema::Ref_Incompatible) {
4560       ConvOvlResult = TryRefInitWithConversionFunction(
4561           S, Entity, Kind, Initializer, /*AllowRValues*/ true,
4562           /*IsLValueRef*/ isLValueRef, Sequence);
4563       if (ConvOvlResult)
4564         Sequence.SetOverloadFailure(
4565             InitializationSequence::FK_ReferenceInitOverloadFailed,
4566             ConvOvlResult);
4567
4568       return;
4569     }
4570
4571     if (RefRelationship == Sema::Ref_Compatible &&
4572         isRValueRef && InitCategory.isLValue()) {
4573       Sequence.SetFailed(
4574         InitializationSequence::FK_RValueReferenceBindingToLValue);
4575       return;
4576     }
4577
4578     Sequence.SetFailed(InitializationSequence::FK_ReferenceInitDropsQualifiers);
4579     return;
4580   }
4581
4582   //      - Otherwise, a temporary of type "cv1 T1" is created and initialized
4583   //        from the initializer expression using the rules for a non-reference
4584   //        copy-initialization (8.5). The reference is then bound to the
4585   //        temporary. [...]
4586
4587   InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(cv1T1);
4588
4589   // FIXME: Why do we use an implicit conversion here rather than trying
4590   // copy-initialization?
4591   ImplicitConversionSequence ICS
4592     = S.TryImplicitConversion(Initializer, TempEntity.getType(),
4593                               /*SuppressUserConversions=*/false,
4594                               /*AllowExplicit=*/false,
4595                               /*FIXME:InOverloadResolution=*/false,
4596                               /*CStyle=*/Kind.isCStyleOrFunctionalCast(),
4597                               /*AllowObjCWritebackConversion=*/false);
4598
4599   if (ICS.isBad()) {
4600     // FIXME: Use the conversion function set stored in ICS to turn
4601     // this into an overloading ambiguity diagnostic. However, we need
4602     // to keep that set as an OverloadCandidateSet rather than as some
4603     // other kind of set.
4604     if (ConvOvlResult && !Sequence.getFailedCandidateSet().empty())
4605       Sequence.SetOverloadFailure(
4606                         InitializationSequence::FK_ReferenceInitOverloadFailed,
4607                                   ConvOvlResult);
4608     else if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy)
4609       Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
4610     else
4611       Sequence.SetFailed(InitializationSequence::FK_ReferenceInitFailed);
4612     return;
4613   } else {
4614     Sequence.AddConversionSequenceStep(ICS, TempEntity.getType());
4615   }
4616
4617   //        [...] If T1 is reference-related to T2, cv1 must be the
4618   //        same cv-qualification as, or greater cv-qualification
4619   //        than, cv2; otherwise, the program is ill-formed.
4620   unsigned T1CVRQuals = T1Quals.getCVRQualifiers();
4621   unsigned T2CVRQuals = T2Quals.getCVRQualifiers();
4622   if (RefRelationship == Sema::Ref_Related &&
4623       (T1CVRQuals | T2CVRQuals) != T1CVRQuals) {
4624     Sequence.SetFailed(InitializationSequence::FK_ReferenceInitDropsQualifiers);
4625     return;
4626   }
4627
4628   //   [...] If T1 is reference-related to T2 and the reference is an rvalue
4629   //   reference, the initializer expression shall not be an lvalue.
4630   if (RefRelationship >= Sema::Ref_Related && !isLValueRef &&
4631       InitCategory.isLValue()) {
4632     Sequence.SetFailed(
4633                     InitializationSequence::FK_RValueReferenceBindingToLValue);
4634     return;
4635   }
4636
4637   Sequence.AddReferenceBindingStep(cv1T1, /*bindingTemporary=*/true);
4638 }
4639
4640 /// \brief Attempt character array initialization from a string literal
4641 /// (C++ [dcl.init.string], C99 6.7.8).
4642 static void TryStringLiteralInitialization(Sema &S,
4643                                            const InitializedEntity &Entity,
4644                                            const InitializationKind &Kind,
4645                                            Expr *Initializer,
4646                                        InitializationSequence &Sequence) {
4647   Sequence.AddStringInitStep(Entity.getType());
4648 }
4649
4650 /// \brief Attempt value initialization (C++ [dcl.init]p7).
4651 static void TryValueInitialization(Sema &S,
4652                                    const InitializedEntity &Entity,
4653                                    const InitializationKind &Kind,
4654                                    InitializationSequence &Sequence,
4655                                    InitListExpr *InitList) {
4656   assert((!InitList || InitList->getNumInits() == 0) &&
4657          "Shouldn't use value-init for non-empty init lists");
4658
4659   // C++98 [dcl.init]p5, C++11 [dcl.init]p7:
4660   //
4661   //   To value-initialize an object of type T means:
4662   QualType T = Entity.getType();
4663
4664   //     -- if T is an array type, then each element is value-initialized;
4665   T = S.Context.getBaseElementType(T);
4666
4667   if (const RecordType *RT = T->getAs<RecordType>()) {
4668     if (CXXRecordDecl *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
4669       bool NeedZeroInitialization = true;
4670       // C++98:
4671       // -- if T is a class type (clause 9) with a user-declared constructor
4672       //    (12.1), then the default constructor for T is called (and the
4673       //    initialization is ill-formed if T has no accessible default
4674       //    constructor);
4675       // C++11:
4676       // -- if T is a class type (clause 9) with either no default constructor
4677       //    (12.1 [class.ctor]) or a default constructor that is user-provided
4678       //    or deleted, then the object is default-initialized;
4679       //
4680       // Note that the C++11 rule is the same as the C++98 rule if there are no
4681       // defaulted or deleted constructors, so we just use it unconditionally.
4682       CXXConstructorDecl *CD = S.LookupDefaultConstructor(ClassDecl);
4683       if (!CD || !CD->getCanonicalDecl()->isDefaulted() || CD->isDeleted())
4684         NeedZeroInitialization = false;
4685
4686       // -- if T is a (possibly cv-qualified) non-union class type without a
4687       //    user-provided or deleted default constructor, then the object is
4688       //    zero-initialized and, if T has a non-trivial default constructor,
4689       //    default-initialized;
4690       // The 'non-union' here was removed by DR1502. The 'non-trivial default
4691       // constructor' part was removed by DR1507.
4692       if (NeedZeroInitialization)
4693         Sequence.AddZeroInitializationStep(Entity.getType());
4694
4695       // C++03:
4696       // -- if T is a non-union class type without a user-declared constructor,
4697       //    then every non-static data member and base class component of T is
4698       //    value-initialized;
4699       // [...] A program that calls for [...] value-initialization of an
4700       // entity of reference type is ill-formed.
4701       //
4702       // C++11 doesn't need this handling, because value-initialization does not
4703       // occur recursively there, and the implicit default constructor is
4704       // defined as deleted in the problematic cases.
4705       if (!S.getLangOpts().CPlusPlus11 &&
4706           ClassDecl->hasUninitializedReferenceMember()) {
4707         Sequence.SetFailed(InitializationSequence::FK_TooManyInitsForReference);
4708         return;
4709       }
4710
4711       // If this is list-value-initialization, pass the empty init list on when
4712       // building the constructor call. This affects the semantics of a few
4713       // things (such as whether an explicit default constructor can be called).
4714       Expr *InitListAsExpr = InitList;
4715       MultiExprArg Args(&InitListAsExpr, InitList ? 1 : 0);
4716       bool InitListSyntax = InitList;
4717
4718       // FIXME: Instead of creating a CXXConstructExpr of array type here,
4719       // wrap a class-typed CXXConstructExpr in an ArrayInitLoopExpr.
4720       return TryConstructorInitialization(
4721           S, Entity, Kind, Args, T, Entity.getType(), Sequence, InitListSyntax);
4722     }
4723   }
4724
4725   Sequence.AddZeroInitializationStep(Entity.getType());
4726 }
4727
4728 /// \brief Attempt default initialization (C++ [dcl.init]p6).
4729 static void TryDefaultInitialization(Sema &S,
4730                                      const InitializedEntity &Entity,
4731                                      const InitializationKind &Kind,
4732                                      InitializationSequence &Sequence) {
4733   assert(Kind.getKind() == InitializationKind::IK_Default);
4734
4735   // C++ [dcl.init]p6:
4736   //   To default-initialize an object of type T means:
4737   //     - if T is an array type, each element is default-initialized;
4738   QualType DestType = S.Context.getBaseElementType(Entity.getType());
4739
4740   //     - if T is a (possibly cv-qualified) class type (Clause 9), the default
4741   //       constructor for T is called (and the initialization is ill-formed if
4742   //       T has no accessible default constructor);
4743   if (DestType->isRecordType() && S.getLangOpts().CPlusPlus) {
4744     TryConstructorInitialization(S, Entity, Kind, None, DestType,
4745                                  Entity.getType(), Sequence);
4746     return;
4747   }
4748
4749   //     - otherwise, no initialization is performed.
4750
4751   //   If a program calls for the default initialization of an object of
4752   //   a const-qualified type T, T shall be a class type with a user-provided
4753   //   default constructor.
4754   if (DestType.isConstQualified() && S.getLangOpts().CPlusPlus) {
4755     if (!maybeRecoverWithZeroInitialization(S, Sequence, Entity))
4756       Sequence.SetFailed(InitializationSequence::FK_DefaultInitOfConst);
4757     return;
4758   }
4759
4760   // If the destination type has a lifetime property, zero-initialize it.
4761   if (DestType.getQualifiers().hasObjCLifetime()) {
4762     Sequence.AddZeroInitializationStep(Entity.getType());
4763     return;
4764   }
4765 }
4766
4767 /// \brief Attempt a user-defined conversion between two types (C++ [dcl.init]),
4768 /// which enumerates all conversion functions and performs overload resolution
4769 /// to select the best.
4770 static void TryUserDefinedConversion(Sema &S,
4771                                      QualType DestType,
4772                                      const InitializationKind &Kind,
4773                                      Expr *Initializer,
4774                                      InitializationSequence &Sequence,
4775                                      bool TopLevelOfInitList) {
4776   assert(!DestType->isReferenceType() && "References are handled elsewhere");
4777   QualType SourceType = Initializer->getType();
4778   assert((DestType->isRecordType() || SourceType->isRecordType()) &&
4779          "Must have a class type to perform a user-defined conversion");
4780
4781   // Build the candidate set directly in the initialization sequence
4782   // structure, so that it will persist if we fail.
4783   OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
4784   CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
4785
4786   // Determine whether we are allowed to call explicit constructors or
4787   // explicit conversion operators.
4788   bool AllowExplicit = Kind.AllowExplicit();
4789
4790   if (const RecordType *DestRecordType = DestType->getAs<RecordType>()) {
4791     // The type we're converting to is a class type. Enumerate its constructors
4792     // to see if there is a suitable conversion.
4793     CXXRecordDecl *DestRecordDecl
4794       = cast<CXXRecordDecl>(DestRecordType->getDecl());
4795
4796     // Try to complete the type we're converting to.
4797     if (S.isCompleteType(Kind.getLocation(), DestType)) {
4798       for (NamedDecl *D : S.LookupConstructors(DestRecordDecl)) {
4799         auto Info = getConstructorInfo(D);
4800         if (!Info.Constructor)
4801           continue;
4802
4803         if (!Info.Constructor->isInvalidDecl() &&
4804             Info.Constructor->isConvertingConstructor(AllowExplicit)) {
4805           if (Info.ConstructorTmpl)
4806             S.AddTemplateOverloadCandidate(Info.ConstructorTmpl, Info.FoundDecl,
4807                                            /*ExplicitArgs*/ nullptr,
4808                                            Initializer, CandidateSet,
4809                                            /*SuppressUserConversions=*/true);
4810           else
4811             S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl,
4812                                    Initializer, CandidateSet,
4813                                    /*SuppressUserConversions=*/true);
4814         }
4815       }
4816     }
4817   }
4818
4819   SourceLocation DeclLoc = Initializer->getLocStart();
4820
4821   if (const RecordType *SourceRecordType = SourceType->getAs<RecordType>()) {
4822     // The type we're converting from is a class type, enumerate its conversion
4823     // functions.
4824
4825     // We can only enumerate the conversion functions for a complete type; if
4826     // the type isn't complete, simply skip this step.
4827     if (S.isCompleteType(DeclLoc, SourceType)) {
4828       CXXRecordDecl *SourceRecordDecl
4829         = cast<CXXRecordDecl>(SourceRecordType->getDecl());
4830
4831       const auto &Conversions =
4832           SourceRecordDecl->getVisibleConversionFunctions();
4833       for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
4834         NamedDecl *D = *I;
4835         CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
4836         if (isa<UsingShadowDecl>(D))
4837           D = cast<UsingShadowDecl>(D)->getTargetDecl();
4838
4839         FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
4840         CXXConversionDecl *Conv;
4841         if (ConvTemplate)
4842           Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
4843         else
4844           Conv = cast<CXXConversionDecl>(D);
4845
4846         if (AllowExplicit || !Conv->isExplicit()) {
4847           if (ConvTemplate)
4848             S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(),
4849                                              ActingDC, Initializer, DestType,
4850                                              CandidateSet, AllowExplicit);
4851           else
4852             S.AddConversionCandidate(Conv, I.getPair(), ActingDC,
4853                                      Initializer, DestType, CandidateSet,
4854                                      AllowExplicit);
4855         }
4856       }
4857     }
4858   }
4859
4860   // Perform overload resolution. If it fails, return the failed result.
4861   OverloadCandidateSet::iterator Best;
4862   if (OverloadingResult Result
4863         = CandidateSet.BestViableFunction(S, DeclLoc, Best)) {
4864     Sequence.SetOverloadFailure(
4865                         InitializationSequence::FK_UserConversionOverloadFailed,
4866                                 Result);
4867     return;
4868   }
4869
4870   FunctionDecl *Function = Best->Function;
4871   Function->setReferenced();
4872   bool HadMultipleCandidates = (CandidateSet.size() > 1);
4873
4874   if (isa<CXXConstructorDecl>(Function)) {
4875     // Add the user-defined conversion step. Any cv-qualification conversion is
4876     // subsumed by the initialization. Per DR5, the created temporary is of the
4877     // cv-unqualified type of the destination.
4878     Sequence.AddUserConversionStep(Function, Best->FoundDecl,
4879                                    DestType.getUnqualifiedType(),
4880                                    HadMultipleCandidates);
4881
4882     // C++14 and before:
4883     //   - if the function is a constructor, the call initializes a temporary
4884     //     of the cv-unqualified version of the destination type. The [...]
4885     //     temporary [...] is then used to direct-initialize, according to the
4886     //     rules above, the object that is the destination of the
4887     //     copy-initialization.
4888     // Note that this just performs a simple object copy from the temporary.
4889     //
4890     // C++17:
4891     //   - if the function is a constructor, the call is a prvalue of the
4892     //     cv-unqualified version of the destination type whose return object
4893     //     is initialized by the constructor. The call is used to
4894     //     direct-initialize, according to the rules above, the object that
4895     //     is the destination of the copy-initialization.
4896     // Therefore we need to do nothing further.
4897     //
4898     // FIXME: Mark this copy as extraneous.
4899     if (!S.getLangOpts().CPlusPlus17)
4900       Sequence.AddFinalCopy(DestType);
4901     else if (DestType.hasQualifiers())
4902       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
4903     return;
4904   }
4905
4906   // Add the user-defined conversion step that calls the conversion function.
4907   QualType ConvType = Function->getCallResultType();
4908   Sequence.AddUserConversionStep(Function, Best->FoundDecl, ConvType,
4909                                  HadMultipleCandidates);
4910
4911   if (ConvType->getAs<RecordType>()) {
4912     //   The call is used to direct-initialize [...] the object that is the
4913     //   destination of the copy-initialization.
4914     //
4915     // In C++17, this does not call a constructor if we enter /17.6.1:
4916     //   - If the initializer expression is a prvalue and the cv-unqualified
4917     //     version of the source type is the same as the class of the
4918     //     destination [... do not make an extra copy]
4919     //
4920     // FIXME: Mark this copy as extraneous.
4921     if (!S.getLangOpts().CPlusPlus17 ||
4922         Function->getReturnType()->isReferenceType() ||
4923         !S.Context.hasSameUnqualifiedType(ConvType, DestType))
4924       Sequence.AddFinalCopy(DestType);
4925     else if (!S.Context.hasSameType(ConvType, DestType))
4926       Sequence.AddQualificationConversionStep(DestType, VK_RValue);
4927     return;
4928   }
4929
4930   // If the conversion following the call to the conversion function
4931   // is interesting, add it as a separate step.
4932   if (Best->FinalConversion.First || Best->FinalConversion.Second ||
4933       Best->FinalConversion.Third) {
4934     ImplicitConversionSequence ICS;
4935     ICS.setStandard();
4936     ICS.Standard = Best->FinalConversion;
4937     Sequence.AddConversionSequenceStep(ICS, DestType, TopLevelOfInitList);
4938   }
4939 }
4940
4941 /// An egregious hack for compatibility with libstdc++-4.2: in <tr1/hashtable>,
4942 /// a function with a pointer return type contains a 'return false;' statement.
4943 /// In C++11, 'false' is not a null pointer, so this breaks the build of any
4944 /// code using that header.
4945 ///
4946 /// Work around this by treating 'return false;' as zero-initializing the result
4947 /// if it's used in a pointer-returning function in a system header.
4948 static bool isLibstdcxxPointerReturnFalseHack(Sema &S,
4949                                               const InitializedEntity &Entity,
4950                                               const Expr *Init) {
4951   return S.getLangOpts().CPlusPlus11 &&
4952          Entity.getKind() == InitializedEntity::EK_Result &&
4953          Entity.getType()->isPointerType() &&
4954          isa<CXXBoolLiteralExpr>(Init) &&
4955          !cast<CXXBoolLiteralExpr>(Init)->getValue() &&
4956          S.getSourceManager().isInSystemHeader(Init->getExprLoc());
4957 }
4958
4959 /// The non-zero enum values here are indexes into diagnostic alternatives.
4960 enum InvalidICRKind { IIK_okay, IIK_nonlocal, IIK_nonscalar };
4961
4962 /// Determines whether this expression is an acceptable ICR source.
4963 static InvalidICRKind isInvalidICRSource(ASTContext &C, Expr *e,
4964                                          bool isAddressOf, bool &isWeakAccess) {
4965   // Skip parens.
4966   e = e->IgnoreParens();
4967
4968   // Skip address-of nodes.
4969   if (UnaryOperator *op = dyn_cast<UnaryOperator>(e)) {
4970     if (op->getOpcode() == UO_AddrOf)
4971       return isInvalidICRSource(C, op->getSubExpr(), /*addressof*/ true,
4972                                 isWeakAccess);
4973
4974   // Skip certain casts.
4975   } else if (CastExpr *ce = dyn_cast<CastExpr>(e)) {
4976     switch (ce->getCastKind()) {
4977     case CK_Dependent:
4978     case CK_BitCast:
4979     case CK_LValueBitCast:
4980     case CK_NoOp:
4981       return isInvalidICRSource(C, ce->getSubExpr(), isAddressOf, isWeakAccess);
4982
4983     case CK_ArrayToPointerDecay:
4984       return IIK_nonscalar;
4985
4986     case CK_NullToPointer:
4987       return IIK_okay;
4988
4989     default:
4990       break;
4991     }
4992
4993   // If we have a declaration reference, it had better be a local variable.
4994   } else if (isa<DeclRefExpr>(e)) {
4995     // set isWeakAccess to true, to mean that there will be an implicit
4996     // load which requires a cleanup.
4997     if (e->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
4998       isWeakAccess = true;
4999
5000     if (!isAddressOf) return IIK_nonlocal;
5001
5002     VarDecl *var = dyn_cast<VarDecl>(cast<DeclRefExpr>(e)->getDecl());
5003     if (!var) return IIK_nonlocal;
5004
5005     return (var->hasLocalStorage() ? IIK_okay : IIK_nonlocal);
5006
5007   // If we have a conditional operator, check both sides.
5008   } else if (ConditionalOperator *cond = dyn_cast<ConditionalOperator>(e)) {
5009     if (InvalidICRKind iik = isInvalidICRSource(C, cond->getLHS(), isAddressOf,
5010                                                 isWeakAccess))
5011       return iik;
5012
5013     return isInvalidICRSource(C, cond->getRHS(), isAddressOf, isWeakAccess);
5014
5015   // These are never scalar.
5016   } else if (isa<ArraySubscriptExpr>(e)) {
5017     return IIK_nonscalar;
5018
5019   // Otherwise, it needs to be a null pointer constant.
5020   } else {
5021     return (e->isNullPointerConstant(C, Expr::NPC_ValueDependentIsNull)
5022             ? IIK_okay : IIK_nonlocal);
5023   }
5024
5025   return IIK_nonlocal;
5026 }
5027
5028 /// Check whether the given expression is a valid operand for an
5029 /// indirect copy/restore.
5030 static void checkIndirectCopyRestoreSource(Sema &S, Expr *src) {
5031   assert(src->isRValue());
5032   bool isWeakAccess = false;
5033   InvalidICRKind iik = isInvalidICRSource(S.Context, src, false, isWeakAccess);
5034   // If isWeakAccess to true, there will be an implicit
5035   // load which requires a cleanup.
5036   if (S.getLangOpts().ObjCAutoRefCount && isWeakAccess)
5037     S.Cleanup.setExprNeedsCleanups(true);
5038
5039   if (iik == IIK_okay) return;
5040
5041   S.Diag(src->getExprLoc(), diag::err_arc_nonlocal_writeback)
5042     << ((unsigned) iik - 1)  // shift index into diagnostic explanations
5043     << src->getSourceRange();
5044 }
5045
5046 /// \brief Determine whether we have compatible array types for the
5047 /// purposes of GNU by-copy array initialization.
5048 static bool hasCompatibleArrayTypes(ASTContext &Context, const ArrayType *Dest,
5049                                     const ArrayType *Source) {
5050   // If the source and destination array types are equivalent, we're
5051   // done.
5052   if (Context.hasSameType(QualType(Dest, 0), QualType(Source, 0)))
5053     return true;
5054
5055   // Make sure that the element types are the same.
