1 //===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements semantic analysis for cast expressions, including
11 // 1) C-style casts like '(int) x'
12 // 2) C++ functional casts like 'int(x)'
13 // 3) C++ named casts like 'static_cast<int>(x)'
15 //===----------------------------------------------------------------------===//
17 #include "clang/Sema/SemaInternal.h"
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/CXXInheritance.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/ExprObjC.h"
22 #include "clang/AST/RecordLayout.h"
23 #include "clang/Basic/PartialDiagnostic.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/Initialization.h"
26 #include "llvm/ADT/SmallVector.h"
28 using namespace clang;
33 TC_NotApplicable, ///< The cast method is not applicable.
34 TC_Success, ///< The cast method is appropriate and successful.
35 TC_Failed ///< The cast method is appropriate, but failed. A
36 ///< diagnostic has been emitted.
40 CT_Const, ///< const_cast
41 CT_Static, ///< static_cast
42 CT_Reinterpret, ///< reinterpret_cast
43 CT_Dynamic, ///< dynamic_cast
44 CT_CStyle, ///< (Type)expr
45 CT_Functional ///< Type(expr)
49 struct CastOperation {
50 CastOperation(Sema &S, QualType destType, ExprResult src)
51 : Self(S), SrcExpr(src), DestType(destType),
52 ResultType(destType.getNonLValueExprType(S.Context)),
53 ValueKind(Expr::getValueKindForType(destType)),
54 Kind(CK_Dependent), IsARCUnbridgedCast(false) {
56 if (const BuiltinType *placeholder =
57 src.get()->getType()->getAsPlaceholderType()) {
58 PlaceholderKind = placeholder->getKind();
60 PlaceholderKind = (BuiltinType::Kind) 0;
68 ExprValueKind ValueKind;
70 BuiltinType::Kind PlaceholderKind;
72 bool IsARCUnbridgedCast;
75 SourceRange DestRange;
77 // Top-level semantics-checking routines.
78 void CheckConstCast();
79 void CheckReinterpretCast();
80 void CheckStaticCast();
81 void CheckDynamicCast();
82 void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
83 void CheckCStyleCast();
85 /// Complete an apparently-successful cast operation that yields
86 /// the given expression.
87 ExprResult complete(CastExpr *castExpr) {
88 // If this is an unbridged cast, wrap the result in an implicit
89 // cast that yields the unbridged-cast placeholder type.
90 if (IsARCUnbridgedCast) {
91 castExpr = ImplicitCastExpr::Create(Self.Context,
92 Self.Context.ARCUnbridgedCastTy,
93 CK_Dependent, castExpr, nullptr,
94 castExpr->getValueKind());
99 // Internal convenience methods.
101 /// Try to handle the given placeholder expression kind. Return
102 /// true if the source expression has the appropriate placeholder
103 /// kind. A placeholder can only be claimed once.
104 bool claimPlaceholder(BuiltinType::Kind K) {
105 if (PlaceholderKind != K) return false;
107 PlaceholderKind = (BuiltinType::Kind) 0;
111 bool isPlaceholder() const {
112 return PlaceholderKind != 0;
114 bool isPlaceholder(BuiltinType::Kind K) const {
115 return PlaceholderKind == K;
118 void checkCastAlign() {
119 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
122 void checkObjCARCConversion(Sema::CheckedConversionKind CCK) {
123 assert(Self.getLangOpts().ObjCAutoRefCount);
125 Expr *src = SrcExpr.get();
126 if (Self.CheckObjCARCConversion(OpRange, DestType, src, CCK) ==
128 IsARCUnbridgedCast = true;
132 /// Check for and handle non-overload placeholder expressions.
133 void checkNonOverloadPlaceholders() {
134 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
137 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
138 if (SrcExpr.isInvalid())
140 PlaceholderKind = (BuiltinType::Kind) 0;
145 // The Try functions attempt a specific way of casting. If they succeed, they
146 // return TC_Success. If their way of casting is not appropriate for the given
147 // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
148 // to emit if no other way succeeds. If their way of casting is appropriate but
149 // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
150 // they emit a specialized diagnostic.