5056   if (!Context.hasSameType(Dest->getElementType(), Source->getElementType()))
5057     return false;
5058
5059   // The only mismatch we allow is when the destination is an
5060   // incomplete array type and the source is a constant array type.
5061   return Source->isConstantArrayType() && Dest->isIncompleteArrayType();
5062 }
5063
5064 static bool tryObjCWritebackConversion(Sema &S,
5065                                        InitializationSequence &Sequence,
5066                                        const InitializedEntity &Entity,
5067                                        Expr *Initializer) {
5068   bool ArrayDecay = false;
5069   QualType ArgType = Initializer->getType();
5070   QualType ArgPointee;
5071   if (const ArrayType *ArgArrayType = S.Context.getAsArrayType(ArgType)) {
5072     ArrayDecay = true;
5073     ArgPointee = ArgArrayType->getElementType();
5074     ArgType = S.Context.getPointerType(ArgPointee);
5075   }
5076
5077   // Handle write-back conversion.
5078   QualType ConvertedArgType;
5079   if (!S.isObjCWritebackConversion(ArgType, Entity.getType(),
5080                                    ConvertedArgType))
5081     return false;
5082
5083   // We should copy unless we're passing to an argument explicitly
5084   // marked 'out'.
5085   bool ShouldCopy = true;
5086   if (ParmVarDecl *param = cast_or_null<ParmVarDecl>(Entity.getDecl()))
5087     ShouldCopy = (param->getObjCDeclQualifier() != ParmVarDecl::OBJC_TQ_Out);
5088
5089   // Do we need an lvalue conversion?
5090   if (ArrayDecay || Initializer->isGLValue()) {
5091     ImplicitConversionSequence ICS;
5092     ICS.setStandard();
5093     ICS.Standard.setAsIdentityConversion();
5094
5095     QualType ResultType;
5096     if (ArrayDecay) {
5097       ICS.Standard.First = ICK_Array_To_Pointer;
5098       ResultType = S.Context.getPointerType(ArgPointee);
5099     } else {
5100       ICS.Standard.First = ICK_Lvalue_To_Rvalue;
5101       ResultType = Initializer->getType().getNonLValueExprType(S.Context);
5102     }
5103
5104     Sequence.AddConversionSequenceStep(ICS, ResultType);
5105   }
5106
5107   Sequence.AddPassByIndirectCopyRestoreStep(Entity.getType(), ShouldCopy);
5108   return true;
5109 }
5110
5111 static bool TryOCLSamplerInitialization(Sema &S,
5112                                         InitializationSequence &Sequence,
5113                                         QualType DestType,
5114                                         Expr *Initializer) {
5115   if (!S.getLangOpts().OpenCL || !DestType->isSamplerT() ||
5116       (!Initializer->isIntegerConstantExpr(S.Context) &&
5117       !Initializer->getType()->isSamplerT()))
5118     return false;
5119
5120   Sequence.AddOCLSamplerInitStep(DestType);
5121   return true;
5122 }
5123
5124 //
5125 // OpenCL 1.2 spec, s6.12.10
5126 //
5127 // The event argument can also be used to associate the
5128 // async_work_group_copy with a previous async copy allowing
5129 // an event to be shared by multiple async copies; otherwise
5130 // event should be zero.
5131 //
5132 static bool TryOCLZeroEventInitialization(Sema &S,
5133                                           InitializationSequence &Sequence,
5134                                           QualType DestType,
5135                                           Expr *Initializer) {
5136   if (!S.getLangOpts().OpenCL || !DestType->isEventT() ||
5137       !Initializer->isIntegerConstantExpr(S.getASTContext()) ||
5138       (Initializer->EvaluateKnownConstInt(S.getASTContext()) != 0))
5139     return false;
5140
5141   Sequence.AddOCLZeroEventStep(DestType);
5142   return true;
5143 }
5144
5145 static bool TryOCLZeroQueueInitialization(Sema &S,
5146                                           InitializationSequence &Sequence,
5147                                           QualType DestType,
5148                                           Expr *Initializer) {
5149   if (!S.getLangOpts().OpenCL || S.getLangOpts().OpenCLVersion < 200 ||
5150       !DestType->isQueueT() ||
5151       !Initializer->isIntegerConstantExpr(S.getASTContext()) ||
5152       (Initializer->EvaluateKnownConstInt(S.getASTContext()) != 0))
5153     return false;
5154
5155   Sequence.AddOCLZeroQueueStep(DestType);
5156   return true;
5157 }
5158
5159 InitializationSequence::InitializationSequence(Sema &S,
5160                                                const InitializedEntity &Entity,
5161                                                const InitializationKind &Kind,
5162                                                MultiExprArg Args,
5163                                                bool TopLevelOfInitList,
5164                                                bool TreatUnavailableAsInvalid)
5165     : FailedCandidateSet(Kind.getLocation(), OverloadCandidateSet::CSK_Normal) {
5166   InitializeFrom(S, Entity, Kind, Args, TopLevelOfInitList,
5167                  TreatUnavailableAsInvalid);
5168 }
5169
5170 /// Tries to get a FunctionDecl out of `E`. If it succeeds and we can take the
5171 /// address of that function, this returns true. Otherwise, it returns false.
5172 static bool isExprAnUnaddressableFunction(Sema &S, const Expr *E) {
5173   auto *DRE = dyn_cast<DeclRefExpr>(E);
5174   if (!DRE || !isa<FunctionDecl>(DRE->getDecl()))
5175     return false;
5176
5177   return !S.checkAddressOfFunctionIsAvailable(
5178       cast<FunctionDecl>(DRE->getDecl()));
5179 }
5180
5181 /// Determine whether we can perform an elementwise array copy for this kind
5182 /// of entity.
5183 static bool canPerformArrayCopy(const InitializedEntity &Entity) {
5184   switch (Entity.getKind()) {
5185   case InitializedEntity::EK_LambdaCapture:
5186     // C++ [expr.prim.lambda]p24:
5187     //   For array members, the array elements are direct-initialized in
5188     //   increasing subscript order.
5189     return true;
5190
5191   case InitializedEntity::EK_Variable:
5192     // C++ [dcl.decomp]p1:
5193     //   [...] each element is copy-initialized or direct-initialized from the
5194     //   corresponding element of the assignment-expression [...]
5195     return isa<DecompositionDecl>(Entity.getDecl());
5196
5197   case InitializedEntity::EK_Member:
5198     // C++ [class.copy.ctor]p14:
5199     //   - if the member is an array, each element is direct-initialized with
5200     //     the corresponding subobject of x
5201     return Entity.isImplicitMemberInitializer();
5202
5203   case InitializedEntity::EK_ArrayElement:
5204     // All the above cases are intended to apply recursively, even though none
5205     // of them actually say that.
5206     if (auto *E = Entity.getParent())
5207       return canPerformArrayCopy(*E);
5208     break;
5209
5210   default:
5211     break;
5212   }
5213
5214   return false;
5215 }
5216
5217 void InitializationSequence::InitializeFrom(Sema &S,
5218                                             const InitializedEntity &Entity,
5219                                             const InitializationKind &Kind,
5220                                             MultiExprArg Args,
5221                                             bool TopLevelOfInitList,
5222                                             bool TreatUnavailableAsInvalid) {
5223   ASTContext &Context = S.Context;
5224
5225   // Eliminate non-overload placeholder types in the arguments.  We
5226   // need to do this before checking whether types are dependent
5227   // because lowering a pseudo-object expression might well give us
5228   // something of dependent type.
5229   for (unsigned I = 0, E = Args.size(); I != E; ++I)
5230     if (Args[I]->getType()->isNonOverloadPlaceholderType()) {
5231       // FIXME: should we be doing this here?
5232       ExprResult result = S.CheckPlaceholderExpr(Args[I]);
5233       if (result.isInvalid()) {
5234         SetFailed(FK_PlaceholderType);
5235         return;
5236       }
5237       Args[I] = result.get();
5238     }
5239
5240   // C++0x [dcl.init]p16:
5241   //   The semantics of initializers are as follows. The destination type is
5242   //   the type of the object or reference being initialized and the source
5243   //   type is the type of the initializer expression. The source type is not
5244   //   defined when the initializer is a braced-init-list or when it is a
5245   //   parenthesized list of expressions.
5246   QualType DestType = Entity.getType();
5247
5248   if (DestType->isDependentType() ||
5249       Expr::hasAnyTypeDependentArguments(Args)) {
5250     SequenceKind = DependentSequence;
5251     return;
5252   }
5253
5254   // Almost everything is a normal sequence.
5255   setSequenceKind(NormalSequence);
5256
5257   QualType SourceType;
5258   Expr *Initializer = nullptr;
5259   if (Args.size() == 1) {
5260     Initializer = Args[0];
5261     if (S.getLangOpts().ObjC1) {
5262       if (S.CheckObjCBridgeRelatedConversions(Initializer->getLocStart(),
5263                                               DestType, Initializer->getType(),
5264                                               Initializer) ||
5265           S.ConversionToObjCStringLiteralCheck(DestType, Initializer))
5266         Args[0] = Initializer;
5267     }
5268     if (!isa<InitListExpr>(Initializer))
5269       SourceType = Initializer->getType();
5270   }
5271
5272   //     - If the initializer is a (non-parenthesized) braced-init-list, the
5273   //       object is list-initialized (8.5.4).
5274   if (Kind.getKind() != InitializationKind::IK_Direct) {
5275     if (InitListExpr *InitList = dyn_cast_or_null<InitListExpr>(Initializer)) {
5276       TryListInitialization(S, Entity, Kind, InitList, *this,
5277                             TreatUnavailableAsInvalid);
5278       return;
5279     }
5280   }
5281
5282   //     - If the destination type is a reference type, see 8.5.3.
5283   if (DestType->isReferenceType()) {
5284     // C++0x [dcl.init.ref]p1:
5285     //   A variable declared to be a T& or T&&, that is, "reference to type T"
5286     //   (8.3.2), shall be initialized by an object, or function, of type T or
5287     //   by an object that can be converted into a T.
5288     // (Therefore, multiple arguments are not permitted.)
5289     if (Args.size() != 1)
5290       SetFailed(FK_TooManyInitsForReference);
5291     // C++17 [dcl.init.ref]p5:
5292     //   A reference [...] is initialized by an expression [...] as follows:
5293     // If the initializer is not an expression, presumably we should reject,
5294     // but the standard fails to actually say so.
5295     else if (isa<InitListExpr>(Args[0]))
5296       SetFailed(FK_ParenthesizedListInitForReference);
5297     else
5298       TryReferenceInitialization(S, Entity, Kind, Args[0], *this);
5299     return;
5300   }
5301
5302   //     - If the initializer is (), the object is value-initialized.
5303   if (Kind.getKind() == InitializationKind::IK_Value ||
5304       (Kind.getKind() == InitializationKind::IK_Direct && Args.empty())) {
5305     TryValueInitialization(S, Entity, Kind, *this);
5306     return;
5307   }
5308
5309   // Handle default initialization.
5310   if (Kind.getKind() == InitializationKind::IK_Default) {
5311     TryDefaultInitialization(S, Entity, Kind, *this);
5312     return;
5313   }
5314
5315   //     - If the destination type is an array of characters, an array of
5316   //       char16_t, an array of char32_t, or an array of wchar_t, and the
5317   //       initializer is a string literal, see 8.5.2.
5318   //     - Otherwise, if the destination type is an array, the program is
5319   //       ill-formed.
5320   if (const ArrayType *DestAT = Context.getAsArrayType(DestType)) {
5321     if (Initializer && isa<VariableArrayType>(DestAT)) {
5322       SetFailed(FK_VariableLengthArrayHasInitializer);
5323       return;
5324     }
5325
5326     if (Initializer) {
5327       switch (IsStringInit(Initializer, DestAT, Context)) {
5328       case SIF_None:
5329         TryStringLiteralInitialization(S, Entity, Kind, Initializer, *this);
5330         return;
5331       case SIF_NarrowStringIntoWideChar:
5332         SetFailed(FK_NarrowStringIntoWideCharArray);
5333         return;
5334       case SIF_WideStringIntoChar:
5335         SetFailed(FK_WideStringIntoCharArray);
5336         return;
5337       case SIF_IncompatWideStringIntoWideChar:
5338         SetFailed(FK_IncompatWideStringIntoWideChar);
5339         return;
5340       case SIF_Other:
5341         break;
5342       }
5343     }
5344
5345     // Some kinds of initialization permit an array to be initialized from
5346     // another array of the same type, and perform elementwise initialization.
5347     if (Initializer && isa<ConstantArrayType>(DestAT) &&
5348         S.Context.hasSameUnqualifiedType(Initializer->getType(),
5349                                          Entity.getType()) &&
5350         canPerformArrayCopy(Entity)) {
5351       // If source is a prvalue, use it directly.
5352       if (Initializer->getValueKind() == VK_RValue) {
5353         AddArrayInitStep(DestType, /*IsGNUExtension*/false);
5354         return;
5355       }
5356
5357       // Emit element-at-a-time copy loop.
5358       InitializedEntity Element =
5359           InitializedEntity::InitializeElement(S.Context, 0, Entity);
5360       QualType InitEltT =
5361           Context.getAsArrayType(Initializer->getType())->getElementType();
5362       OpaqueValueExpr OVE(Initializer->getExprLoc(), InitEltT,
5363                           Initializer->getValueKind(),
5364                           Initializer->getObjectKind());
5365       Expr *OVEAsExpr = &OVE;
5366       InitializeFrom(S, Element, Kind, OVEAsExpr, TopLevelOfInitList,
5367                      TreatUnavailableAsInvalid);
5368       if (!Failed())
5369         AddArrayInitLoopStep(Entity.getType(), InitEltT);
5370       return;
5371     }
5372
5373     // Note: as an GNU C extension, we allow initialization of an
5374     // array from a compound literal that creates an array of the same
5375     // type, so long as the initializer has no side effects.
5376     if (!S.getLangOpts().CPlusPlus && Initializer &&
5377         isa<CompoundLiteralExpr>(Initializer->IgnoreParens()) &&
5378         Initializer->getType()->isArrayType()) {
5379       const ArrayType *SourceAT
5380         = Context.getAsArrayType(Initializer->getType());
5381       if (!hasCompatibleArrayTypes(S.Context, DestAT, SourceAT))
5382         SetFailed(FK_ArrayTypeMismatch);
5383       else if (Initializer->HasSideEffects(S.Context))
5384         SetFailed(FK_NonConstantArrayInit);
5385       else {
5386         AddArrayInitStep(DestType, /*IsGNUExtension*/true);
5387       }
5388     }
5389     // Note: as a GNU C++ extension, we allow list-initialization of a
5390     // class member of array type from a parenthesized initializer list.
5391     else if (S.getLangOpts().CPlusPlus &&
5392              Entity.getKind() == InitializedEntity::EK_Member &&
5393              Initializer && isa<InitListExpr>(Initializer)) {
5394       TryListInitialization(S, Entity, Kind, cast<InitListExpr>(Initializer),
5395                             *this, TreatUnavailableAsInvalid);
5396       AddParenthesizedArrayInitStep(DestType);
5397     } else if (DestAT->getElementType()->isCharType())
5398       SetFailed(FK_ArrayNeedsInitListOrStringLiteral);
5399     else if (IsWideCharCompatible(DestAT->getElementType(), Context))
5400       SetFailed(FK_ArrayNeedsInitListOrWideStringLiteral);
5401     else
5402       SetFailed(FK_ArrayNeedsInitList);
5403
5404     return;
5405   }
5406
5407   // Determine whether we should consider writeback conversions for
5408   // Objective-C ARC.
5409   bool allowObjCWritebackConversion = S.getLangOpts().ObjCAutoRefCount &&
5410          Entity.isParameterKind();
5411
5412   // We're at the end of the line for C: it's either a write-back conversion
5413   // or it's a C assignment. There's no need to check anything else.
5414   if (!S.getLangOpts().CPlusPlus) {
5415     // If allowed, check whether this is an Objective-C writeback conversion.
5416     if (allowObjCWritebackConversion &&
5417         tryObjCWritebackConversion(S, *this, Entity, Initializer)) {
5418       return;
5419     }
5420
5421     if (TryOCLSamplerInitialization(S, *this, DestType, Initializer))
5422       return;
5423
5424     if (TryOCLZeroEventInitialization(S, *this, DestType, Initializer))
5425       return;
5426
5427     if (TryOCLZeroQueueInitialization(S, *this, DestType, Initializer))
5428        return;
5429
5430     // Handle initialization in C
5431     AddCAssignmentStep(DestType);
5432     MaybeProduceObjCObject(S, *this, Entity);
5433     return;
5434   }
5435
5436   assert(S.getLangOpts().CPlusPlus);
5437
5438   //     - If the destination type is a (possibly cv-qualified) class type:
5439   if (DestType->isRecordType()) {
5440     //     - If the initialization is direct-initialization, or if it is
5441     //       copy-initialization where the cv-unqualified version of the
5442     //       source type is the same class as, or a derived class of, the
5443     //       class of the destination, constructors are considered. [...]
5444     if (Kind.getKind() == InitializationKind::IK_Direct ||
5445         (Kind.getKind() == InitializationKind::IK_Copy &&
5446          (Context.hasSameUnqualifiedType(SourceType, DestType) ||
5447           S.IsDerivedFrom(Initializer->getLocStart(), SourceType, DestType))))
5448       TryConstructorInitialization(S, Entity, Kind, Args,
5449                                    DestType, DestType, *this);
5450     //     - Otherwise (i.e., for the remaining copy-initialization cases),
5451     //       user-defined conversion sequences that can convert from the source
5452     //       type to the destination type or (when a conversion function is
5453     //       used) to a derived class thereof are enumerated as described in
5454     //       13.3.1.4, and the best one is chosen through overload resolution
5455     //       (13.3).
5456     else
5457       TryUserDefinedConversion(S, DestType, Kind, Initializer, *this,
5458                                TopLevelOfInitList);
5459     return;
5460   }
5461
5462   assert(Args.size() >= 1 && "Zero-argument case handled above");
5463
5464   // The remaining cases all need a source type.
5465   if (Args.size() > 1) {
5466     SetFailed(FK_TooManyInitsForScalar);
5467     return;
5468   } else if (isa<InitListExpr>(Args[0])) {
5469     SetFailed(FK_ParenthesizedListInitForScalar);
5470     return;
5471   }
5472
5473   //    - Otherwise, if the source type is a (possibly cv-qualified) class
5474   //      type, conversion functions are considered.
5475   if (!SourceType.isNull() && SourceType->isRecordType()) {
5476     // For a conversion to _Atomic(T) from either T or a class type derived
5477     // from T, initialize the T object then convert to _Atomic type.
5478     bool NeedAtomicConversion = false;
5479     if (const AtomicType *Atomic = DestType->getAs<AtomicType>()) {
5480       if (Context.hasSameUnqualifiedType(SourceType, Atomic->getValueType()) ||
5481           S.IsDerivedFrom(Initializer->getLocStart(), SourceType,
5482                           Atomic->getValueType())) {
5483         DestType = Atomic->getValueType();
5484         NeedAtomicConversion = true;
5485       }
5486     }
5487
5488     TryUserDefinedConversion(S, DestType, Kind, Initializer, *this,
5489                              TopLevelOfInitList);
5490     MaybeProduceObjCObject(S, *this, Entity);
5491     if (!Failed() && NeedAtomicConversion)
5492       AddAtomicConversionStep(Entity.getType());
5493     return;
5494   }
5495
5496   //    - Otherwise, the initial value of the object being initialized is the
5497   //      (possibly converted) value of the initializer expression. Standard
5498   //      conversions (Clause 4) will be used, if necessary, to convert the
5499   //      initializer expression to the cv-unqualified version of the
5500   //      destination type; no user-defined conversions are considered.
5501
5502   ImplicitConversionSequence ICS
5503     = S.TryImplicitConversion(Initializer, DestType,
5504                               /*SuppressUserConversions*/true,
5505                               /*AllowExplicitConversions*/ false,
5506                               /*InOverloadResolution*/ false,
5507                               /*CStyle=*/Kind.isCStyleOrFunctionalCast(),
5508                               allowObjCWritebackConversion);
5509
5510   if (ICS.isStandard() &&
5511       ICS.Standard.Second == ICK_Writeback_Conversion) {
5512     // Objective-C ARC writeback conversion.
5513
5514     // We should copy unless we're passing to an argument explicitly
5515     // marked 'out'.
5516     bool ShouldCopy = true;
5517     if (ParmVarDecl *Param = cast_or_null<ParmVarDecl>(Entity.getDecl()))
5518       ShouldCopy = (Param->getObjCDeclQualifier() != ParmVarDecl::OBJC_TQ_Out);
5519
5520     // If there was an lvalue adjustment, add it as a separate conversion.
5521     if (ICS.Standard.First == ICK_Array_To_Pointer ||
5522         ICS.Standard.First == ICK_Lvalue_To_Rvalue) {
5523       ImplicitConversionSequence LvalueICS;
5524       LvalueICS.setStandard();
5525       LvalueICS.Standard.setAsIdentityConversion();
5526       LvalueICS.Standard.setAllToTypes(ICS.Standard.getToType(0));
5527       LvalueICS.Standard.First = ICS.Standard.First;
5528       AddConversionSequenceStep(LvalueICS, ICS.Standard.getToType(0));
5529     }
5530
5531     AddPassByIndirectCopyRestoreStep(DestType, ShouldCopy);
5532   } else if (ICS.isBad()) {
5533     DeclAccessPair dap;
5534     if (isLibstdcxxPointerReturnFalseHack(S, Entity, Initializer)) {
5535       AddZeroInitializationStep(Entity.getType());
5536     } else if (Initializer->getType() == Context.OverloadTy &&
5537                !S.ResolveAddressOfOverloadedFunction(Initializer, DestType,
5538                                                      false, dap))
5539       SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
5540     else if (Initializer->getType()->isFunctionType() &&
5541              isExprAnUnaddressableFunction(S, Initializer))
5542       SetFailed(InitializationSequence::FK_AddressOfUnaddressableFunction);
5543     else
5544       SetFailed(InitializationSequence::FK_ConversionFailed);
5545   } else {
5546     AddConversionSequenceStep(ICS, DestType, TopLevelOfInitList);
5547
5548     MaybeProduceObjCObject(S, *this, Entity);
5549   }
5550 }
5551
5552 InitializationSequence::~InitializationSequence() {
5553   for (auto &S : Steps)
5554     S.Destroy();
5555 }
5556
5557 //===----------------------------------------------------------------------===//
5558 // Perform initialization
5559 //===----------------------------------------------------------------------===//
5560 static Sema::AssignmentAction
5561 getAssignmentAction(const InitializedEntity &Entity, bool Diagnose = false) {
5562   switch(Entity.getKind()) {
5563   case InitializedEntity::EK_Variable:
5564   case InitializedEntity::EK_New:
5565   case InitializedEntity::EK_Exception:
5566   case InitializedEntity::EK_Base:
5567   case InitializedEntity::EK_Delegating:
5568     return Sema::AA_Initializing;
5569
5570   case InitializedEntity::EK_Parameter:
5571     if (Entity.getDecl() &&
5572         isa<ObjCMethodDecl>(Entity.getDecl()->getDeclContext()))
5573       return Sema::AA_Sending;
5574
5575     return Sema::AA_Passing;
5576
5577   case InitializedEntity::EK_Parameter_CF_Audited:
5578     if (Entity.getDecl() &&
5579       isa<ObjCMethodDecl>(Entity.getDecl()->getDeclContext()))
5580       return Sema::AA_Sending;
5581
5582     return !Diagnose ? Sema::AA_Passing : Sema::AA_Passing_CFAudited;
5583
5584   case InitializedEntity::EK_Result:
5585     return Sema::AA_Returning;
5586
5587   case InitializedEntity::EK_Temporary:
5588   case InitializedEntity::EK_RelatedResult:
5589     // FIXME: Can we tell apart casting vs. converting?
5590     return Sema::AA_Casting;
5591
5592   case InitializedEntity::EK_Member:
5593   case InitializedEntity::EK_Binding:
5594   case InitializedEntity::EK_ArrayElement:
5595   case InitializedEntity::EK_VectorElement:
5596   case InitializedEntity::EK_ComplexElement:
5597   case InitializedEntity::EK_BlockElement:
5598   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5599   case InitializedEntity::EK_LambdaCapture:
5600   case InitializedEntity::EK_CompoundLiteralInit:
5601     return Sema::AA_Initializing;
5602   }
5603
5604   llvm_unreachable("Invalid EntityKind!");
5605 }
5606
5607 /// \brief Whether we should bind a created object as a temporary when
5608 /// initializing the given entity.
5609 static bool shouldBindAsTemporary(const InitializedEntity &Entity) {
5610   switch (Entity.getKind()) {
5611   case InitializedEntity::EK_ArrayElement:
5612   case InitializedEntity::EK_Member:
5613   case InitializedEntity::EK_Result:
5614   case InitializedEntity::EK_New:
5615   case InitializedEntity::EK_Variable:
5616   case InitializedEntity::EK_Base:
5617   case InitializedEntity::EK_Delegating:
5618   case InitializedEntity::EK_VectorElement:
5619   case InitializedEntity::EK_ComplexElement:
5620   case InitializedEntity::EK_Exception:
5621   case InitializedEntity::EK_BlockElement:
5622   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5623   case InitializedEntity::EK_LambdaCapture:
5624   case InitializedEntity::EK_CompoundLiteralInit:
5625     return false;
5626
5627   case InitializedEntity::EK_Parameter:
5628   case InitializedEntity::EK_Parameter_CF_Audited:
5629   case InitializedEntity::EK_Temporary:
5630   case InitializedEntity::EK_RelatedResult:
5631   case InitializedEntity::EK_Binding:
5632     return true;
5633   }
5634
5635   llvm_unreachable("missed an InitializedEntity kind?");
5636 }
5637
5638 /// \brief Whether the given entity, when initialized with an object
5639 /// created for that initialization, requires destruction.
5640 static bool shouldDestroyEntity(const InitializedEntity &Entity) {
5641   switch (Entity.getKind()) {
5642     case InitializedEntity::EK_Result:
5643     case InitializedEntity::EK_New:
5644     case InitializedEntity::EK_Base:
5645     case InitializedEntity::EK_Delegating:
5646     case InitializedEntity::EK_VectorElement:
5647     case InitializedEntity::EK_ComplexElement:
5648     case InitializedEntity::EK_BlockElement:
5649     case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5650     case InitializedEntity::EK_LambdaCapture:
5651       return false;
5652
5653     case InitializedEntity::EK_Member:
5654     case InitializedEntity::EK_Binding:
5655     case InitializedEntity::EK_Variable:
5656     case InitializedEntity::EK_Parameter:
5657     case InitializedEntity::EK_Parameter_CF_Audited:
5658     case InitializedEntity::EK_Temporary:
5659     case InitializedEntity::EK_ArrayElement:
5660     case InitializedEntity::EK_Exception:
5661     case InitializedEntity::EK_CompoundLiteralInit:
5662     case InitializedEntity::EK_RelatedResult:
5663       return true;
5664   }
5665
5666   llvm_unreachable("missed an InitializedEntity kind?");
5667 }
5668
5669 /// \brief Get the location at which initialization diagnostics should appear.
5670 static SourceLocation getInitializationLoc(const InitializedEntity &Entity,
5671                                            Expr *Initializer) {
5672   switch (Entity.getKind()) {
5673   case InitializedEntity::EK_Result:
5674     return Entity.getReturnLoc();
5675
5676   case InitializedEntity::EK_Exception:
5677     return Entity.getThrowLoc();
5678
5679   case InitializedEntity::EK_Variable:
5680   case InitializedEntity::EK_Binding:
5681     return Entity.getDecl()->getLocation();
5682
5683   case InitializedEntity::EK_LambdaCapture:
5684     return Entity.getCaptureLoc();
5685
5686   case InitializedEntity::EK_ArrayElement:
5687   case InitializedEntity::EK_Member:
5688   case InitializedEntity::EK_Parameter:
5689   case InitializedEntity::EK_Parameter_CF_Audited:
5690   case InitializedEntity::EK_Temporary:
5691   case InitializedEntity::EK_New:
5692   case InitializedEntity::EK_Base:
5693   case InitializedEntity::EK_Delegating:
5694   case InitializedEntity::EK_VectorElement:
5695   case InitializedEntity::EK_ComplexElement:
5696   case InitializedEntity::EK_BlockElement:
5697   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
5698   case InitializedEntity::EK_CompoundLiteralInit:
5699   case InitializedEntity::EK_RelatedResult:
5700     return Initializer->getLocStart();
5701   }
5702   llvm_unreachable("missed an InitializedEntity kind?");
5703 }
5704
5705 /// \brief Make a (potentially elidable) temporary copy of the object
5706 /// provided by the given initializer by calling the appropriate copy
5707 /// constructor.
5708 ///
5709 /// \param S The Sema object used for type-checking.
5710 ///
5711 /// \param T The type of the temporary object, which must either be
5712 /// the type of the initializer expression or a superclass thereof.
5713 ///
5714 /// \param Entity The entity being initialized.
5715 ///
5716 /// \param CurInit The initializer expression.
5717 ///
5718 /// \param IsExtraneousCopy Whether this is an "extraneous" copy that
5719 /// is permitted in C++03 (but not C++0x) when binding a reference to
5720 /// an rvalue.
5721 ///
5722 /// \returns An expression that copies the initializer expression into
5723 /// a temporary object, or an error expression if a copy could not be
5724 /// created.
5725 static ExprResult CopyObject(Sema &S,
5726                              QualType T,
5727                              const InitializedEntity &Entity,
5728                              ExprResult CurInit,
5729                              bool IsExtraneousCopy) {
5730   if (CurInit.isInvalid())
5731     return CurInit;
5732   // Determine which class type we're copying to.
5733   Expr *CurInitExpr = (Expr *)CurInit.get();
5734   CXXRecordDecl *Class = nullptr;
5735   if (const RecordType *Record = T->getAs<RecordType>())
5736     Class = cast<CXXRecordDecl>(Record->getDecl());
5737   if (!Class)
5738     return CurInit;
5739
5740   SourceLocation Loc = getInitializationLoc(Entity, CurInit.get());
5741
5742   // Make sure that the type we are copying is complete.
5743   if (S.RequireCompleteType(Loc, T, diag::err_temp_copy_incomplete))
5744     return CurInit;
5745
5746   // Perform overload resolution using the class's constructors. Per
5747   // C++11 [dcl.init]p16, second bullet for class types, this initialization
5748   // is direct-initialization.
5749   OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
5750   DeclContext::lookup_result Ctors = S.LookupConstructors(Class);
5751
5752   OverloadCandidateSet::iterator Best;
5753   switch (ResolveConstructorOverload(
5754       S, Loc, CurInitExpr, CandidateSet, T, Ctors, Best,
5755       /*CopyInitializing=*/false, /*AllowExplicit=*/true,
5756       /*OnlyListConstructors=*/false, /*IsListInit=*/false,
5757       /*SecondStepOfCopyInit=*/true)) {
5758   case OR_Success:
5759     break;
5760
5761   case OR_No_Viable_Function:
5762     S.Diag(Loc, IsExtraneousCopy && !S.isSFINAEContext()
5763            ? diag::ext_rvalue_to_reference_temp_copy_no_viable
5764            : diag::err_temp_copy_no_viable)
5765       << (int)Entity.getKind() << CurInitExpr->getType()
5766       << CurInitExpr->getSourceRange();
5767     CandidateSet.NoteCandidates(S, OCD_AllCandidates, CurInitExpr);
5768     if (!IsExtraneousCopy || S.isSFINAEContext())
5769       return ExprError();
5770     return CurInit;
5771
5772   case OR_Ambiguous:
5773     S.Diag(Loc, diag::err_temp_copy_ambiguous)
5774       << (int)Entity.getKind() << CurInitExpr->getType()
5775       << CurInitExpr->getSourceRange();
5776     CandidateSet.NoteCandidates(S, OCD_ViableCandidates, CurInitExpr);
5777     return ExprError();
5778
5779   case OR_Deleted:
5780     S.Diag(Loc, diag::err_temp_copy_deleted)
5781       << (int)Entity.getKind() << CurInitExpr->getType()
5782       << CurInitExpr->getSourceRange();
5783     S.NoteDeletedFunction(Best->Function);
5784     return ExprError();
5785   }
5786
5787   bool HadMultipleCandidates = CandidateSet.size() > 1;
5788
5789   CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(Best->Function);
5790   SmallVector<Expr*, 8> ConstructorArgs;
5791   CurInit.get(); // Ownership transferred into MultiExprArg, below.
5792
5793   S.CheckConstructorAccess(Loc, Constructor, Best->FoundDecl, Entity,
5794                            IsExtraneousCopy);
5795
5796   if (IsExtraneousCopy) {
5797     // If this is a totally extraneous copy for C++03 reference
5798     // binding purposes, just return the original initialization
5799     // expression. We don't generate an (elided) copy operation here
5800     // because doing so would require us to pass down a flag to avoid
5801     // infinite recursion, where each step adds another extraneous,
5802     // elidable copy.
5803
5804     // Instantiate the default arguments of any extra parameters in
5805     // the selected copy constructor, as if we were going to create a
5806     // proper call to the copy constructor.
5807     for (unsigned I = 1, N = Constructor->getNumParams(); I != N; ++I) {
5808       ParmVarDecl *Parm = Constructor->getParamDecl(I);
5809       if (S.RequireCompleteType(Loc, Parm->getType(),
5810                                 diag::err_call_incomplete_argument))
5811         break;
5812
5813       // Build the default argument expression; we don't actually care
5814       // if this succeeds or not, because this routine will complain
5815       // if there was a problem.
5816       S.BuildCXXDefaultArgExpr(Loc, Constructor, Parm);
5817     }
5818
5819     return CurInitExpr;
5820   }
5821
5822   // Determine the arguments required to actually perform the
5823   // constructor call (we might have derived-to-base conversions, or
5824   // the copy constructor may have default arguments).
5825   if (S.CompleteConstructorCall(Constructor, CurInitExpr, Loc, ConstructorArgs))
5826     return ExprError();
5827
5828   // C++0x [class.copy]p32:
5829   //   When certain criteria are met, an implementation is allowed to
5830   //   omit the copy/move construction of a class object, even if the
5831   //   copy/move constructor and/or destructor for the object have
5832   //   side effects. [...]
5833   //     - when a temporary class object that has not been bound to a
5834   //       reference (12.2) would be copied/moved to a class object
5835   //       with the same cv-unqualified type, the copy/move operation
5836   //       can be omitted by constructing the temporary object
5837   //       directly into the target of the omitted copy/move
5838   //
5839   // Note that the other three bullets are handled elsewhere. Copy
5840   // elision for return statements and throw expressions are handled as part
5841   // of constructor initialization, while copy elision for exception handlers
5842   // is handled by the run-time.
5843   //
5844   // FIXME: If the function parameter is not the same type as the temporary, we
5845   // should still be able to elide the copy, but we don't have a way to
5846   // represent in the AST how much should be elided in this case.
5847   bool Elidable =
5848       CurInitExpr->isTemporaryObject(S.Context, Class) &&
5849       S.Context.hasSameUnqualifiedType(
5850           Best->Function->getParamDecl(0)->getType().getNonReferenceType(),
5851           CurInitExpr->getType());
5852
5853   // Actually perform the constructor call.
5854   CurInit = S.BuildCXXConstructExpr(Loc, T, Best->FoundDecl, Constructor,
5855                                     Elidable,
5856                                     ConstructorArgs,
5857                                     HadMultipleCandidates,
5858                                     /*ListInit*/ false,
5859                                     /*StdInitListInit*/ false,
5860                                     /*ZeroInit*/ false,
5861                                     CXXConstructExpr::CK_Complete,
5862                                     SourceRange());
5863
5864   // If we're supposed to bind temporaries, do so.
5865   if (!CurInit.isInvalid() && shouldBindAsTemporary(Entity))
5866     CurInit = S.MaybeBindToTemporary(CurInit.getAs<Expr>());
5867   return CurInit;
5868 }
5869
5870 /// \brief Check whether elidable copy construction for binding a reference to
5871 /// a temporary would have succeeded if we were building in C++98 mode, for
5872 /// -Wc++98-compat.
5873 static void CheckCXX98CompatAccessibleCopy(Sema &S,
5874                                            const InitializedEntity &Entity,
5875                                            Expr *CurInitExpr) {
5876   assert(S.getLangOpts().CPlusPlus11);
5877
5878   const RecordType *Record = CurInitExpr->getType()->getAs<RecordType>();
5879   if (!Record)
5880     return;
5881
5882   SourceLocation Loc = getInitializationLoc(Entity, CurInitExpr);
5883   if (S.Diags.isIgnored(diag::warn_cxx98_compat_temp_copy, Loc))
5884     return;
5885
5886   // Find constructors which would have been considered.
5887   OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
5888   DeclContext::lookup_result Ctors =
5889       S.LookupConstructors(cast<CXXRecordDecl>(Record->getDecl()));
5890
5891   // Perform overload resolution.
5892   OverloadCandidateSet::iterator Best;
5893   OverloadingResult OR = ResolveConstructorOverload(
5894       S, Loc, CurInitExpr, CandidateSet, CurInitExpr->getType(), Ctors, Best,
5895       /*CopyInitializing=*/false, /*AllowExplicit=*/true,
5896       /*OnlyListConstructors=*/false, /*IsListInit=*/false,
5897       /*SecondStepOfCopyInit=*/true);
5898
5899   PartialDiagnostic Diag = S.PDiag(diag::warn_cxx98_compat_temp_copy)
5900     << OR << (int)Entity.getKind() << CurInitExpr->getType()
5901     << CurInitExpr->getSourceRange();
5902
5903   switch (OR) {
5904   case OR_Success:
5905     S.CheckConstructorAccess(Loc, cast<CXXConstructorDecl>(Best->Function),
5906                              Best->FoundDecl, Entity, Diag);
5907     // FIXME: Check default arguments as far as that's possible.
5908     break;
5909
5910   case OR_No_Viable_Function:
5911     S.Diag(Loc, Diag);
5912     CandidateSet.NoteCandidates(S, OCD_AllCandidates, CurInitExpr);
5913     break;
5914
5915   case OR_Ambiguous:
5916     S.Diag(Loc, Diag);
5917     CandidateSet.NoteCandidates(S, OCD_ViableCandidates, CurInitExpr);
5918     break;
5919
5920   case OR_Deleted:
5921     S.Diag(Loc, Diag);
5922     S.NoteDeletedFunction(Best->Function);
5923     break;
5924   }
5925 }
5926
5927 void InitializationSequence::PrintInitLocationNote(Sema &S,
5928                                               const InitializedEntity &Entity) {
5929   if (Entity.isParameterKind() && Entity.getDecl()) {
5930     if (Entity.getDecl()->getLocation().isInvalid())
5931       return;
5932
5933     if (Entity.getDecl()->getDeclName())
5934       S.Diag(Entity.getDecl()->getLocation(), diag::note_parameter_named_here)
5935         << Entity.getDecl()->getDeclName();
5936     else
5937       S.Diag(Entity.getDecl()->getLocation(), diag::note_parameter_here);
5938   }
5939   else if (Entity.getKind() == InitializedEntity::EK_RelatedResult &&
5940            Entity.getMethodDecl())
5941     S.Diag(Entity.getMethodDecl()->getLocation(),
5942            diag::note_method_return_type_change)
5943       << Entity.getMethodDecl()->getDeclName();
5944 }
5945
5946 /// Returns true if the parameters describe a constructor initialization of
5947 /// an explicit temporary object, e.g. "Point(x, y)".
5948 static bool isExplicitTemporary(const InitializedEntity &Entity,
5949                                 const InitializationKind &Kind,
5950                                 unsigned NumArgs) {
5951   switch (Entity.getKind()) {
5952   case InitializedEntity::EK_Temporary:
5953   case InitializedEntity::EK_CompoundLiteralInit:
5954   case InitializedEntity::EK_RelatedResult:
5955     break;
5956   default:
5957     return false;
5958   }
5959
5960   switch (Kind.getKind()) {
5961   case InitializationKind::IK_DirectList:
5962     return true;
5963   // FIXME: Hack to work around cast weirdness.
5964   case InitializationKind::IK_Direct:
5965   case InitializationKind::IK_Value:
5966     return NumArgs != 1;
5967   default:
5968     return false;
5969   }
5970 }
5971
5972 static ExprResult
5973 PerformConstructorInitialization(Sema &S,
5974                                  const InitializedEntity &Entity,
5975                                  const InitializationKind &Kind,
5976                                  MultiExprArg Args,
5977                                  const InitializationSequence::Step& Step,
5978                                  bool &ConstructorInitRequiresZeroInit,
5979                                  bool IsListInitialization,
5980                                  bool IsStdInitListInitialization,
5981                                  SourceLocation LBraceLoc,
5982                                  SourceLocation RBraceLoc) {
5983   unsigned NumArgs = Args.size();
5984   CXXConstructorDecl *Constructor
5985     = cast<CXXConstructorDecl>(Step.Function.Function);
5986   bool HadMultipleCandidates = Step.Function.HadMultipleCandidates;
5987
5988   // Build a call to the selected constructor.
5989   SmallVector<Expr*, 8> ConstructorArgs;
5990   SourceLocation Loc = (Kind.isCopyInit() && Kind.getEqualLoc().isValid())
5991                          ? Kind.getEqualLoc()
5992                          : Kind.getLocation();
5993
5994   if (Kind.getKind() == InitializationKind::IK_Default) {
5995     // Force even a trivial, implicit default constructor to be
5996     // semantically checked. We do this explicitly because we don't build
5997     // the definition for completely trivial constructors.
5998     assert(Constructor->getParent() && "No parent class for constructor.");
5999     if (Constructor->isDefaulted() && Constructor->isDefaultConstructor() &&
6000         Constructor->isTrivial() && !Constructor->isUsed(false))
6001       S.DefineImplicitDefaultConstructor(Loc, Constructor);
6002   }
6003
6004   ExprResult CurInit((Expr *)nullptr);
6005
6006   // C++ [over.match.copy]p1:
6007   //   - When initializing a temporary to be bound to the first parameter
6008   //     of a constructor that takes a reference to possibly cv-qualified
6009   //     T as its first argument, called with a single argument in the
6010   //     context of direct-initialization, explicit conversion functions
6011   //     are also considered.
6012   bool AllowExplicitConv =
6013       Kind.AllowExplicit() && !Kind.isCopyInit() && Args.size() == 1 &&
6014       hasCopyOrMoveCtorParam(S.Context,
6015                              getConstructorInfo(Step.Function.FoundDecl));
6016
6017   // Determine the arguments required to actually perform the constructor
6018   // call.
6019   if (S.CompleteConstructorCall(Constructor, Args,
6020                                 Loc, ConstructorArgs,
6021                                 AllowExplicitConv,
6022                                 IsListInitialization))
6023     return ExprError();
6024
6025
6026   if (isExplicitTemporary(Entity, Kind, NumArgs)) {
6027     // An explicitly-constructed temporary, e.g., X(1, 2).
6028     if (S.DiagnoseUseOfDecl(Constructor, Loc))
6029       return ExprError();
6030
6031     TypeSourceInfo *TSInfo = Entity.getTypeSourceInfo();
6032     if (!TSInfo)
6033       TSInfo = S.Context.getTrivialTypeSourceInfo(Entity.getType(), Loc);
6034     SourceRange ParenOrBraceRange =
6035       (Kind.getKind() == InitializationKind::IK_DirectList)
6036       ? SourceRange(LBraceLoc, RBraceLoc)
6037       : Kind.getParenRange();
6038
6039     if (auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(
6040             Step.Function.FoundDecl.getDecl())) {
6041       Constructor = S.findInheritingConstructor(Loc, Constructor, Shadow);
6042       if (S.DiagnoseUseOfDecl(Constructor, Loc))
6043         return ExprError();
6044     }
6045     S.MarkFunctionReferenced(Loc, Constructor);
6046
6047     CurInit = new (S.Context) CXXTemporaryObjectExpr(
6048         S.Context, Constructor,
6049         Entity.getType().getNonLValueExprType(S.Context), TSInfo,
6050         ConstructorArgs, ParenOrBraceRange, HadMultipleCandidates,
6051         IsListInitialization, IsStdInitListInitialization,
6052         ConstructorInitRequiresZeroInit);
6053   } else {
6054     CXXConstructExpr::ConstructionKind ConstructKind =
6055       CXXConstructExpr::CK_Complete;
6056
6057     if (Entity.getKind() == InitializedEntity::EK_Base) {
6058       ConstructKind = Entity.getBaseSpecifier()->isVirtual() ?
6059         CXXConstructExpr::CK_VirtualBase :
6060         CXXConstructExpr::CK_NonVirtualBase;
6061     } else if (Entity.getKind() == InitializedEntity::EK_Delegating) {
6062       ConstructKind = CXXConstructExpr::CK_Delegating;
6063     }
6064
6065     // Only get the parenthesis or brace range if it is a list initialization or
6066     // direct construction.
6067     SourceRange ParenOrBraceRange;
6068     if (IsListInitialization)
6069       ParenOrBraceRange = SourceRange(LBraceLoc, RBraceLoc);
6070     else if (Kind.getKind() == InitializationKind::IK_Direct)
6071       ParenOrBraceRange = Kind.getParenRange();
6072
6073     // If the entity allows NRVO, mark the construction as elidable
6074     // unconditionally.
6075     if (Entity.allowsNRVO())
6076       CurInit = S.BuildCXXConstructExpr(Loc, Step.Type,
6077                                         Step.Function.FoundDecl,
6078                                         Constructor, /*Elidable=*/true,
6079                                         ConstructorArgs,
6080                                         HadMultipleCandidates,
6081                                         IsListInitialization,
6082                                         IsStdInitListInitialization,
6083                                         ConstructorInitRequiresZeroInit,
6084                                         ConstructKind,
6085                                         ParenOrBraceRange);
6086     else
6087       CurInit = S.BuildCXXConstructExpr(Loc, Step.Type,
6088                                         Step.Function.FoundDecl,
6089                                         Constructor,
6090                                         ConstructorArgs,
6091                                         HadMultipleCandidates,
6092                                         IsListInitialization,
6093                                         IsStdInitListInitialization,
6094                                         ConstructorInitRequiresZeroInit,
6095                                         ConstructKind,
6096                                         ParenOrBraceRange);
6097   }
6098   if (CurInit.isInvalid())
6099     return ExprError();
6100
6101   // Only check access if all of that succeeded.
6102   S.CheckConstructorAccess(Loc, Constructor, Step.Function.FoundDecl, Entity);
6103   if (S.DiagnoseUseOfDecl(Step.Function.FoundDecl, Loc))
6104     return ExprError();
6105
6106   if (shouldBindAsTemporary(Entity))
6107     CurInit = S.MaybeBindToTemporary(CurInit.get());
6108
6109   return CurInit;
6110 }
6111
6112 /// Determine whether the specified InitializedEntity definitely has a lifetime
6113 /// longer than the current full-expression. Conservatively returns false if
6114 /// it's unclear.
6115 static bool
6116 InitializedEntityOutlivesFullExpression(const InitializedEntity &Entity) {
6117   const InitializedEntity *Top = &Entity;
6118   while (Top->getParent())
6119     Top = Top->getParent();
6120
6121   switch (Top->getKind()) {
6122   case InitializedEntity::EK_Variable:
6123   case InitializedEntity::EK_Result:
6124   case InitializedEntity::EK_Exception:
6125   case InitializedEntity::EK_Member:
6126   case InitializedEntity::EK_Binding:
6127   case InitializedEntity::EK_New:
6128   case InitializedEntity::EK_Base:
6129   case InitializedEntity::EK_Delegating:
6130     return true;
6131
6132   case InitializedEntity::EK_ArrayElement:
6133   case InitializedEntity::EK_VectorElement:
6134   case InitializedEntity::EK_BlockElement:
6135   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
6136   case InitializedEntity::EK_ComplexElement:
6137     // Could not determine what the full initialization is. Assume it might not
6138     // outlive the full-expression.
6139     return false;
6140
6141   case InitializedEntity::EK_Parameter:
6142   case InitializedEntity::EK_Parameter_CF_Audited:
6143   case InitializedEntity::EK_Temporary:
6144   case InitializedEntity::EK_LambdaCapture:
6145   case InitializedEntity::EK_CompoundLiteralInit:
6146   case InitializedEntity::EK_RelatedResult:
6147     // The entity being initialized might not outlive the full-expression.
6148     return false;
6149   }
6150
6151   llvm_unreachable("unknown entity kind");
6152 }
6153
6154 /// Determine the declaration which an initialized entity ultimately refers to,
6155 /// for the purpose of lifetime-extending a temporary bound to a reference in
6156 /// the initialization of \p Entity.
6157 static const InitializedEntity *getEntityForTemporaryLifetimeExtension(
6158     const InitializedEntity *Entity,
6159     const InitializedEntity *FallbackDecl = nullptr) {
6160   // C++11 [class.temporary]p5:
6161   switch (Entity->getKind()) {
6162   case InitializedEntity::EK_Variable:
6163     //   The temporary [...] persists for the lifetime of the reference
6164     return Entity;
6165
6166   case InitializedEntity::EK_Member:
6167     // For subobjects, we look at the complete object.
6168     if (Entity->getParent())
6169       return getEntityForTemporaryLifetimeExtension(Entity->getParent(),
6170                                                     Entity);
6171
6172     //   except:
6173     //   -- A temporary bound to a reference member in a constructor's
6174     //      ctor-initializer persists until the constructor exits.
6175     return Entity;
6176
6177   case InitializedEntity::EK_Binding:
6178     // Per [dcl.decomp]p3, the binding is treated as a variable of reference
6179     // type.
6180     return Entity;
6181
6182   case InitializedEntity::EK_Parameter:
6183   case InitializedEntity::EK_Parameter_CF_Audited:
6184     //   -- A temporary bound to a reference parameter in a function call
6185     //      persists until the completion of the full-expression containing
6186     //      the call.
6187   case InitializedEntity::EK_Result:
6188     //   -- The lifetime of a temporary bound to the returned value in a
6189     //      function return statement is not extended; the temporary is
6190     //      destroyed at the end of the full-expression in the return statement.
6191   case InitializedEntity::EK_New:
6192     //   -- A temporary bound to a reference in a new-initializer persists
6193     //      until the completion of the full-expression containing the
6194     //      new-initializer.
6195     return nullptr;
6196
6197   case InitializedEntity::EK_Temporary:
6198   case InitializedEntity::EK_CompoundLiteralInit:
6199   case InitializedEntity::EK_RelatedResult:
6200     // We don't yet know the storage duration of the surrounding temporary.
6201     // Assume it's got full-expression duration for now, it will patch up our
6202     // storage duration if that's not correct.
6203     return nullptr;
6204
6205   case InitializedEntity::EK_ArrayElement:
6206     // For subobjects, we look at the complete object.
6207     return getEntityForTemporaryLifetimeExtension(Entity->getParent(),
6208                                                   FallbackDecl);
6209
6210   case InitializedEntity::EK_Base:
6211     // For subobjects, we look at the complete object.
6212     if (Entity->getParent())
6213       return getEntityForTemporaryLifetimeExtension(Entity->getParent(),
6214                                                     Entity);
6215     LLVM_FALLTHROUGH;
6216   case InitializedEntity::EK_Delegating:
6217     // We can reach this case for aggregate initialization in a constructor:
6218     //   struct A { int &&r; };
6219     //   struct B : A { B() : A{0} {} };
6220     // In this case, use the innermost field decl as the context.
6221     return FallbackDecl;
6222
6223   case InitializedEntity::EK_BlockElement:
6224   case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
6225   case InitializedEntity::EK_LambdaCapture:
6226   case InitializedEntity::EK_Exception:
6227   case InitializedEntity::EK_VectorElement:
6228   case InitializedEntity::EK_ComplexElement:
6229     return nullptr;
6230   }
6231   llvm_unreachable("unknown entity kind");
6232 }
6233
6234 static void performLifetimeExtension(Expr *Init,
6235                                      const InitializedEntity *ExtendingEntity);
6236
6237 /// Update a glvalue expression that is used as the initializer of a reference
6238 /// to note that its lifetime is extended.
6239 /// \return \c true if any temporary had its lifetime extended.
6240 static bool
6241 performReferenceExtension(Expr *Init,
6242                           const InitializedEntity *ExtendingEntity) {
6243   // Walk past any constructs which we can lifetime-extend across.
6244   Expr *Old;
6245   do {
6246     Old = Init;
6247
6248     if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
6249       if (ILE->getNumInits() == 1 && ILE->isGLValue()) {
6250         // This is just redundant braces around an initializer. Step over it.
6251         Init = ILE->getInit(0);
6252       }
6253     }
6254
6255     // Step over any subobject adjustments; we may have a materialized
6256     // temporary inside them.
6257     Init = const_cast<Expr *>(Init->skipRValueSubobjectAdjustments());
6258
6259     // Per current approach for DR1376, look through casts to reference type
6260     // when performing lifetime extension.
6261     if (CastExpr *CE = dyn_cast<CastExpr>(Init))
6262       if (CE->getSubExpr()->isGLValue())
6263         Init = CE->getSubExpr();
6264
6265     // Per the current approach for DR1299, look through array element access
6266     // when performing lifetime extension.
6267     if (auto *ASE = dyn_cast<ArraySubscriptExpr>(Init))
6268       Init = ASE->getBase();
6269   } while (Init != Old);
6270
6271   if (MaterializeTemporaryExpr *ME = dyn_cast<MaterializeTemporaryExpr>(Init)) {
6272     // Update the storage duration of the materialized temporary.
6273     // FIXME: Rebuild the expression instead of mutating it.
6274     ME->setExtendingDecl(ExtendingEntity->getDecl(),
6275                          ExtendingEntity->allocateManglingNumber());
6276     performLifetimeExtension(ME->GetTemporaryExpr(), ExtendingEntity);
6277     return true;
6278   }
6279
6280   return false;
6281 }
6282
6283 /// Update a prvalue expression that is going to be materialized as a
6284 /// lifetime-extended temporary.
6285 static void performLifetimeExtension(Expr *Init,
6286                                      const InitializedEntity *ExtendingEntity) {
6287   // Dig out the expression which constructs the extended temporary.
6288   Init = const_cast<Expr *>(Init->skipRValueSubobjectAdjustments());
6289
6290   if (CXXBindTemporaryExpr *BTE = dyn_cast<CXXBindTemporaryExpr>(Init))
6291     Init = BTE->getSubExpr();
6292
6293   if (CXXStdInitializerListExpr *ILE =
6294           dyn_cast<CXXStdInitializerListExpr>(Init)) {
6295     performReferenceExtension(ILE->getSubExpr(), ExtendingEntity);
6296     return;
6297   }
6298
6299   if (InitListExpr *ILE = dyn_cast<InitListExpr>(Init)) {
6300     if (ILE->getType()->isArrayType()) {
6301       for (unsigned I = 0, N = ILE->getNumInits(); I != N; ++I)
6302         performLifetimeExtension(ILE->getInit(I), ExtendingEntity);
6303       return;
6304     }
6305
6306     if (CXXRecordDecl *RD = ILE->getType()->getAsCXXRecordDecl()) {
6307       assert(RD->isAggregate() && "aggregate init on non-aggregate");
6308
6309       // If we lifetime-extend a braced initializer which is initializing an
6310       // aggregate, and that aggregate contains reference members which are
6311       // bound to temporaries, those temporaries are also lifetime-extended.
6312       if (RD->isUnion() && ILE->getInitializedFieldInUnion() &&
6313           ILE->getInitializedFieldInUnion()->getType()->isReferenceType())
6314         performReferenceExtension(ILE->getInit(0), ExtendingEntity);
6315       else {
6316         unsigned Index = 0;
6317         for (const auto *I : RD->fields()) {
6318           if (Index >= ILE->getNumInits())
6319             break;
6320           if (I->isUnnamedBitfield())
6321             continue;
6322           Expr *SubInit = ILE->getInit(Index);
6323           if (I->getType()->isReferenceType())
6324             performReferenceExtension(SubInit, ExtendingEntity);
6325           else if (isa<InitListExpr>(SubInit) ||
6326                    isa<CXXStdInitializerListExpr>(SubInit))
6327             // This may be either aggregate-initialization of a member or
6328             // initialization of a std::initializer_list object. Either way,
6329             // we should recursively lifetime-extend that initializer.
6330             performLifetimeExtension(SubInit, ExtendingEntity);
6331           ++Index;
6332         }
6333       }
6334     }
6335   }
6336 }
6337
6338 static void warnOnLifetimeExtension(Sema &S, const InitializedEntity &Entity,
6339                                     const Expr *Init, bool IsInitializerList,
6340                                     const ValueDecl *ExtendingDecl) {
6341   // Warn if a field lifetime-extends a temporary.
6342   if (isa<FieldDecl>(ExtendingDecl)) {
6343     if (IsInitializerList) {
6344       S.Diag(Init->getExprLoc(), diag::warn_dangling_std_initializer_list)
6345         << /*at end of constructor*/true;
6346       return;
6347     }
6348
6349     bool IsSubobjectMember = false;
6350     for (const InitializedEntity *Ent = Entity.getParent(); Ent;
6351          Ent = Ent->getParent()) {
6352       if (Ent->getKind() != InitializedEntity::EK_Base) {
6353         IsSubobjectMember = true;
6354         break;
6355       }
6356     }
6357     S.Diag(Init->getExprLoc(),
6358            diag::warn_bind_ref_member_to_temporary)
6359       << ExtendingDecl << Init->getSourceRange()
6360       << IsSubobjectMember << IsInitializerList;
6361     if (IsSubobjectMember)
6362       S.Diag(ExtendingDecl->getLocation(),
6363              diag::note_ref_subobject_of_member_declared_here);
6364     else
6365       S.Diag(ExtendingDecl->getLocation(),
6366              diag::note_ref_or_ptr_member_declared_here)
6367         << /*is pointer*/false;
6368   }
6369 }
6370
6371 static void DiagnoseNarrowingInInitList(Sema &S,
6372                                         const ImplicitConversionSequence &ICS,
6373                                         QualType PreNarrowingType,
6374                                         QualType EntityType,
6375                                         const Expr *PostInit);
6376
6377 /// Provide warnings when std::move is used on construction.
6378 static void CheckMoveOnConstruction(Sema &S, const Expr *InitExpr,
6379                                     bool IsReturnStmt) {
6380   if (!InitExpr)
6381     return;
6382
6383   if (S.inTemplateInstantiation())
6384     return;
6385
6386   QualType DestType = InitExpr->getType();
6387   if (!DestType->isRecordType())
6388     return;
6389
6390   unsigned DiagID = 0;
6391   if (IsReturnStmt) {
6392     const CXXConstructExpr *CCE =
6393         dyn_cast<CXXConstructExpr>(InitExpr->IgnoreParens());
6394     if (!CCE || CCE->getNumArgs() != 1)
6395       return;
6396
6397     if (!CCE->getConstructor()->isCopyOrMoveConstructor())
6398       return;
6399
6400     InitExpr = CCE->getArg(0)->IgnoreImpCasts();
6401   }
6402
6403   // Find the std::move call and get the argument.
6404   const CallExpr *CE = dyn_cast<CallExpr>(InitExpr->IgnoreParens());
6405   if (!CE || CE->getNumArgs() != 1)
6406     return;
6407
6408   const FunctionDecl *MoveFunction = CE->getDirectCallee();
6409   if (!MoveFunction || !MoveFunction->isInStdNamespace() ||
6410       !MoveFunction->getIdentifier() ||
6411       !MoveFunction->getIdentifier()->isStr("move"))
6412     return;
6413
6414   const Expr *Arg = CE->getArg(0)->IgnoreImplicit();
6415
6416   if (IsReturnStmt) {
6417     const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg->IgnoreParenImpCasts());
6418     if (!DRE || DRE->refersToEnclosingVariableOrCapture())
6419       return;
6420
6421     const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl());
6422     if (!VD || !VD->hasLocalStorage())
6423       return;
6424
6425     // __block variables are not moved implicitly.
6426     if (VD->hasAttr<BlocksAttr>())
6427       return;
6428
6429     QualType SourceType = VD->getType();
6430     if (!SourceType->isRecordType())
6431       return;
6432
6433     if (!S.Context.hasSameUnqualifiedType(DestType, SourceType)) {
6434       return;
6435     }
6436
6437     // If we're returning a function parameter, copy elision
6438     // is not possible.
6439     if (isa<ParmVarDecl>(VD))
6440       DiagID = diag::warn_redundant_move_on_return;
6441     else
6442       DiagID = diag::warn_pessimizing_move_on_return;
6443   } else {
6444     DiagID = diag::warn_pessimizing_move_on_initialization;
6445     const Expr *ArgStripped = Arg->IgnoreImplicit()->IgnoreParens();
6446     if (!ArgStripped->isRValue() || !ArgStripped->getType()->isRecordType())
6447       return;
6448   }
6449
6450   S.Diag(CE->getLocStart(), DiagID);
6451
6452   // Get all the locations for a fix-it.  Don't emit the fix-it if any location
6453   // is within a macro.
6454   SourceLocation CallBegin = CE->getCallee()->getLocStart();
6455   if (CallBegin.isMacroID())
6456     return;
6457   SourceLocation RParen = CE->getRParenLoc();
6458   if (RParen.isMacroID())
6459     return;
6460   SourceLocation LParen;
6461   SourceLocation ArgLoc = Arg->getLocStart();
6462
6463   // Special testing for the argument location.  Since the fix-it needs the
6464   // location right before the argument, the argument location can be in a
6465   // macro only if it is at the beginning of the macro.
6466   while (ArgLoc.isMacroID() &&
6467          S.getSourceManager().isAtStartOfImmediateMacroExpansion(ArgLoc)) {
6468     ArgLoc = S.getSourceManager().getImmediateExpansionRange(ArgLoc).first;
6469   }
6470
6471   if (LParen.isMacroID())
6472     return;
6473
6474   LParen = ArgLoc.getLocWithOffset(-1);
6475
6476   S.Diag(CE->getLocStart(), diag::note_remove_move)
6477       << FixItHint::CreateRemoval(SourceRange(CallBegin, LParen))
6478       << FixItHint::CreateRemoval(SourceRange(RParen, RParen));
6479 }
6480
6481 static void CheckForNullPointerDereference(Sema &S, const Expr *E) {
6482   // Check to see if we are dereferencing a null pointer.  If so, this is
6483   // undefined behavior, so warn about it.  This only handles the pattern
6484   // "*null", which is a very syntactic check.
6485   if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E->IgnoreParenCasts()))
6486     if (UO->getOpcode() == UO_Deref &&
6487         UO->getSubExpr()->IgnoreParenCasts()->
6488         isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)) {
6489     S.DiagRuntimeBehavior(UO->getOperatorLoc(), UO,
6490                           S.PDiag(diag::warn_binding_null_to_reference)
6491                             << UO->getSubExpr()->getSourceRange());
6492   }
6493 }
6494
6495 MaterializeTemporaryExpr *
6496 Sema::CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
6497                                      bool BoundToLvalueReference) {
6498   auto MTE = new (Context)
6499       MaterializeTemporaryExpr(T, Temporary, BoundToLvalueReference);
6500
6501   // Order an ExprWithCleanups for lifetime marks.
6502   //
6503   // TODO: It'll be good to have a single place to check the access of the
6504   // destructor and generate ExprWithCleanups for various uses. Currently these
6505   // are done in both CreateMaterializeTemporaryExpr and MaybeBindToTemporary,
6506   // but there may be a chance to merge them.
6507   Cleanup.setExprNeedsCleanups(false);
6508   return MTE;
6509 }
6510
6511 ExprResult Sema::TemporaryMaterializationConversion(Expr *E) {
6512   // In C++98, we don't want to implicitly create an xvalue.
6513   // FIXME: This means that AST consumers need to deal with "prvalues" that
6514   // denote materialized temporaries. Maybe we should add another ValueKind
6515   // for "xvalue pretending to be a prvalue" for C++98 support.
6516   if (!E->isRValue() || !getLangOpts().CPlusPlus11)
6517     return E;
6518
6519   // C++1z [conv.rval]/1: T shall be a complete type.
6520   // FIXME: Does this ever matter (can we form a prvalue of incomplete type)?
6521   // If so, we should check for a non-abstract class type here too.
6522   QualType T = E->getType();
6523   if (RequireCompleteType(E->getExprLoc(), T, diag::err_incomplete_type))
6524     return ExprError();
6525
6526   return CreateMaterializeTemporaryExpr(E->getType(), E, false);
6527 }
6528
6529 ExprResult
6530 InitializationSequence::Perform(Sema &S,
6531                                 const InitializedEntity &Entity,
6532                                 const InitializationKind &Kind,
6533                                 MultiExprArg Args,
6534                                 QualType *ResultType) {
6535   if (Failed()) {
6536     Diagnose(S, Entity, Kind, Args);
6537     return ExprError();
6538   }
6539   if (!ZeroInitializationFixit.empty()) {
6540     unsigned DiagID = diag::err_default_init_const;
6541     if (Decl *D = Entity.getDecl())
6542       if (S.getLangOpts().MSVCCompat && D->hasAttr<SelectAnyAttr>())
6543         DiagID = diag::ext_default_init_const;
6544
6545     // The initialization would have succeeded with this fixit. Since the fixit
6546     // is on the error, we need to build a valid AST in this case, so this isn't
6547     // handled in the Failed() branch above.
6548     QualType DestType = Entity.getType();
6549     S.Diag(Kind.getLocation(), DiagID)
6550         << DestType << (bool)DestType->getAs<RecordType>()
6551         << FixItHint::CreateInsertion(ZeroInitializationFixitLoc,
6552                                       ZeroInitializationFixit);
6553   }
6554
6555   if (getKind() == DependentSequence) {
6556     // If the declaration is a non-dependent, incomplete array type
6557     // that has an initializer, then its type will be completed once
6558     // the initializer is instantiated.
6559     if (ResultType && !Entity.getType()->isDependentType() &&
6560         Args.size() == 1) {
6561       QualType DeclType = Entity.getType();
6562       if (const IncompleteArrayType *ArrayT
6563                            = S.Context.getAsIncompleteArrayType(DeclType)) {
6564         // FIXME: We don't currently have the ability to accurately
6565         // compute the length of an initializer list without
6566         // performing full type-checking of the initializer list
6567         // (since we have to determine where braces are implicitly
6568         // introduced and such).  So, we fall back to making the array
6569         // type a dependently-sized array type with no specified
6570         // bound.
6571         if (isa<InitListExpr>((Expr *)Args[0])) {
6572           SourceRange Brackets;
6573
6574           // Scavange the location of the brackets from the entity, if we can.
6575           if (auto *DD = dyn_cast_or_null<DeclaratorDecl>(Entity.getDecl())) {
6576             if (TypeSourceInfo *TInfo = DD->getTypeSourceInfo()) {
6577               TypeLoc TL = TInfo->getTypeLoc();
6578               if (IncompleteArrayTypeLoc ArrayLoc =
6579                       TL.getAs<IncompleteArrayTypeLoc>())
6580                 Brackets = ArrayLoc.getBracketsRange();
6581             }
6582           }
6583
6584           *ResultType
6585             = S.Context.getDependentSizedArrayType(ArrayT->getElementType(),
6586                                                    /*NumElts=*/nullptr,
6587                                                    ArrayT->getSizeModifier(),
6588                                        ArrayT->getIndexTypeCVRQualifiers(),
6589                                                    Brackets);
6590         }
6591
6592       }
6593     }
6594     if (Kind.getKind() == InitializationKind::IK_Direct &&
6595         !Kind.isExplicitCast()) {
6596       // Rebuild the ParenListExpr.
6597       SourceRange ParenRange = Kind.getParenRange();
6598       return S.ActOnParenListExpr(ParenRange.getBegin(), ParenRange.getEnd(),
6599                                   Args);
6600     }
6601     assert(Kind.getKind() == InitializationKind::IK_Copy ||
6602            Kind.isExplicitCast() ||
6603            Kind.getKind() == InitializationKind::IK_DirectList);
6604     return ExprResult(Args[0]);
6605   }
6606
6607   // No steps means no initialization.
6608   if (Steps.empty())
6609     return ExprResult((Expr *)nullptr);
6610
6611   if (S.getLangOpts().CPlusPlus11 && Entity.getType()->isReferenceType() &&
6612       Args.size() == 1 && isa<InitListExpr>(Args[0]) &&
6613       !Entity.isParameterKind()) {
6614     // Produce a C++98 compatibility warning if we are initializing a reference
6615     // from an initializer list. For parameters, we produce a better warning
6616     // elsewhere.
6617     Expr *Init = Args[0];
6618     S.Diag(Init->getLocStart(), diag::warn_cxx98_compat_reference_list_init)
6619       << Init->getSourceRange();
6620   }
6621
6622   // OpenCL v2.0 s6.13.11.1. atomic variables can be initialized in global scope
6623   QualType ETy = Entity.getType();
6624   Qualifiers TyQualifiers = ETy.getQualifiers();
6625   bool HasGlobalAS = TyQualifiers.hasAddressSpace() &&
6626                      TyQualifiers.getAddressSpace() == LangAS::opencl_global;
6627
6628   if (S.getLangOpts().OpenCLVersion >= 200 &&
6629       ETy->isAtomicType() && !HasGlobalAS &&
6630       Entity.getKind() == InitializedEntity::EK_Variable && Args.size() > 0) {
6631     S.Diag(Args[0]->getLocStart(), diag::err_opencl_atomic_init) << 1 <<
6632     SourceRange(Entity.getDecl()->getLocStart(), Args[0]->getLocEnd());
6633     return ExprError();
6634   }
6635
6636   // Diagnose cases where we initialize a pointer to an array temporary, and the
6637   // pointer obviously outlives the temporary.
6638   if (Args.size() == 1 && Args[0]->getType()->isArrayType() &&
6639       Entity.getType()->isPointerType() &&
6640       InitializedEntityOutlivesFullExpression(Entity)) {
6641     const Expr *Init = Args[0]->skipRValueSubobjectAdjustments();
6642     if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Init))
6643       Init = MTE->GetTemporaryExpr();
6644     Expr::LValueClassification Kind = Init->ClassifyLValue(S.Context);
6645     if (Kind == Expr::LV_ClassTemporary || Kind == Expr::LV_ArrayTemporary)
6646       S.Diag(Init->getLocStart(), diag::warn_temporary_array_to_pointer_decay)
6647         << Init->getSourceRange();
6648   }
6649
6650   QualType DestType = Entity.getType().getNonReferenceType();
6651   // FIXME: Ugly hack around the fact that Entity.getType() is not
6652   // the same as Entity.getDecl()->getType() in cases involving type merging,
6653   //  and we want latter when it makes sense.
6654   if (ResultType)
6655     *ResultType = Entity.getDecl() ? Entity.getDecl()->getType() :
6656                                      Entity.getType();
6657
6658   ExprResult CurInit((Expr *)nullptr);
6659   SmallVector<Expr*, 4> ArrayLoopCommonExprs;
6660
6661   // For initialization steps that start with a single initializer,
6662   // grab the only argument out the Args and place it into the "current"
6663   // initializer.
6664   switch (Steps.front().Kind) {
6665   case SK_ResolveAddressOfOverloadedFunction:
6666   case SK_CastDerivedToBaseRValue:
6667   case SK_CastDerivedToBaseXValue:
6668   case SK_CastDerivedToBaseLValue:
6669   case SK_BindReference:
6670   case SK_BindReferenceToTemporary:
6671   case SK_FinalCopy:
6672   case SK_ExtraneousCopyToTemporary:
6673   case SK_UserConversion:
6674   case SK_QualificationConversionLValue:
6675   case SK_QualificationConversionXValue:
6676   case SK_QualificationConversionRValue:
6677   case SK_AtomicConversion:
6678   case SK_LValueToRValue:
6679   case SK_ConversionSequence:
6680   case SK_ConversionSequenceNoNarrowing:
6681   case SK_ListInitialization:
6682   case SK_UnwrapInitList:
6683   case SK_RewrapInitList:
6684   case SK_CAssignment:
6685   case SK_StringInit:
6686   case SK_ObjCObjectConversion:
6687   case SK_ArrayLoopIndex:
6688   case SK_ArrayLoopInit:
6689   case SK_ArrayInit:
6690   case SK_GNUArrayInit:
6691   case SK_ParenthesizedArrayInit:
6692   case SK_PassByIndirectCopyRestore:
6693   case SK_PassByIndirectRestore:
6694   case SK_ProduceObjCObject:
6695   case SK_StdInitializerList:
6696   case SK_OCLSamplerInit:
6697   case SK_OCLZeroEvent:
6698   case SK_OCLZeroQueue: {
6699     assert(Args.size() == 1);
6700     CurInit = Args[0];
6701     if (!CurInit.get()) return ExprError();
6702     break;
6703   }
6704
6705   case SK_ConstructorInitialization:
6706   case SK_ConstructorInitializationFromList:
6707   case SK_StdInitializerListConstructorCall:
6708   case SK_ZeroInitialization:
6709     break;
6710   }
6711
6712   // Promote from an unevaluated context to an unevaluated list context in
6713   // C++11 list-initialization; we need to instantiate entities usable in
6714   // constant expressions here in order to perform narrowing checks =(
6715   EnterExpressionEvaluationContext Evaluated(
6716       S, EnterExpressionEvaluationContext::InitList,
6717       CurInit.get() && isa<InitListExpr>(CurInit.get()));
6718
6719   // C++ [class.abstract]p2:
6720   //   no objects of an abstract class can be created except as subobjects
6721   //   of a class derived from it
6722   auto checkAbstractType = [&](QualType T) -> bool {
6723     if (Entity.getKind() == InitializedEntity::EK_Base ||
6724         Entity.getKind() == InitializedEntity::EK_Delegating)
6725       return false;
6726     return S.RequireNonAbstractType(Kind.getLocation(), T,
6727                                     diag::err_allocation_of_abstract_type);
6728   };
6729
6730   // Walk through the computed steps for the initialization sequence,
6731   // performing the specified conversions along the way.
6732   bool ConstructorInitRequiresZeroInit = false;
6733   for (step_iterator Step = step_begin(), StepEnd = step_end();
6734        Step != StepEnd; ++Step) {
6735     if (CurInit.isInvalid())
6736       return ExprError();
6737
6738     QualType SourceType = CurInit.get() ? CurInit.get()->getType() : QualType();
6739
6740     switch (Step->Kind) {
6741     case SK_ResolveAddressOfOverloadedFunction:
6742       // Overload resolution determined which function invoke; update the
6743       // initializer to reflect that choice.
6744       S.CheckAddressOfMemberAccess(CurInit.get(), Step->Function.FoundDecl);
6745       if (S.DiagnoseUseOfDecl(Step->Function.FoundDecl, Kind.getLocation()))
6746         return ExprError();
6747       CurInit = S.FixOverloadedFunctionReference(CurInit,
6748                                                  Step->Function.FoundDecl,
6749                                                  Step->Function.Function);
6750       break;
6751
6752     case SK_CastDerivedToBaseRValue:
6753     case SK_CastDerivedToBaseXValue:
6754     case SK_CastDerivedToBaseLValue: {
6755       // We have a derived-to-base cast that produces either an rvalue or an
6756       // lvalue. Perform that cast.
6757
6758       CXXCastPath BasePath;
6759
6760       // Casts to inaccessible base classes are allowed with C-style casts.
6761       bool IgnoreBaseAccess = Kind.isCStyleOrFunctionalCast();
6762       if (S.CheckDerivedToBaseConversion(SourceType, Step->Type,
6763                                          CurInit.get()->getLocStart(),
6764                                          CurInit.get()->getSourceRange(),
6765                                          &BasePath, IgnoreBaseAccess))
6766         return ExprError();
6767
6768       ExprValueKind VK =
6769           Step->Kind == SK_CastDerivedToBaseLValue ?
6770               VK_LValue :
6771               (Step->Kind == SK_CastDerivedToBaseXValue ?
6772                    VK_XValue :
6773                    VK_RValue);
6774       CurInit =
6775           ImplicitCastExpr::Create(S.Context, Step->Type, CK_DerivedToBase,
6776                                    CurInit.get(), &BasePath, VK);
6777       break;
6778     }
6779
6780     case SK_BindReference:
6781       // Reference binding does not have any corresponding ASTs.
6782
6783       // Check exception specifications
6784       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
6785         return ExprError();
6786
6787       // We don't check for e.g. function pointers here, since address
6788       // availability checks should only occur when the function first decays
6789       // into a pointer or reference.
6790       if (CurInit.get()->getType()->isFunctionProtoType()) {
6791         if (auto *DRE = dyn_cast<DeclRefExpr>(CurInit.get()->IgnoreParens())) {
6792           if (auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
6793             if (!S.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
6794                                                      DRE->getLocStart()))
6795               return ExprError();
6796           }
6797         }
6798       }
6799
6800       // Even though we didn't materialize a temporary, the binding may still
6801       // extend the lifetime of a temporary. This happens if we bind a reference
6802       // to the result of a cast to reference type.
6803       if (const InitializedEntity *ExtendingEntity =
6804               getEntityForTemporaryLifetimeExtension(&Entity))
6805         if (performReferenceExtension(CurInit.get(), ExtendingEntity))
6806           warnOnLifetimeExtension(S, Entity, CurInit.get(),
6807                                   /*IsInitializerList=*/false,
6808                                   ExtendingEntity->getDecl());
6809
6810       CheckForNullPointerDereference(S, CurInit.get());
6811       break;
6812
6813     case SK_BindReferenceToTemporary: {
6814       // Make sure the "temporary" is actually an rvalue.
6815       assert(CurInit.get()->isRValue() && "not a temporary");
6816
6817       // Check exception specifications
6818       if (S.CheckExceptionSpecCompatibility(CurInit.get(), DestType))
6819         return ExprError();
6820
6821       // Materialize the temporary into memory.
6822       MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
6823           Step->Type, CurInit.get(), Entity.getType()->isLValueReferenceType());
6824
6825       // Maybe lifetime-extend the temporary's subobjects to match the
6826       // entity's lifetime.
6827       if (const InitializedEntity *ExtendingEntity =
6828               getEntityForTemporaryLifetimeExtension(&Entity))
6829         if (performReferenceExtension(MTE, ExtendingEntity))
6830           warnOnLifetimeExtension(S, Entity, CurInit.get(),
6831                                   /*IsInitializerList=*/false,
6832                                   ExtendingEntity->getDecl());
6833
6834       // If we're extending this temporary to automatic storage duration -- we
6835       // need to register its cleanup during the full-expression's cleanups.
6836       if (MTE->getStorageDuration() == SD_Automatic &&
6837           MTE->getType().isDestructedType())
6838         S.Cleanup.setExprNeedsCleanups(true);
6839
6840       CurInit = MTE;
6841       break;
6842     }
6843
6844     case SK_FinalCopy:
6845       if (checkAbstractType(Step->Type))
6846         return ExprError();
6847
6848       // If the overall initialization is initializing a temporary, we already
6849       // bound our argument if it was necessary to do so. If not (if we're
6850       // ultimately initializing a non-temporary), our argument needs to be
6851       // bound since it's initializing a function parameter.
6852       // FIXME: This is a mess. Rationalize temporary destruction.
6853       if (!shouldBindAsTemporary(Entity))
6854         CurInit = S.MaybeBindToTemporary(CurInit.get());
6855       CurInit = CopyObject(S, Step->Type, Entity, CurInit,
6856                            /*IsExtraneousCopy=*/false);
6857       break;
6858
6859     case SK_ExtraneousCopyToTemporary:
6860       CurInit = CopyObject(S, Step->Type, Entity, CurInit,
6861                            /*IsExtraneousCopy=*/true);
6862       break;
6863
6864     case SK_UserConversion: {
6865       // We have a user-defined conversion that invokes either a constructor
6866       // or a conversion function.
6867       CastKind CastKind;
6868       FunctionDecl *Fn = Step->Function.Function;
6869       DeclAccessPair FoundFn = Step->Function.FoundDecl;
6870       bool HadMultipleCandidates = Step->Function.HadMultipleCandidates;
6871       bool CreatedObject = false;
6872       if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(Fn)) {
6873         // Build a call to the selected constructor.
6874         SmallVector<Expr*, 8> ConstructorArgs;
6875         SourceLocation Loc = CurInit.get()->getLocStart();
6876
6877         // Determine the arguments required to actually perform the constructor
6878         // call.
6879         Expr *Arg = CurInit.get();
6880         if (S.CompleteConstructorCall(Constructor,
6881                                       MultiExprArg(&Arg, 1),
6882                                       Loc, ConstructorArgs))
6883           return ExprError();
6884
6885         // Build an expression that constructs a temporary.
6886         CurInit = S.BuildCXXConstructExpr(Loc, Step->Type,
6887                                           FoundFn, Constructor,
6888                                           ConstructorArgs,
6889                                           HadMultipleCandidates,
6890                                           /*ListInit*/ false,
6891                                           /*StdInitListInit*/ false,
6892                                           /*ZeroInit*/ false,
6893                                           CXXConstructExpr::CK_Complete,
6894                                           SourceRange());
6895         if (CurInit.isInvalid())
6896           return ExprError();
6897
6898         S.CheckConstructorAccess(Kind.getLocation(), Constructor, FoundFn,
6899                                  Entity);
6900         if (S.DiagnoseUseOfDecl(FoundFn, Kind.getLocation()))
6901           return ExprError();
6902
6903         CastKind = CK_ConstructorConversion;
6904         CreatedObject = true;
6905       } else {
6906         // Build a call to the conversion function.
6907         CXXConversionDecl *Conversion = cast<CXXConversionDecl>(Fn);
6908         S.CheckMemberOperatorAccess(Kind.getLocation(), CurInit.get(), nullptr,
6909                                     FoundFn);
6910         if (S.DiagnoseUseOfDecl(FoundFn, Kind.getLocation()))
6911           return ExprError();
6912
6913         // FIXME: Should we move this initialization into a separate
6914         // derived-to-base conversion? I believe the answer is "no", because
6915         // we don't want to turn off access control here for c-style casts.
6916         CurInit = S.PerformObjectArgumentInitialization(CurInit.get(),
6917                                                         /*Qualifier=*/nullptr,
6918                                                         FoundFn, Conversion);
6919         if (CurInit.isInvalid())
6920           return ExprError();
6921
6922         // Build the actual call to the conversion function.
6923         CurInit = S.BuildCXXMemberCallExpr(CurInit.get(), FoundFn, Conversion,
6924                                            HadMultipleCandidates);
6925         if (CurInit.isInvalid())
6926           return ExprError();
6927
6928         CastKind = CK_UserDefinedConversion;
6929         CreatedObject = Conversion->getReturnType()->isRecordType();
6930       }
6931
6932       if (CreatedObject && checkAbstractType(CurInit.get()->getType()))
6933         return ExprError();
6934
6935       CurInit = ImplicitCastExpr::Create(S.Context, CurInit.get()->getType(),
6936                                          CastKind, CurInit.get(), nullptr,
6937                                          CurInit.get()->getValueKind());
6938
6939       if (shouldBindAsTemporary(Entity))
6940         // The overall entity is temporary, so this expression should be
6941         // destroyed at the end of its full-expression.
6942         CurInit = S.MaybeBindToTemporary(CurInit.getAs<Expr>());
6943       else if (CreatedObject && shouldDestroyEntity(Entity)) {
6944         // The object outlasts the full-expression, but we need to prepare for
6945         // a destructor being run on it.
6946         // FIXME: It makes no sense to do this here. This should happen
6947         // regardless of how we initialized the entity.
6948         QualType T = CurInit.get()->getType();
6949         if (const RecordType *Record = T->getAs<RecordType>()) {
6950           CXXDestructorDecl *Destructor
6951             = S.LookupDestructor(cast<CXXRecordDecl>(Record->getDecl()));
6952           S.CheckDestructorAccess(CurInit.get()->getLocStart(), Destructor,
6953                                   S.PDiag(diag::err_access_dtor_temp) << T);
6954           S.MarkFunctionReferenced(CurInit.get()->getLocStart(), Destructor);
6955           if (S.DiagnoseUseOfDecl(Destructor, CurInit.get()->getLocStart()))
6956             return ExprError();
6957         }
6958       }
6959       break;
6960     }
6961
6962     case SK_QualificationConversionLValue:
6963     case SK_QualificationConversionXValue:
6964     case SK_QualificationConversionRValue: {
6965       // Perform a qualification conversion; these can never go wrong.
6966       ExprValueKind VK =
6967           Step->Kind == SK_QualificationConversionLValue ?
6968               VK_LValue :
6969               (Step->Kind == SK_QualificationConversionXValue ?
6970                    VK_XValue :
6971                    VK_RValue);
6972       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type, CK_NoOp, VK);
6973       break;
6974     }
6975
6976     case SK_AtomicConversion: {
6977       assert(CurInit.get()->isRValue() && "cannot convert glvalue to atomic");
6978       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
6979                                     CK_NonAtomicToAtomic, VK_RValue);
6980       break;
6981     }
6982
6983     case SK_LValueToRValue: {
6984       assert(CurInit.get()->isGLValue() && "cannot load from a prvalue");
6985       CurInit = ImplicitCastExpr::Create(S.Context, Step->Type,
6986                                          CK_LValueToRValue, CurInit.get(),
6987                                          /*BasePath=*/nullptr, VK_RValue);
6988       break;
6989     }
6990
6991     case SK_ConversionSequence:
6992     case SK_ConversionSequenceNoNarrowing: {
6993       Sema::CheckedConversionKind CCK
6994         = Kind.isCStyleCast()? Sema::CCK_CStyleCast
6995         : Kind.isFunctionalCast()? Sema::CCK_FunctionalCast
6996         : Kind.isExplicitCast()? Sema::CCK_OtherCast
6997         : Sema::CCK_ImplicitConversion;
6998       ExprResult CurInitExprRes =
6999         S.PerformImplicitConversion(CurInit.get(), Step->Type, *Step->ICS,
7000                                     getAssignmentAction(Entity), CCK);
7001       if (CurInitExprRes.isInvalid())
7002         return ExprError();
7003
7004       S.DiscardMisalignedMemberAddress(Step->Type.getTypePtr(), CurInit.get());
7005
7006       CurInit = CurInitExprRes;
7007
7008       if (Step->Kind == SK_ConversionSequenceNoNarrowing &&
7009           S.getLangOpts().CPlusPlus)
7010         DiagnoseNarrowingInInitList(S, *Step->ICS, SourceType, Entity.getType(),
7011                                     CurInit.get());
7012
7013       break;
7014     }
7015
7016     case SK_ListInitialization: {
7017       if (checkAbstractType(Step->Type))
7018         return ExprError();
7019
7020       InitListExpr *InitList = cast<InitListExpr>(CurInit.get());
7021       // If we're not initializing the top-level entity, we need to create an
7022       // InitializeTemporary entity for our target type.
7023       QualType Ty = Step->Type;
7024       bool IsTemporary = !S.Context.hasSameType(Entity.getType(), Ty);
7025       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(Ty);
7026       InitializedEntity InitEntity = IsTemporary ? TempEntity : Entity;
7027       InitListChecker PerformInitList(S, InitEntity,
7028           InitList, Ty, /*VerifyOnly=*/false,
7029           /*TreatUnavailableAsInvalid=*/false);
7030       if (PerformInitList.HadError())
7031         return ExprError();
7032
7033       // Hack: We must update *ResultType if available in order to set the
7034       // bounds of arrays, e.g. in 'int ar[] = {1, 2, 3};'.
7035       // Worst case: 'const int (&arref)[] = {1, 2, 3};'.
7036       if (ResultType &&
7037           ResultType->getNonReferenceType()->isIncompleteArrayType()) {
7038         if ((*ResultType)->isRValueReferenceType())
7039           Ty = S.Context.getRValueReferenceType(Ty);
7040         else if ((*ResultType)->isLValueReferenceType())
7041           Ty = S.Context.getLValueReferenceType(Ty,
7042             (*ResultType)->getAs<LValueReferenceType>()->isSpelledAsLValue());
7043         *ResultType = Ty;
7044       }
7045
7046       InitListExpr *StructuredInitList =
7047           PerformInitList.getFullyStructuredList();
7048       CurInit.get();
7049       CurInit = shouldBindAsTemporary(InitEntity)
7050           ? S.MaybeBindToTemporary(StructuredInitList)
7051           : StructuredInitList;
7052       break;
7053     }
7054
7055     case SK_ConstructorInitializationFromList: {
7056       if (checkAbstractType(Step->Type))
7057         return ExprError();
7058
7059       // When an initializer list is passed for a parameter of type "reference
7060       // to object", we don't get an EK_Temporary entity, but instead an
7061       // EK_Parameter entity with reference type.
7062       // FIXME: This is a hack. What we really should do is create a user
7063       // conversion step for this case, but this makes it considerably more
7064       // complicated. For now, this will do.
7065       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(
7066                                         Entity.getType().getNonReferenceType());
7067       bool UseTemporary = Entity.getType()->isReferenceType();
7068       assert(Args.size() == 1 && "expected a single argument for list init");
7069       InitListExpr *InitList = cast<InitListExpr>(Args[0]);
7070       S.Diag(InitList->getExprLoc(), diag::warn_cxx98_compat_ctor_list_init)
7071         << InitList->getSourceRange();
7072       MultiExprArg Arg(InitList->getInits(), InitList->getNumInits());
7073       CurInit = PerformConstructorInitialization(S, UseTemporary ? TempEntity :
7074                                                                    Entity,
7075                                                  Kind, Arg, *Step,
7076                                                ConstructorInitRequiresZeroInit,
7077                                                /*IsListInitialization*/true,
7078                                                /*IsStdInitListInit*/false,
7079                                                InitList->getLBraceLoc(),
7080                                                InitList->getRBraceLoc());
7081       break;
7082     }
7083
7084     case SK_UnwrapInitList:
7085       CurInit = cast<InitListExpr>(CurInit.get())->getInit(0);
7086       break;
7087
7088     case SK_RewrapInitList: {
7089       Expr *E = CurInit.get();
7090       InitListExpr *Syntactic = Step->WrappingSyntacticList;
7091       InitListExpr *ILE = new (S.Context) InitListExpr(S.Context,
7092           Syntactic->getLBraceLoc(), E, Syntactic->getRBraceLoc());
7093       ILE->setSyntacticForm(Syntactic);
7094       ILE->setType(E->getType());
7095       ILE->setValueKind(E->getValueKind());
7096       CurInit = ILE;
7097       break;
7098     }
7099
7100     case SK_ConstructorInitialization:
7101     case SK_StdInitializerListConstructorCall: {
7102       if (checkAbstractType(Step->Type))
7103         return ExprError();
7104
7105       // When an initializer list is passed for a parameter of type "reference
7106       // to object", we don't get an EK_Temporary entity, but instead an
7107       // EK_Parameter entity with reference type.
7108       // FIXME: This is a hack. What we really should do is create a user
7109       // conversion step for this case, but this makes it considerably more
7110       // complicated. For now, this will do.
7111       InitializedEntity TempEntity = InitializedEntity::InitializeTemporary(
7112                                         Entity.getType().getNonReferenceType());
7113       bool UseTemporary = Entity.getType()->isReferenceType();
7114       bool IsStdInitListInit =
7115           Step->Kind == SK_StdInitializerListConstructorCall;
7116       Expr *Source = CurInit.get();
7117       CurInit = PerformConstructorInitialization(
7118           S, UseTemporary ? TempEntity : Entity, Kind,
7119           Source ? MultiExprArg(Source) : Args, *Step,
7120           ConstructorInitRequiresZeroInit,
7121           /*IsListInitialization*/ IsStdInitListInit,
7122           /*IsStdInitListInitialization*/ IsStdInitListInit,
7123           /*LBraceLoc*/ SourceLocation(),
7124           /*RBraceLoc*/ SourceLocation());
7125       break;
7126     }
7127
7128     case SK_ZeroInitialization: {
7129       step_iterator NextStep = Step;
7130       ++NextStep;
7131       if (NextStep != StepEnd &&
7132           (NextStep->Kind == SK_ConstructorInitialization ||
7133            NextStep->Kind == SK_ConstructorInitializationFromList)) {
7134         // The need for zero-initialization is recorded directly into
7135         // the call to the object's constructor within the next step.
7136         ConstructorInitRequiresZeroInit = true;
7137       } else if (Kind.getKind() == InitializationKind::IK_Value &&
7138                  S.getLangOpts().CPlusPlus &&
7139                  !Kind.isImplicitValueInit()) {
7140         TypeSourceInfo *TSInfo = Entity.getTypeSourceInfo();
7141         if (!TSInfo)
7142           TSInfo = S.Context.getTrivialTypeSourceInfo(Step->Type,
7143                                                     Kind.getRange().getBegin());
7144
7145         CurInit = new (S.Context) CXXScalarValueInitExpr(
7146             Entity.getType().getNonLValueExprType(S.Context), TSInfo,
7147             Kind.getRange().getEnd());
7148       } else {
7149         CurInit = new (S.Context) ImplicitValueInitExpr(Step->Type);
7150       }
7151       break;
7152     }
7153
7154     case SK_CAssignment: {
7155       QualType SourceType = CurInit.get()->getType();
7156       // Save off the initial CurInit in case we need to emit a diagnostic
7157       ExprResult InitialCurInit = CurInit;
7158       ExprResult Result = CurInit;
7159       Sema::AssignConvertType ConvTy =
7160         S.CheckSingleAssignmentConstraints(Step->Type, Result, true,
7161             Entity.getKind() == InitializedEntity::EK_Parameter_CF_Audited);
7162       if (Result.isInvalid())
7163         return ExprError();
7164       CurInit = Result;
7165
7166       // If this is a call, allow conversion to a transparent union.
7167       ExprResult CurInitExprRes = CurInit;
7168       if (ConvTy != Sema::Compatible &&
7169           Entity.isParameterKind() &&
7170           S.CheckTransparentUnionArgumentConstraints(Step->Type, CurInitExprRes)
7171             == Sema::Compatible)
7172         ConvTy = Sema::Compatible;
7173       if (CurInitExprRes.isInvalid())
7174         return ExprError();
7175       CurInit = CurInitExprRes;
7176
7177       bool Complained;
7178       if (S.DiagnoseAssignmentResult(ConvTy, Kind.getLocation(),
7179                                      Step->Type, SourceType,
7180                                      InitialCurInit.get(),
7181                                      getAssignmentAction(Entity, true),
7182                                      &Complained)) {
7183         PrintInitLocationNote(S, Entity);
7184         return ExprError();
7185       } else if (Complained)
7186         PrintInitLocationNote(S, Entity);
7187       break;
7188     }
7189
7190     case SK_StringInit: {
7191       QualType Ty = Step->Type;
7192       CheckStringInit(CurInit.get(), ResultType ? *ResultType : Ty,
7193                       S.Context.getAsArrayType(Ty), S);
7194       break;
7195     }
7196
7197     case SK_ObjCObjectConversion:
7198       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
7199                           CK_ObjCObjectLValueCast,
7200                           CurInit.get()->getValueKind());
7201       break;
7202
7203     case SK_ArrayLoopIndex: {
7204       Expr *Cur = CurInit.get();
7205       Expr *BaseExpr = new (S.Context)
7206           OpaqueValueExpr(Cur->getExprLoc(), Cur->getType(),
7207                           Cur->getValueKind(), Cur->getObjectKind(), Cur);
7208       Expr *IndexExpr =
7209           new (S.Context) ArrayInitIndexExpr(S.Context.getSizeType());
7210       CurInit = S.CreateBuiltinArraySubscriptExpr(
7211           BaseExpr, Kind.getLocation(), IndexExpr, Kind.getLocation());
7212       ArrayLoopCommonExprs.push_back(BaseExpr);
7213       break;
7214     }
7215
7216     case SK_ArrayLoopInit: {
7217       assert(!ArrayLoopCommonExprs.empty() &&
7218              "mismatched SK_ArrayLoopIndex and SK_ArrayLoopInit");
7219       Expr *Common = ArrayLoopCommonExprs.pop_back_val();
7220       CurInit = new (S.Context) ArrayInitLoopExpr(Step->Type, Common,
7221                                                   CurInit.get());
7222       break;
7223     }
7224
7225     case SK_GNUArrayInit:
7226       // Okay: we checked everything before creating this step. Note that
7227       // this is a GNU extension.
7228       S.Diag(Kind.getLocation(), diag::ext_array_init_copy)
7229         << Step->Type << CurInit.get()->getType()
7230         << CurInit.get()->getSourceRange();
7231       LLVM_FALLTHROUGH;
7232     case SK_ArrayInit:
7233       // If the destination type is an incomplete array type, update the
7234       // type accordingly.
7235       if (ResultType) {
7236         if (const IncompleteArrayType *IncompleteDest
7237                            = S.Context.getAsIncompleteArrayType(Step->Type)) {
7238           if (const ConstantArrayType *ConstantSource
7239                  = S.Context.getAsConstantArrayType(CurInit.get()->getType())) {
7240             *ResultType = S.Context.getConstantArrayType(
7241                                              IncompleteDest->getElementType(),
7242                                              ConstantSource->getSize(),
7243                                              ArrayType::Normal, 0);
7244           }
7245         }
7246       }
7247       break;
7248
7249     case SK_ParenthesizedArrayInit:
7250       // Okay: we checked everything before creating this step. Note that
7251       // this is a GNU extension.
7252       S.Diag(Kind.getLocation(), diag::ext_array_init_parens)
7253         << CurInit.get()->getSourceRange();
7254       break;
7255
7256     case SK_PassByIndirectCopyRestore:
7257     case SK_PassByIndirectRestore:
7258       checkIndirectCopyRestoreSource(S, CurInit.get());
7259       CurInit = new (S.Context) ObjCIndirectCopyRestoreExpr(
7260           CurInit.get(), Step->Type,
7261           Step->Kind == SK_PassByIndirectCopyRestore);
7262       break;
7263
7264     case SK_ProduceObjCObject:
7265       CurInit =
7266           ImplicitCastExpr::Create(S.Context, Step->Type, CK_ARCProduceObject,
7267                                    CurInit.get(), nullptr, VK_RValue);
7268       break;
7269
7270     case SK_StdInitializerList: {
7271       S.Diag(CurInit.get()->getExprLoc(),
7272              diag::warn_cxx98_compat_initializer_list_init)
7273         << CurInit.get()->getSourceRange();
7274
7275       // Materialize the temporary into memory.
7276       MaterializeTemporaryExpr *MTE = S.CreateMaterializeTemporaryExpr(
7277           CurInit.get()->getType(), CurInit.get(),
7278           /*BoundToLvalueReference=*/false);
7279
7280       // Maybe lifetime-extend the array temporary's subobjects to match the
7281       // entity's lifetime.
7282       if (const InitializedEntity *ExtendingEntity =
7283               getEntityForTemporaryLifetimeExtension(&Entity))
7284         if (performReferenceExtension(MTE, ExtendingEntity))
7285           warnOnLifetimeExtension(S, Entity, CurInit.get(),
7286                                   /*IsInitializerList=*/true,
7287                                   ExtendingEntity->getDecl());
7288
7289       // Wrap it in a construction of a std::initializer_list<T>.
7290       CurInit = new (S.Context) CXXStdInitializerListExpr(Step->Type, MTE);
7291
7292       // Bind the result, in case the library has given initializer_list a
7293       // non-trivial destructor.
7294       if (shouldBindAsTemporary(Entity))
7295         CurInit = S.MaybeBindToTemporary(CurInit.get());
7296       break;
7297     }
7298
7299     case SK_OCLSamplerInit: {
7300       // Sampler initialzation have 5 cases:
7301       //   1. function argument passing
7302       //      1a. argument is a file-scope variable
7303       //      1b. argument is a function-scope variable
7304       //      1c. argument is one of caller function's parameters
7305       //   2. variable initialization
7306       //      2a. initializing a file-scope variable
7307       //      2b. initializing a function-scope variable
7308       //
7309       // For file-scope variables, since they cannot be initialized by function
7310       // call of __translate_sampler_initializer in LLVM IR, their references
7311       // need to be replaced by a cast from their literal initializers to
7312       // sampler type. Since sampler variables can only be used in function
7313       // calls as arguments, we only need to replace them when handling the
7314       // argument passing.
7315       assert(Step->Type->isSamplerT() &&
7316              "Sampler initialization on non-sampler type.");
7317       Expr *Init = CurInit.get();
7318       QualType SourceType = Init->getType();
7319       // Case 1
7320       if (Entity.isParameterKind()) {
7321         if (!SourceType->isSamplerT() && !SourceType->isIntegerType()) {
7322           S.Diag(Kind.getLocation(), diag::err_sampler_argument_required)
7323             << SourceType;
7324           break;
7325         } else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Init)) {
7326           auto Var = cast<VarDecl>(DRE->getDecl());
7327           // Case 1b and 1c
7328           // No cast from integer to sampler is needed.
7329           if (!Var->hasGlobalStorage()) {
7330             CurInit = ImplicitCastExpr::Create(S.Context, Step->Type,
7331                                                CK_LValueToRValue, Init,
7332                                                /*BasePath=*/nullptr, VK_RValue);
7333             break;
7334           }
7335           // Case 1a
7336           // For function call with a file-scope sampler variable as argument,
7337           // get the integer literal.
7338           // Do not diagnose if the file-scope variable does not have initializer
7339           // since this has already been diagnosed when parsing the variable
7340           // declaration.
7341           if (!Var->getInit() || !isa<ImplicitCastExpr>(Var->getInit()))
7342             break;
7343           Init = cast<ImplicitCastExpr>(const_cast<Expr*>(
7344             Var->getInit()))->getSubExpr();
7345           SourceType = Init->getType();
7346         }
7347       } else {
7348         // Case 2
7349         // Check initializer is 32 bit integer constant.
7350         // If the initializer is taken from global variable, do not diagnose since
7351         // this has already been done when parsing the variable declaration.
7352         if (!Init->isConstantInitializer(S.Context, false))
7353           break;
7354
7355         if (!SourceType->isIntegerType() ||
7356             32 != S.Context.getIntWidth(SourceType)) {
7357           S.Diag(Kind.getLocation(), diag::err_sampler_initializer_not_integer)
7358             << SourceType;
7359           break;
7360         }
7361
7362         llvm::APSInt Result;
7363         Init->EvaluateAsInt(Result, S.Context);
7364         const uint64_t SamplerValue = Result.getLimitedValue();
7365         // 32-bit value of sampler's initializer is interpreted as
7366         // bit-field with the following structure:
7367         // |unspecified|Filter|Addressing Mode| Normalized Coords|
7368         // |31        6|5    4|3             1|                 0|
7369         // This structure corresponds to enum values of sampler properties
7370         // defined in SPIR spec v1.2 and also opencl-c.h
7371         unsigned AddressingMode  = (0x0E & SamplerValue) >> 1;
7372         unsigned FilterMode      = (0x30 & SamplerValue) >> 4;
7373         if (FilterMode != 1 && FilterMode != 2)
7374           S.Diag(Kind.getLocation(),
7375                  diag::warn_sampler_initializer_invalid_bits)
7376                  << "Filter Mode";
7377         if (AddressingMode > 4)
7378           S.Diag(Kind.getLocation(),
7379                  diag::warn_sampler_initializer_invalid_bits)
7380                  << "Addressing Mode";
7381       }
7382
7383       // Cases 1a, 2a and 2b
7384       // Insert cast from integer to sampler.
7385       CurInit = S.ImpCastExprToType(Init, S.Context.OCLSamplerTy,
7386                                       CK_IntToOCLSampler);
7387       break;
7388     }
7389     case SK_OCLZeroEvent: {
7390       assert(Step->Type->isEventT() &&
7391              "Event initialization on non-event type.");
7392
7393       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
7394                                     CK_ZeroToOCLEvent,
7395                                     CurInit.get()->getValueKind());
7396       break;
7397     }
7398     case SK_OCLZeroQueue: {
7399       assert(Step->Type->isQueueT() &&
7400              "Event initialization on non queue type.");
7401
7402       CurInit = S.ImpCastExprToType(CurInit.get(), Step->Type,
7403                                     CK_ZeroToOCLQueue,
7404                                     CurInit.get()->getValueKind());
7405       break;
7406     }
7407     }
7408   }
7409
7410   // Diagnose non-fatal problems with the completed initialization.
7411   if (Entity.getKind() == InitializedEntity::EK_Member &&
7412       cast<FieldDecl>(Entity.getDecl())->isBitField())
7413     S.CheckBitFieldInitialization(Kind.getLocation(),
7414                                   cast<FieldDecl>(Entity.getDecl()),
7415                                   CurInit.get());
7416
7417   // Check for std::move on construction.
7418   if (const Expr *E = CurInit.get()) {
7419     CheckMoveOnConstruction(S, E,
7420                             Entity.getKind() == InitializedEntity::EK_Result);
7421   }
7422
7423   return CurInit;
7424 }
7425
7426 /// Somewhere within T there is an uninitialized reference subobject.
7427 /// Dig it out and diagnose it.
7428 static bool DiagnoseUninitializedReference(Sema &S, SourceLocation Loc,
7429                                            QualType T) {
7430   if (T->isReferenceType()) {
7431     S.Diag(Loc, diag::err_reference_without_init)
7432       << T.getNonReferenceType();
7433     return true;
7434   }
7435
7436   CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
7437   if (!RD || !RD->hasUninitializedReferenceMember())
7438     return false;
7439
7440   for (const auto *FI : RD->fields()) {
7441     if (FI->isUnnamedBitfield())
7442       continue;
7443
7444     if (DiagnoseUninitializedReference(S, FI->getLocation(), FI->getType())) {
7445       S.Diag(Loc, diag::note_value_initialization_here) << RD;
7446       return true;
7447     }
7448   }
7449
7450   for (const auto &BI : RD->bases()) {
7451     if (DiagnoseUninitializedReference(S, BI.getLocStart(), BI.getType())) {
7452       S.Diag(Loc, diag::note_value_initialization_here) << RD;
7453       return true;
7454     }
7455   }
7456
7457   return false;
7458 }
7459
7460
7461 //===----------------------------------------------------------------------===//
7462 // Diagnose initialization failures
7463 //===----------------------------------------------------------------------===//
7464
7465 /// Emit notes associated with an initialization that failed due to a
7466 /// "simple" conversion failure.
7467 static void emitBadConversionNotes(Sema &S, const InitializedEntity &entity,
7468                                    Expr *op) {
7469   QualType destType = entity.getType();
7470   if (destType.getNonReferenceType()->isObjCObjectPointerType() &&
7471       op->getType()->isObjCObjectPointerType()) {
7472
7473     // Emit a possible note about the conversion failing because the
7474     // operand is a message send with a related result type.
7475     S.EmitRelatedResultTypeNote(op);
7476
7477     // Emit a possible note about a return failing because we're
7478     // expecting a related result type.
7479     if (entity.getKind() == InitializedEntity::EK_Result)
7480       S.EmitRelatedResultTypeNoteForReturn(destType);
7481   }
7482 }
7483
7484 static void diagnoseListInit(Sema &S, const InitializedEntity &Entity,
7485                              InitListExpr *InitList) {
7486   QualType DestType = Entity.getType();
7487
7488   QualType E;
7489   if (S.getLangOpts().CPlusPlus11 && S.isStdInitializerList(DestType, &E)) {
7490     QualType ArrayType = S.Context.getConstantArrayType(
7491         E.withConst(),
7492         llvm::APInt(S.Context.getTypeSize(S.Context.getSizeType()),
7493                     InitList->getNumInits()),
7494         clang::ArrayType::Normal, 0);
7495     InitializedEntity HiddenArray =
7496         InitializedEntity::InitializeTemporary(ArrayType);
7497     return diagnoseListInit(S, HiddenArray, InitList);
7498   }
7499
7500   if (DestType->isReferenceType()) {
7501     // A list-initialization failure for a reference means that we tried to
7502     // create a temporary of the inner type (per [dcl.init.list]p3.6) and the
7503     // inner initialization failed.
7504     QualType T = DestType->getAs<ReferenceType>()->getPointeeType();
7505     diagnoseListInit(S, InitializedEntity::InitializeTemporary(T), InitList);
7506     SourceLocation Loc = InitList->getLocStart();
7507     if (auto *D = Entity.getDecl())
7508       Loc = D->getLocation();
7509     S.Diag(Loc, diag::note_in_reference_temporary_list_initializer) << T;
7510     return;
7511   }
7512
7513   InitListChecker DiagnoseInitList(S, Entity, InitList, DestType,
7514                                    /*VerifyOnly=*/false,
7515                                    /*TreatUnavailableAsInvalid=*/false);
7516   assert(DiagnoseInitList.HadError() &&
7517          "Inconsistent init list check result.");
7518 }
7519
7520 bool InitializationSequence::Diagnose(Sema &S,
7521                                       const InitializedEntity &Entity,
7522                                       const InitializationKind &Kind,
7523                                       ArrayRef<Expr *> Args) {
7524   if (!Failed())
7525     return false;
7526
7527   QualType DestType = Entity.getType();
7528   switch (Failure) {
7529   case FK_TooManyInitsForReference:
7530     // FIXME: Customize for the initialized entity?
7531     if (Args.empty()) {
7532       // Dig out the reference subobject which is uninitialized and diagnose it.
7533       // If this is value-initialization, this could be nested some way within
7534       // the target type.
7535       assert(Kind.getKind() == InitializationKind::IK_Value ||
7536              DestType->isReferenceType());
7537       bool Diagnosed =
7538         DiagnoseUninitializedReference(S, Kind.getLocation(), DestType);
7539       assert(Diagnosed && "couldn't find uninitialized reference to diagnose");
7540       (void)Diagnosed;
7541     } else  // FIXME: diagnostic below could be better!
7542       S.Diag(Kind.getLocation(), diag::err_reference_has_multiple_inits)
7543         << SourceRange(Args.front()->getLocStart(), Args.back()->getLocEnd());
7544     break;
7545   case FK_ParenthesizedListInitForReference:
7546     S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
7547       << 1 << Entity.getType() << Args[0]->getSourceRange();
7548     break;
7549
7550   case FK_ArrayNeedsInitList:
7551     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 0;
7552     break;
7553   case FK_ArrayNeedsInitListOrStringLiteral:
7554     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 1;
7555     break;
7556   case FK_ArrayNeedsInitListOrWideStringLiteral:
7557     S.Diag(Kind.getLocation(), diag::err_array_init_not_init_list) << 2;
7558     break;
7559   case FK_NarrowStringIntoWideCharArray:
7560     S.Diag(Kind.getLocation(), diag::err_array_init_narrow_string_into_wchar);
7561     break;
7562   case FK_WideStringIntoCharArray:
7563     S.Diag(Kind.getLocation(), diag::err_array_init_wide_string_into_char);
7564     break;
7565   case FK_IncompatWideStringIntoWideChar:
7566     S.Diag(Kind.getLocation(),
7567            diag::err_array_init_incompat_wide_string_into_wchar);
7568     break;
7569   case FK_ArrayTypeMismatch:
7570   case FK_NonConstantArrayInit:
7571     S.Diag(Kind.getLocation(),
7572            (Failure == FK_ArrayTypeMismatch
7573               ? diag::err_array_init_different_type
7574               : diag::err_array_init_non_constant_array))
7575       << DestType.getNonReferenceType()
7576       << Args[0]->getType()
7577       << Args[0]->getSourceRange();
7578     break;
7579
7580   case FK_VariableLengthArrayHasInitializer:
7581     S.Diag(Kind.getLocation(), diag::err_variable_object_no_init)
7582       << Args[0]->getSourceRange();
7583     break;
7584
7585   case FK_AddressOfOverloadFailed: {
7586     DeclAccessPair Found;
7587     S.ResolveAddressOfOverloadedFunction(Args[0],
7588                                          DestType.getNonReferenceType(),
7589                                          true,
7590                                          Found);
7591     break;
7592   }
7593
7594   case FK_AddressOfUnaddressableFunction: {
7595     auto *FD = cast<FunctionDecl>(cast<DeclRefExpr>(Args[0])->getDecl());
7596     S.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
7597                                         Args[0]->getLocStart());
7598     break;
7599   }
7600
7601   case FK_ReferenceInitOverloadFailed:
7602   case FK_UserConversionOverloadFailed:
7603     switch (FailedOverloadResult) {
7604     case OR_Ambiguous:
7605       if (Failure == FK_UserConversionOverloadFailed)
7606         S.Diag(Kind.getLocation(), diag::err_typecheck_ambiguous_condition)
7607           << Args[0]->getType() << DestType
7608           << Args[0]->getSourceRange();
7609       else
7610         S.Diag(Kind.getLocation(), diag::err_ref_init_ambiguous)
7611           << DestType << Args[0]->getType()
7612           << Args[0]->getSourceRange();
7613
7614       FailedCandidateSet.NoteCandidates(S, OCD_ViableCandidates, Args);
7615       break;
7616
7617     case OR_No_Viable_Function:
7618       if (!S.RequireCompleteType(Kind.getLocation(),
7619                                  DestType.getNonReferenceType(),
7620                           diag::err_typecheck_nonviable_condition_incomplete,
7621                                Args[0]->getType(), Args[0]->getSourceRange()))
7622         S.Diag(Kind.getLocation(), diag::err_typecheck_nonviable_condition)
7623           << (Entity.getKind() == InitializedEntity::EK_Result)
7624           << Args[0]->getType() << Args[0]->getSourceRange()
7625           << DestType.getNonReferenceType();
7626
7627       FailedCandidateSet.NoteCandidates(S, OCD_AllCandidates, Args);
7628       break;
7629
7630     case OR_Deleted: {
7631       S.Diag(Kind.getLocation(), diag::err_typecheck_deleted_function)
7632         << Args[0]->getType() << DestType.getNonReferenceType()
7633         << Args[0]->getSourceRange();
7634       OverloadCandidateSet::iterator Best;
7635       OverloadingResult Ovl
7636         = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
7637       if (Ovl == OR_Deleted) {
7638         S.NoteDeletedFunction(Best->Function);
7639       } else {
7640         llvm_unreachable("Inconsistent overload resolution?");
7641       }
7642       break;
7643     }
7644
7645     case OR_Success:
7646       llvm_unreachable("Conversion did not fail!");
7647     }
7648     break;
7649
7650   case FK_NonConstLValueReferenceBindingToTemporary:
7651     if (isa<InitListExpr>(Args[0])) {
7652       S.Diag(Kind.getLocation(),
7653              diag::err_lvalue_reference_bind_to_initlist)
7654       << DestType.getNonReferenceType().isVolatileQualified()
7655       << DestType.getNonReferenceType()
7656       << Args[0]->getSourceRange();
7657       break;
7658     }
7659     LLVM_FALLTHROUGH;
7660
7661   case FK_NonConstLValueReferenceBindingToUnrelated:
7662     S.Diag(Kind.getLocation(),
7663            Failure == FK_NonConstLValueReferenceBindingToTemporary
7664              ? diag::err_lvalue_reference_bind_to_temporary
7665              : diag::err_lvalue_reference_bind_to_unrelated)
7666       << DestType.getNonReferenceType().isVolatileQualified()
7667       << DestType.getNonReferenceType()
7668       << Args[0]->getType()
7669       << Args[0]->getSourceRange();
7670     break;
7671
7672   case FK_NonConstLValueReferenceBindingToBitfield: {
7673     // We don't necessarily have an unambiguous source bit-field.
7674     FieldDecl *BitField = Args[0]->getSourceBitField();
7675     S.Diag(Kind.getLocation(), diag::err_reference_bind_to_bitfield)
7676       << DestType.isVolatileQualified()
7677       << (BitField ? BitField->getDeclName() : DeclarationName())
7678       << (BitField != nullptr)
7679       << Args[0]->getSourceRange();
7680     if (BitField)
7681       S.Diag(BitField->getLocation(), diag::note_bitfield_decl);
7682     break;
7683   }
7684
7685   case FK_NonConstLValueReferenceBindingToVectorElement:
7686     S.Diag(Kind.getLocation(), diag::err_reference_bind_to_vector_element)
7687       << DestType.isVolatileQualified()
7688       << Args[0]->getSourceRange();
7689     break;
7690
7691   case FK_RValueReferenceBindingToLValue:
7692     S.Diag(Kind.getLocation(), diag::err_lvalue_to_rvalue_ref)
7693       << DestType.getNonReferenceType() << Args[0]->getType()
7694       << Args[0]->getSourceRange();
7695     break;
7696
7697   case FK_ReferenceInitDropsQualifiers: {
7698     QualType SourceType = Args[0]->getType();
7699     QualType NonRefType = DestType.getNonReferenceType();
7700     Qualifiers DroppedQualifiers =
7701         SourceType.getQualifiers() - NonRefType.getQualifiers();
7702
7703     S.Diag(Kind.getLocation(), diag::err_reference_bind_drops_quals)
7704       << SourceType
7705       << NonRefType
7706       << DroppedQualifiers.getCVRQualifiers()
7707       << Args[0]->getSourceRange();
7708     break;
7709   }
7710
7711   case FK_ReferenceInitFailed:
7712     S.Diag(Kind.getLocation(), diag::err_reference_bind_failed)
7713       << DestType.getNonReferenceType()
7714       << Args[0]->isLValue()
7715       << Args[0]->getType()
7716       << Args[0]->getSourceRange();
7717     emitBadConversionNotes(S, Entity, Args[0]);
7718     break;
7719
7720   case FK_ConversionFailed: {
7721     QualType FromType = Args[0]->getType();
7722     PartialDiagnostic PDiag = S.PDiag(diag::err_init_conversion_failed)
7723       << (int)Entity.getKind()
7724       << DestType
7725       << Args[0]->isLValue()
7726       << FromType
7727       << Args[0]->getSourceRange();
7728     S.HandleFunctionTypeMismatch(PDiag, FromType, DestType);
7729     S.Diag(Kind.getLocation(), PDiag);
7730     emitBadConversionNotes(S, Entity, Args[0]);
7731     break;
7732   }
7733
7734   case FK_ConversionFromPropertyFailed:
7735     // No-op. This error has already been reported.
7736     break;
7737
7738   case FK_TooManyInitsForScalar: {
7739     SourceRange R;
7740
7741     auto *InitList = dyn_cast<InitListExpr>(Args[0]);
7742     if (InitList && InitList->getNumInits() >= 1) {
7743       R = SourceRange(InitList->getInit(0)->getLocEnd(), InitList->getLocEnd());
7744     } else {
7745       assert(Args.size() > 1 && "Expected multiple initializers!");
7746       R = SourceRange(Args.front()->getLocEnd(), Args.back()->getLocEnd());
7747     }
7748
7749     R.setBegin(S.getLocForEndOfToken(R.getBegin()));
7750     if (Kind.isCStyleOrFunctionalCast())
7751       S.Diag(Kind.getLocation(), diag::err_builtin_func_cast_more_than_one_arg)
7752         << R;
7753     else
7754       S.Diag(Kind.getLocation(), diag::err_excess_initializers)
7755         << /*scalar=*/2 << R;
7756     break;
7757   }
7758
7759   case FK_ParenthesizedListInitForScalar:
7760     S.Diag(Kind.getLocation(), diag::err_list_init_in_parens)
7761       << 0 << Entity.getType() << Args[0]->getSourceRange();
7762     break;
7763
7764   case FK_ReferenceBindingToInitList:
7765     S.Diag(Kind.getLocation(), diag::err_reference_bind_init_list)
7766       << DestType.getNonReferenceType() << Args[0]->getSourceRange();
7767     break;
7768
7769   case FK_InitListBadDestinationType:
7770     S.Diag(Kind.getLocation(), diag::err_init_list_bad_dest_type)
7771       << (DestType->isRecordType()) << DestType << Args[0]->getSourceRange();
7772     break;
7773
7774   case FK_ListConstructorOverloadFailed:
7775   case FK_ConstructorOverloadFailed: {
7776     SourceRange ArgsRange;
7777     if (Args.size())
7778       ArgsRange = SourceRange(Args.front()->getLocStart(),
7779                               Args.back()->getLocEnd());
7780
7781     if (Failure == FK_ListConstructorOverloadFailed) {
7782       assert(Args.size() == 1 &&
7783              "List construction from other than 1 argument.");
7784       InitListExpr *InitList = cast<InitListExpr>(Args[0]);
7785       Args = MultiExprArg(InitList->getInits(), InitList->getNumInits());
7786     }
7787
7788     // FIXME: Using "DestType" for the entity we're printing is probably
7789     // bad.
7790     switch (FailedOverloadResult) {
7791       case OR_Ambiguous:
7792         S.Diag(Kind.getLocation(), diag::err_ovl_ambiguous_init)
7793           << DestType << ArgsRange;
7794         FailedCandidateSet.NoteCandidates(S, OCD_ViableCandidates, Args);
7795         break;
7796
7797       case OR_No_Viable_Function:
7798         if (Kind.getKind() == InitializationKind::IK_Default &&
7799             (Entity.getKind() == InitializedEntity::EK_Base ||
7800              Entity.getKind() == InitializedEntity::EK_Member) &&
7801             isa<CXXConstructorDecl>(S.CurContext)) {
7802           // This is implicit default initialization of a member or
7803           // base within a constructor. If no viable function was
7804           // found, notify the user that they need to explicitly
7805           // initialize this base/member.
7806           CXXConstructorDecl *Constructor
7807             = cast<CXXConstructorDecl>(S.CurContext);
7808           const CXXRecordDecl *InheritedFrom = nullptr;
7809           if (auto Inherited = Constructor->getInheritedConstructor())
7810             InheritedFrom = Inherited.getShadowDecl()->getNominatedBaseClass();
7811           if (Entity.getKind() == InitializedEntity::EK_Base) {
7812             S.Diag(Kind.getLocation(), diag::err_missing_default_ctor)
7813               << (InheritedFrom ? 2 : Constructor->isImplicit() ? 1 : 0)
7814               << S.Context.getTypeDeclType(Constructor->getParent())
7815               << /*base=*/0
7816               << Entity.getType()
7817               << InheritedFrom;
7818
7819             RecordDecl *BaseDecl
7820               = Entity.getBaseSpecifier()->getType()->getAs<RecordType>()
7821                                                                   ->getDecl();
7822             S.Diag(BaseDecl->getLocation(), diag::note_previous_decl)
7823               << S.Context.getTagDeclType(BaseDecl);
7824           } else {
7825             S.Diag(Kind.getLocation(), diag::err_missing_default_ctor)
7826               << (InheritedFrom ? 2 : Constructor->isImplicit() ? 1 : 0)
7827               << S.Context.getTypeDeclType(Constructor->getParent())
7828               << /*member=*/1
7829               << Entity.getName()
7830               << InheritedFrom;
7831             S.Diag(Entity.getDecl()->getLocation(),
7832                    diag::note_member_declared_at);
7833
7834             if (const RecordType *Record
7835                                  = Entity.getType()->getAs<RecordType>())
7836               S.Diag(Record->getDecl()->getLocation(),
7837                      diag::note_previous_decl)
7838                 << S.Context.getTagDeclType(Record->getDecl());
7839           }
7840           break;
7841         }
7842
7843         S.Diag(Kind.getLocation(), diag::err_ovl_no_viable_function_in_init)
7844           << DestType << ArgsRange;
7845         FailedCandidateSet.NoteCandidates(S, OCD_AllCandidates, Args);
7846         break;
7847
7848       case OR_Deleted: {
7849         OverloadCandidateSet::iterator Best;
7850         OverloadingResult Ovl
7851           = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
7852         if (Ovl != OR_Deleted) {
7853           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
7854             << true << DestType << ArgsRange;
7855           llvm_unreachable("Inconsistent overload resolution?");
7856           break;
7857         }
7858
7859         // If this is a defaulted or implicitly-declared function, then
7860         // it was implicitly deleted. Make it clear that the deletion was
7861         // implicit.
7862         if (S.isImplicitlyDeleted(Best->Function))
7863           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_special_init)
7864             << S.getSpecialMember(cast<CXXMethodDecl>(Best->Function))
7865             << DestType << ArgsRange;
7866         else
7867           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
7868             << true << DestType << ArgsRange;
7869
7870         S.NoteDeletedFunction(Best->Function);
7871         break;
7872       }
7873
7874       case OR_Success:
7875         llvm_unreachable("Conversion did not fail!");
7876     }
7877   }
7878   break;
7879
7880   case FK_DefaultInitOfConst:
7881     if (Entity.getKind() == InitializedEntity::EK_Member &&
7882         isa<CXXConstructorDecl>(S.CurContext)) {
7883       // This is implicit default-initialization of a const member in
7884       // a constructor. Complain that it needs to be explicitly
7885       // initialized.
7886       CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(S.CurContext);
7887       S.Diag(Kind.getLocation(), diag::err_uninitialized_member_in_ctor)
7888         << (Constructor->getInheritedConstructor() ? 2 :
7889             Constructor->isImplicit() ? 1 : 0)
7890         << S.Context.getTypeDeclType(Constructor->getParent())
7891         << /*const=*/1
7892         << Entity.getName();
7893       S.Diag(Entity.getDecl()->getLocation(), diag::note_previous_decl)
7894         << Entity.getName();
7895     } else {
7896       S.Diag(Kind.getLocation(), diag::err_default_init_const)
7897           << DestType << (bool)DestType->getAs<RecordType>();
7898     }
7899     break;
7900
7901   case FK_Incomplete:
7902     S.RequireCompleteType(Kind.getLocation(), FailedIncompleteType,
7903                           diag::err_init_incomplete_type);
7904     break;
7905
7906   case FK_ListInitializationFailed: {
7907     // Run the init list checker again to emit diagnostics.
7908     InitListExpr *InitList = cast<InitListExpr>(Args[0]);
7909     diagnoseListInit(S, Entity, InitList);
7910     break;
7911   }
7912
7913   case FK_PlaceholderType: {
7914     // FIXME: Already diagnosed!
7915     break;
7916   }
7917
7918   case FK_ExplicitConstructor: {
7919     S.Diag(Kind.getLocation(), diag::err_selected_explicit_constructor)
7920       << Args[0]->getSourceRange();
7921     OverloadCandidateSet::iterator Best;
7922     OverloadingResult Ovl
7923       = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
7924     (void)Ovl;
7925     assert(Ovl == OR_Success && "Inconsistent overload resolution");
7926     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
7927     S.Diag(CtorDecl->getLocation(),
7928            diag::note_explicit_ctor_deduction_guide_here) << false;
7929     break;
7930   }
7931   }
7932
7933   PrintInitLocationNote(S, Entity);
7934   return true;
7935 }
7936
7937 void InitializationSequence::dump(raw_ostream &OS) const {
7938   switch (SequenceKind) {
7939   case FailedSequence: {
7940     OS << "Failed sequence: ";
7941     switch (Failure) {
7942     case FK_TooManyInitsForReference:
7943       OS << "too many initializers for reference";
7944       break;
7945
7946     case FK_ParenthesizedListInitForReference:
7947       OS << "parenthesized list init for reference";
7948       break;
7949
7950     case FK_ArrayNeedsInitList:
7951       OS << "array requires initializer list";
7952       break;
7953
7954     case FK_AddressOfUnaddressableFunction:
7955       OS << "address of unaddressable function was taken";
7956       break;
7957
7958     case FK_ArrayNeedsInitListOrStringLiteral:
7959       OS << "array requires initializer list or string literal";
7960       break;
7961
7962     case FK_ArrayNeedsInitListOrWideStringLiteral:
7963       OS << "array requires initializer list or wide string literal";
7964       break;
7965
7966     case FK_NarrowStringIntoWideCharArray:
7967       OS << "narrow string into wide char array";
7968       break;
7969
7970     case FK_WideStringIntoCharArray:
7971       OS << "wide string into char array";
7972       break;
7973
7974     case FK_IncompatWideStringIntoWideChar:
7975       OS << "incompatible wide string into wide char array";
7976       break;
7977
7978     case FK_ArrayTypeMismatch:
7979       OS << "array type mismatch";
7980       break;
7981
7982     case FK_NonConstantArrayInit:
7983       OS << "non-constant array initializer";
7984       break;
7985
7986     case FK_AddressOfOverloadFailed:
7987       OS << "address of overloaded function failed";
7988       break;
7989
7990     case FK_ReferenceInitOverloadFailed:
7991       OS << "overload resolution for reference initialization failed";
7992       break;
7993
7994     case FK_NonConstLValueReferenceBindingToTemporary:
7995       OS << "non-const lvalue reference bound to temporary";
7996       break;
7997
7998     case FK_NonConstLValueReferenceBindingToBitfield:
7999       OS << "non-const lvalue reference bound to bit-field";
8000       break;
8001
8002     case FK_NonConstLValueReferenceBindingToVectorElement:
8003       OS << "non-const lvalue reference bound to vector element";
8004       break;
8005
8006     case FK_NonConstLValueReferenceBindingToUnrelated:
8007       OS << "non-const lvalue reference bound to unrelated type";
8008       break;
8009
8010     case FK_RValueReferenceBindingToLValue:
8011       OS << "rvalue reference bound to an lvalue";
8012       break;
8013
8014     case FK_ReferenceInitDropsQualifiers:
8015       OS << "reference initialization drops qualifiers";
8016       break;
8017
8018     case FK_ReferenceInitFailed:
8019       OS << "reference initialization failed";
8020       break;
8021
8022     case FK_ConversionFailed:
8023       OS << "conversion failed";
8024       break;
8025
8026     case FK_ConversionFromPropertyFailed:
8027       OS << "conversion from property failed";
8028       break;
8029
8030     case FK_TooManyInitsForScalar:
8031       OS << "too many initializers for scalar";
8032       break;
8033
8034     case FK_ParenthesizedListInitForScalar:
8035       OS << "parenthesized list init for reference";
8036       break;
8037
8038     case FK_ReferenceBindingToInitList:
8039       OS << "referencing binding to initializer list";
8040       break;
8041
8042     case FK_InitListBadDestinationType:
8043       OS << "initializer list for non-aggregate, non-scalar type";
8044       break;
8045
8046     case FK_UserConversionOverloadFailed:
8047       OS << "overloading failed for user-defined conversion";
8048       break;
8049
8050     case FK_ConstructorOverloadFailed:
8051       OS << "constructor overloading failed";
8052       break;
8053
8054     case FK_DefaultInitOfConst:
8055       OS << "default initialization of a const variable";
8056       break;
8057
8058     case FK_Incomplete:
8059       OS << "initialization of incomplete type";
8060       break;
8061
8062     case FK_ListInitializationFailed:
8063       OS << "list initialization checker failure";
8064       break;
8065
8066     case FK_VariableLengthArrayHasInitializer:
8067       OS << "variable length array has an initializer";
8068       break;
8069
8070     case FK_PlaceholderType:
8071       OS << "initializer expression isn't contextually valid";
8072       break;
8073
8074     case FK_ListConstructorOverloadFailed:
8075       OS << "list constructor overloading failed";
8076       break;
8077
8078     case FK_ExplicitConstructor:
8079       OS << "list copy initialization chose explicit constructor";
8080       break;
8081     }
8082     OS << '\n';
8083     return;
8084   }
8085
8086   case DependentSequence:
8087     OS << "Dependent sequence\n";
8088     return;
8089
8090   case NormalSequence:
8091     OS << "Normal sequence: ";
8092     break;
8093   }
8094
8095   for (step_iterator S = step_begin(), SEnd = step_end(); S != SEnd; ++S) {
8096     if (S != step_begin()) {
8097       OS << " -> ";
8098     }
8099
8100     switch (S->Kind) {
8101     case SK_ResolveAddressOfOverloadedFunction:
8102       OS << "resolve address of overloaded function";
8103       break;
8104
8105     case SK_CastDerivedToBaseRValue:
8106       OS << "derived-to-base (rvalue)";
8107       break;
8108
8109     case SK_CastDerivedToBaseXValue:
8110       OS << "derived-to-base (xvalue)";
8111       break;
8112
8113     case SK_CastDerivedToBaseLValue:
8114       OS << "derived-to-base (lvalue)";
8115       break;
8116
8117     case SK_BindReference:
8118       OS << "bind reference to lvalue";
8119       break;
8120
8121     case SK_BindReferenceToTemporary:
8122       OS << "bind reference to a temporary";
8123       break;
8124
8125     case SK_FinalCopy:
8126       OS << "final copy in class direct-initialization";
8127       break;
8128
8129     case SK_ExtraneousCopyToTemporary:
8130       OS << "extraneous C++03 copy to temporary";
8131       break;
8132
8133     case SK_UserConversion:
8134       OS << "user-defined conversion via " << *S->Function.Function;
8135       break;
8136
8137     case SK_QualificationConversionRValue:
8138       OS << "qualification conversion (rvalue)";
8139       break;
8140
8141     case SK_QualificationConversionXValue:
8142       OS << "qualification conversion (xvalue)";
8143       break;
8144
8145     case SK_QualificationConversionLValue:
8146       OS << "qualification conversion (lvalue)";
8147       break;
8148
8149     case SK_AtomicConversion:
8150       OS << "non-atomic-to-atomic conversion";
8151       break;
8152
8153     case SK_LValueToRValue:
8154       OS << "load (lvalue to rvalue)";
8155       break;
8156
8157     case SK_ConversionSequence:
8158       OS << "implicit conversion sequence (";
8159       S->ICS->dump(); // FIXME: use OS
8160       OS << ")";
8161       break;
8162
8163     case SK_ConversionSequenceNoNarrowing:
8164       OS << "implicit conversion sequence with narrowing prohibited (";
8165       S->ICS->dump(); // FIXME: use OS
8166       OS << ")";
8167       break;
8168
8169     case SK_ListInitialization:
8170       OS << "list aggregate initialization";
8171       break;
8172
8173     case SK_UnwrapInitList:
8174       OS << "unwrap reference initializer list";
8175       break;
8176
8177     case SK_RewrapInitList:
8178       OS << "rewrap reference initializer list";
8179       break;
8180
8181     case SK_ConstructorInitialization:
8182       OS << "constructor initialization";
8183       break;
8184
8185     case SK_ConstructorInitializationFromList:
8186       OS << "list initialization via constructor";
8187       break;
8188
8189     case SK_ZeroInitialization:
8190       OS << "zero initialization";
8191       break;
8192
8193     case SK_CAssignment:
8194       OS << "C assignment";
8195       break;
8196
8197     case SK_StringInit:
8198       OS << "string initialization";
8199       break;
8200
8201     case SK_ObjCObjectConversion:
8202       OS << "Objective-C object conversion";
8203       break;
8204
8205     case SK_ArrayLoopIndex:
8206       OS << "indexing for array initialization loop";
8207       break;
8208
8209     case SK_ArrayLoopInit:
8210       OS << "array initialization loop";
8211       break;
8212
8213     case SK_ArrayInit:
8214       OS << "array initialization";
8215       break;
8216
8217     case SK_GNUArrayInit:
8218       OS << "array initialization (GNU extension)";
8219       break;
8220
8221     case SK_ParenthesizedArrayInit:
8222       OS << "parenthesized array initialization";
8223       break;
8224
8225     case SK_PassByIndirectCopyRestore:
8226       OS << "pass by indirect copy and restore";
8227       break;
8228
8229     case SK_PassByIndirectRestore:
8230       OS << "pass by indirect restore";
8231       break;
8232
8233     case SK_ProduceObjCObject:
8234       OS << "Objective-C object retension";
8235       break;
8236
8237     case SK_StdInitializerList:
8238       OS << "std::initializer_list from initializer list";
8239       break;
8240
8241     case SK_StdInitializerListConstructorCall:
8242       OS << "list initialization from std::initializer_list";
8243       break;
8244
8245     case SK_OCLSamplerInit:
8246       OS << "OpenCL sampler_t from integer constant";
8247       break;
8248
8249     case SK_OCLZeroEvent:
8250       OS << "OpenCL event_t from zero";
8251       break;
8252
8253     case SK_OCLZeroQueue:
8254       OS << "OpenCL queue_t from zero";
8255       break;
8256     }
8257
8258     OS << " [" << S->Type.getAsString() << ']';
8259   }
8260
8261   OS << '\n';
8262 }
8263
8264 void InitializationSequence::dump() const {
8265   dump(llvm::errs());
8266 }
8267
8268 static void DiagnoseNarrowingInInitList(Sema &S,
8269                                         const ImplicitConversionSequence &ICS,
8270                                         QualType PreNarrowingType,
8271                                         QualType EntityType,
8272                                         const Expr *PostInit) {
8273   const StandardConversionSequence *SCS = nullptr;
8274   switch (ICS.getKind()) {
8275   case ImplicitConversionSequence::StandardConversion:
8276     SCS = &ICS.Standard;
8277     break;
8278   case ImplicitConversionSequence::UserDefinedConversion:
8279     SCS = &ICS.UserDefined.After;
8280     break;
8281   case ImplicitConversionSequence::AmbiguousConversion:
8282   case ImplicitConversionSequence::EllipsisConversion:
8283   case ImplicitConversionSequence::BadConversion:
8284     return;
8285   }
8286
8287   // C++11 [dcl.init.list]p7: Check whether this is a narrowing conversion.
8288   APValue ConstantValue;
8289   QualType ConstantType;
8290   switch (SCS->getNarrowingKind(S.Context, PostInit, ConstantValue,
8291                                 ConstantType)) {
8292   case NK_Not_Narrowing:
8293   case NK_Dependent_Narrowing:
8294     // No narrowing occurred.
8295     return;
8296
8297   case NK_Type_Narrowing:
8298     // This was a floating-to-integer conversion, which is always considered a
8299     // narrowing conversion even if the value is a constant and can be
8300     // represented exactly as an integer.
8301     S.Diag(PostInit->getLocStart(),
8302            (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
8303                ? diag::warn_init_list_type_narrowing
8304                : diag::ext_init_list_type_narrowing)
8305       << PostInit->getSourceRange()
8306       << PreNarrowingType.getLocalUnqualifiedType()
8307       << EntityType.getLocalUnqualifiedType();
8308     break;
8309
8310   case NK_Constant_Narrowing:
8311     // A constant value was narrowed.
8312     S.Diag(PostInit->getLocStart(),
8313            (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
8314                ? diag::warn_init_list_constant_narrowing
8315                : diag::ext_init_list_constant_narrowing)
8316       << PostInit->getSourceRange()
8317       << ConstantValue.getAsString(S.getASTContext(), ConstantType)
8318       << EntityType.getLocalUnqualifiedType();
8319     break;
8320
8321   case NK_Variable_Narrowing:
8322     // A variable's value may have been narrowed.
8323     S.Diag(PostInit->getLocStart(),
8324            (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
8325                ? diag::warn_init_list_variable_narrowing
8326                : diag::ext_init_list_variable_narrowing)
8327       << PostInit->getSourceRange()
8328       << PreNarrowingType.getLocalUnqualifiedType()
8329       << EntityType.getLocalUnqualifiedType();
8330     break;
8331   }
8332
8333   SmallString<128> StaticCast;
8334   llvm::raw_svector_ostream OS(StaticCast);
8335   OS << "static_cast<";
8336   if (const TypedefType *TT = EntityType->getAs<TypedefType>()) {
8337     // It's important to use the typedef's name if there is one so that the
8338     // fixit doesn't break code using types like int64_t.
8339     //
8340     // FIXME: This will break if the typedef requires qualification.  But
8341     // getQualifiedNameAsString() includes non-machine-parsable components.
8342     OS << *TT->getDecl();
8343   } else if (const BuiltinType *BT = EntityType->getAs<BuiltinType>())
8344     OS << BT->getName(S.getLangOpts());
8345   else {
8346     // Oops, we didn't find the actual type of the variable.  Don't emit a fixit
8347     // with a broken cast.
8348     return;
8349   }
8350   OS << ">(";
8351   S.Diag(PostInit->getLocStart(), diag::note_init_list_narrowing_silence)
8352       << PostInit->getSourceRange()
8353       << FixItHint::CreateInsertion(PostInit->getLocStart(), OS.str())
8354       << FixItHint::CreateInsertion(
8355              S.getLocForEndOfToken(PostInit->getLocEnd()), ")");
8356 }
8357
8358 //===----------------------------------------------------------------------===//
8359 // Initialization helper functions
8360 //===----------------------------------------------------------------------===//
8361 bool
8362 Sema::CanPerformCopyInitialization(const InitializedEntity &Entity,
8363                                    ExprResult Init) {
8364   if (Init.isInvalid())
8365     return false;
8366
8367   Expr *InitE = Init.get();
8368   assert(InitE && "No initialization expression");
8369
8370   InitializationKind Kind
8371     = InitializationKind::CreateCopy(InitE->getLocStart(), SourceLocation());
8372   InitializationSequence Seq(*this, Entity, Kind, InitE);
8373   return !Seq.Failed();
8374 }
8375
8376 ExprResult
8377 Sema::PerformCopyInitialization(const InitializedEntity &Entity,
8378                                 SourceLocation EqualLoc,
8379                                 ExprResult Init,
8380                                 bool TopLevelOfInitList,
8381                                 bool AllowExplicit) {
8382   if (Init.isInvalid())
8383     return ExprError();
8384
8385   Expr *InitE = Init.get();
8386   assert(InitE && "No initialization expression?");
8387
8388   if (EqualLoc.isInvalid())
8389     EqualLoc = InitE->getLocStart();
8390
8391   InitializationKind Kind = InitializationKind::CreateCopy(InitE->getLocStart(),
8392                                                            EqualLoc,
8393                                                            AllowExplicit);
8394   InitializationSequence Seq(*this, Entity, Kind, InitE, TopLevelOfInitList);
8395
8396   // Prevent infinite recursion when performing parameter copy-initialization.
8397   const bool ShouldTrackCopy =
8398       Entity.isParameterKind() && Seq.isConstructorInitialization();
8399   if (ShouldTrackCopy) {
8400     if (llvm::find(CurrentParameterCopyTypes, Entity.getType()) !=
8401         CurrentParameterCopyTypes.end()) {
8402       Seq.SetOverloadFailure(
8403           InitializationSequence::FK_ConstructorOverloadFailed,
8404           OR_No_Viable_Function);
8405
8406       // Try to give a meaningful diagnostic note for the problematic
8407       // constructor.
8408       const auto LastStep = Seq.step_end() - 1;
8409       assert(LastStep->Kind ==
8410              InitializationSequence::SK_ConstructorInitialization);
8411       const FunctionDecl *Function = LastStep->Function.Function;
8412       auto Candidate =
8413           llvm::find_if(Seq.getFailedCandidateSet(),
8414                         [Function](const OverloadCandidate &Candidate) -> bool {
8415                           return Candidate.Viable &&
8416                                  Candidate.Function == Function &&
8417                                  Candidate.Conversions.size() > 0;
8418                         });
8419       if (Candidate != Seq.getFailedCandidateSet().end() &&
8420           Function->getNumParams() > 0) {
8421         Candidate->Viable = false;
8422         Candidate->FailureKind = ovl_fail_bad_conversion;
8423         Candidate->Conversions[0].setBad(BadConversionSequence::no_conversion,
8424                                          InitE,
8425                                          Function->getParamDecl(0)->getType());
8426       }
8427     }
8428     CurrentParameterCopyTypes.push_back(Entity.getType());
8429   }
8430
8431   ExprResult Result = Seq.Perform(*this, Entity, Kind, InitE);
8432
8433   if (ShouldTrackCopy)
8434     CurrentParameterCopyTypes.pop_back();
8435
8436   return Result;
8437 }
8438
8439 /// Determine whether RD is, or is derived from, a specialization of CTD.
8440 static bool isOrIsDerivedFromSpecializationOf(CXXRecordDecl *RD,
8441                                               ClassTemplateDecl *CTD) {
8442   auto NotSpecialization = [&] (const CXXRecordDecl *Candidate) {
8443     auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(Candidate);
8444     return !CTSD || !declaresSameEntity(CTSD->getSpecializedTemplate(), CTD);
8445   };
8446   return !(NotSpecialization(RD) && RD->forallBases(NotSpecialization));
8447 }
8448
8449 QualType Sema::DeduceTemplateSpecializationFromInitializer(
8450     TypeSourceInfo *TSInfo, const InitializedEntity &Entity,
8451     const InitializationKind &Kind, MultiExprArg Inits) {
8452   auto *DeducedTST = dyn_cast<DeducedTemplateSpecializationType>(
8453       TSInfo->getType()->getContainedDeducedType());
8454   assert(DeducedTST && "not a deduced template specialization type");
8455
8456   // We can only perform deduction for class templates.
8457   auto TemplateName = DeducedTST->getTemplateName();
8458   auto *Template =
8459       dyn_cast_or_null<ClassTemplateDecl>(TemplateName.getAsTemplateDecl());
8460   if (!Template) {
8461     Diag(Kind.getLocation(),
8462          diag::err_deduced_non_class_template_specialization_type)
8463       << (int)getTemplateNameKindForDiagnostics(TemplateName) << TemplateName;
8464     if (auto *TD = TemplateName.getAsTemplateDecl())
8465       Diag(TD->getLocation(), diag::note_template_decl_here);
8466     return QualType();
8467   }
8468
8469   // Can't deduce from dependent arguments.
8470   if (Expr::hasAnyTypeDependentArguments(Inits))
8471     return Context.DependentTy;
8472
8473   // FIXME: Perform "exact type" matching first, per CWG discussion?
8474   //        Or implement this via an implied 'T(T) -> T' deduction guide?
8475
8476   // FIXME: Do we need/want a std::initializer_list<T> special case?
8477
8478   // Look up deduction guides, including those synthesized from constructors.
8479   //
8480   // C++1z [over.match.class.deduct]p1:
8481   //   A set of functions and function templates is formed comprising:
8482   //   - For each constructor of the class template designated by the
8483   //     template-name, a function template [...]
8484   //  - For each deduction-guide, a function or function template [...]
8485   DeclarationNameInfo NameInfo(
8486       Context.DeclarationNames.getCXXDeductionGuideName(Template),
8487       TSInfo->getTypeLoc().getEndLoc());
8488   LookupResult Guides(*this, NameInfo, LookupOrdinaryName);
8489   LookupQualifiedName(Guides, Template->getDeclContext());
8490
8491   // FIXME: Do not diagnose inaccessible deduction guides. The standard isn't
8492   // clear on this, but they're not found by name so access does not apply.
8493   Guides.suppressDiagnostics();
8494
8495   // Figure out if this is list-initialization.
8496   InitListExpr *ListInit =
8497       (Inits.size() == 1 && Kind.getKind() != InitializationKind::IK_Direct)
8498           ? dyn_cast<InitListExpr>(Inits[0])
8499           : nullptr;
8500
8501   // C++1z [over.match.class.deduct]p1:
8502   //   Initialization and overload resolution are performed as described in
8503   //   [dcl.init] and [over.match.ctor], [over.match.copy], or [over.match.list]
8504   //   (as appropriate for the type of initialization performed) for an object
8505   //   of a hypothetical class type, where the selected functions and function
8506   //   templates are considered to be the constructors of that class type
8507   //
8508   // Since we know we're initializing a class type of a type unrelated to that
8509   // of the initializer, this reduces to something fairly reasonable.
8510   OverloadCandidateSet Candidates(Kind.getLocation(),
8511                                   OverloadCandidateSet::CSK_Normal);
8512   OverloadCandidateSet::iterator Best;
8513   auto tryToResolveOverload =
8514       [&](bool OnlyListConstructors) -> OverloadingResult {
8515     Candidates.clear(OverloadCandidateSet::CSK_Normal);
8516     for (auto I = Guides.begin(), E = Guides.end(); I != E; ++I) {
8517       NamedDecl *D = (*I)->getUnderlyingDecl();
8518       if (D->isInvalidDecl())
8519         continue;
8520
8521       auto *TD = dyn_cast<FunctionTemplateDecl>(D);
8522       auto *GD = dyn_cast_or_null<CXXDeductionGuideDecl>(
8523           TD ? TD->getTemplatedDecl() : dyn_cast<FunctionDecl>(D));
8524       if (!GD)
8525         continue;
8526
8527       // C++ [over.match.ctor]p1: (non-list copy-initialization from non-class)
8528       //   For copy-initialization, the candidate functions are all the
8529       //   converting constructors (12.3.1) of that class.
8530       // C++ [over.match.copy]p1: (non-list copy-initialization from class)
8531       //   The converting constructors of T are candidate functions.
8532       if (Kind.isCopyInit() && !ListInit) {
8533         // Only consider converting constructors.
8534         if (GD->isExplicit())
8535           continue;
8536
8537         // When looking for a converting constructor, deduction guides that
8538         // could never be called with one argument are not interesting to
8539         // check or note.
8540         if (GD->getMinRequiredArguments() > 1 ||
8541             (GD->getNumParams() == 0 && !GD->isVariadic()))
8542           continue;
8543       }
8544
8545       // C++ [over.match.list]p1.1: (first phase list initialization)
8546       //   Initially, the candidate functions are the initializer-list
8547       //   constructors of the class T
8548       if (OnlyListConstructors && !isInitListConstructor(GD))
8549         continue;
8550
8551       // C++ [over.match.list]p1.2: (second phase list initialization)
8552       //   the candidate functions are all the constructors of the class T
8553       // C++ [over.match.ctor]p1: (all other cases)
8554       //   the candidate functions are all the constructors of the class of
8555       //   the object being initialized
8556
8557       // C++ [over.best.ics]p4:
8558       //   When [...] the constructor [...] is a candidate by
8559       //    - [over.match.copy] (in all cases)
8560       // FIXME: The "second phase of [over.match.list] case can also
8561       // theoretically happen here, but it's not clear whether we can
8562       // ever have a parameter of the right type.
8563       bool SuppressUserConversions = Kind.isCopyInit();
8564
8565       if (TD)
8566         AddTemplateOverloadCandidate(TD, I.getPair(), /*ExplicitArgs*/ nullptr,
8567                                      Inits, Candidates,
8568                                      SuppressUserConversions);
8569       else
8570         AddOverloadCandidate(GD, I.getPair(), Inits, Candidates,
8571                              SuppressUserConversions);
8572     }
8573     return Candidates.BestViableFunction(*this, Kind.getLocation(), Best);
8574   };
8575
8576   OverloadingResult Result = OR_No_Viable_Function;
8577
8578   // C++11 [over.match.list]p1, per DR1467: for list-initialization, first
8579   // try initializer-list constructors.
8580   if (ListInit) {
8581     bool TryListConstructors = true;
8582
8583     // Try list constructors unless the list is empty and the class has one or
8584     // more default constructors, in which case those constructors win.
8585     if (!ListInit->getNumInits()) {
8586       for (NamedDecl *D : Guides) {
8587         auto *FD = dyn_cast<FunctionDecl>(D->getUnderlyingDecl());
8588         if (FD && FD->getMinRequiredArguments() == 0) {
8589           TryListConstructors = false;
8590           break;
8591         }
8592       }
8593     } else if (ListInit->getNumInits() == 1) {
8594       // C++ [over.match.class.deduct]:
8595       //   As an exception, the first phase in [over.match.list] (considering
8596       //   initializer-list constructors) is omitted if the initializer list
8597       //   consists of a single expression of type cv U, where U is a
8598       //   specialization of C or a class derived from a specialization of C.
8599       Expr *E = ListInit->getInit(0);
8600       auto *RD = E->getType()->getAsCXXRecordDecl();
8601       if (!isa<InitListExpr>(E) && RD &&
8602           isOrIsDerivedFromSpecializationOf(RD, Template))
8603         TryListConstructors = false;
8604     }
8605
8606     if (TryListConstructors)
8607       Result = tryToResolveOverload(/*OnlyListConstructor*/true);
8608     // Then unwrap the initializer list and try again considering all
8609     // constructors.
8610     Inits = MultiExprArg(ListInit->getInits(), ListInit->getNumInits());
8611   }
8612
8613   // If list-initialization fails, or if we're doing any other kind of
8614   // initialization, we (eventually) consider constructors.
8615   if (Result == OR_No_Viable_Function)
8616     Result = tryToResolveOverload(/*OnlyListConstructor*/false);
8617
8618   switch (Result) {
8619   case OR_Ambiguous:
8620     Diag(Kind.getLocation(), diag::err_deduced_class_template_ctor_ambiguous)
8621       << TemplateName;
8622     // FIXME: For list-initialization candidates, it'd usually be better to
8623     // list why they were not viable when given the initializer list itself as
8624     // an argument.
8625     Candidates.NoteCandidates(*this, OCD_ViableCandidates, Inits);
8626     return QualType();
8627
8628   case OR_No_Viable_Function: {
8629     CXXRecordDecl *Primary =
8630         cast<ClassTemplateDecl>(Template)->getTemplatedDecl();
8631     bool Complete =
8632         isCompleteType(Kind.getLocation(), Context.getTypeDeclType(Primary));
8633     Diag(Kind.getLocation(),
8634          Complete ? diag::err_deduced_class_template_ctor_no_viable
8635                   : diag::err_deduced_class_template_incomplete)
8636       << TemplateName << !Guides.empty();
8637     Candidates.NoteCandidates(*this, OCD_AllCandidates, Inits);
8638     return QualType();
8639   }
8640
8641   case OR_Deleted: {
8642     Diag(Kind.getLocation(), diag::err_deduced_class_template_deleted)
8643       << TemplateName;
8644     NoteDeletedFunction(Best->Function);
8645     return QualType();
8646   }
8647
8648   case OR_Success:
8649     // C++ [over.match.list]p1:
8650     //   In copy-list-initialization, if an explicit constructor is chosen, the
8651     //   initialization is ill-formed.
8652     if (Kind.isCopyInit() && ListInit &&
8653         cast<CXXDeductionGuideDecl>(Best->Function)->isExplicit()) {
8654       bool IsDeductionGuide = !Best->Function->isImplicit();
8655       Diag(Kind.getLocation(), diag::err_deduced_class_template_explicit)
8656           << TemplateName << IsDeductionGuide;
8657       Diag(Best->Function->getLocation(),
8658            diag::note_explicit_ctor_deduction_guide_here)
8659           << IsDeductionGuide;
8660       return QualType();
8661     }
8662
8663     // Make sure we didn't select an unusable deduction guide, and mark it
8664     // as referenced.
8665     DiagnoseUseOfDecl(Best->Function, Kind.getLocation());
8666     MarkFunctionReferenced(Kind.getLocation(), Best->Function);
8667     break;
8668   }
8669
8670   // C++ [dcl.type.class.deduct]p1:
8671   //  The placeholder is replaced by the return type of the function selected
8672   //  by overload resolution for class template deduction.
8673   return SubstAutoType(TSInfo->getType(), Best->Function->getReturnType());
8674 }