151 // All diagnostics returned by these functions must expect the same three
153 // %0: Cast Type (a value from the CastType enumeration)
155 // %2: Destination Type
156 static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
157 QualType DestType, bool CStyle,
159 CXXCastPath &BasePath,
161 static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
162 QualType DestType, bool CStyle,
163 const SourceRange &OpRange,
166 CXXCastPath &BasePath);
167 static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
168 QualType DestType, bool CStyle,
169 const SourceRange &OpRange,
172 CXXCastPath &BasePath);
173 static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
174 CanQualType DestType, bool CStyle,
175 const SourceRange &OpRange,
176 QualType OrigSrcType,
177 QualType OrigDestType, unsigned &msg,
179 CXXCastPath &BasePath);
180 static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
182 QualType DestType,bool CStyle,
183 const SourceRange &OpRange,
186 CXXCastPath &BasePath);
188 static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
190 Sema::CheckedConversionKind CCK,
191 const SourceRange &OpRange,
192 unsigned &msg, CastKind &Kind,
193 bool ListInitialization);
194 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
196 Sema::CheckedConversionKind CCK,
197 const SourceRange &OpRange,
198 unsigned &msg, CastKind &Kind,
199 CXXCastPath &BasePath,
200 bool ListInitialization);
201 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
202 QualType DestType, bool CStyle,
204 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
205 QualType DestType, bool CStyle,
206 const SourceRange &OpRange,
211 /// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
213 Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
214 SourceLocation LAngleBracketLoc, Declarator &D,
215 SourceLocation RAngleBracketLoc,
216 SourceLocation LParenLoc, Expr *E,
217 SourceLocation RParenLoc) {
219 assert(!D.isInvalidType());
221 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
222 if (D.isInvalidType())
225 if (getLangOpts().CPlusPlus) {
226 // Check that there are no default arguments (C++ only).
227 CheckExtraCXXDefaultArguments(D);
230 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
231 SourceRange(LAngleBracketLoc, RAngleBracketLoc),
232 SourceRange(LParenLoc, RParenLoc));
236 Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
237 TypeSourceInfo *DestTInfo, Expr *E,
238 SourceRange AngleBrackets, SourceRange Parens) {
240 QualType DestType = DestTInfo->getType();
242 // If the type is dependent, we won't do the semantic analysis now.
244 DestType->isDependentType() || Ex.get()->isTypeDependent();
246 CastOperation Op(*this, DestType, E);
247 Op.OpRange = SourceRange(OpLoc, Parens.getEnd());
248 Op.DestRange = AngleBrackets;
251 default: llvm_unreachable("Unknown C++ cast!");
253 case tok::kw_const_cast:
254 if (!TypeDependent) {
256 if (Op.SrcExpr.isInvalid())
259 return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
260 Op.ValueKind, Op.SrcExpr.get(), DestTInfo,
261 OpLoc, Parens.getEnd(),
264 case tok::kw_dynamic_cast: {
265 if (!TypeDependent) {
266 Op.CheckDynamicCast();
267 if (Op.SrcExpr.isInvalid())
270 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
271 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
272 &Op.BasePath, DestTInfo,
273 OpLoc, Parens.getEnd(),
276 case tok::kw_reinterpret_cast: {
277 if (!TypeDependent) {
278 Op.CheckReinterpretCast();
279 if (Op.SrcExpr.isInvalid())
282 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
283 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
284 nullptr, DestTInfo, OpLoc,
288 case tok::kw_static_cast: {
289 if (!TypeDependent) {
290 Op.CheckStaticCast();
291 if (Op.SrcExpr.isInvalid())
295 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
296 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
297 &Op.BasePath, DestTInfo,
298 OpLoc, Parens.getEnd(),
304 /// Try to diagnose a failed overloaded cast. Returns true if
305 /// diagnostics were emitted.
306 static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
307 SourceRange range, Expr *src,
309 bool listInitialization) {
311 // These cast kinds don't consider user-defined conversions.
324 QualType srcType = src->getType();
325 if (!destType->isRecordType() && !srcType->isRecordType())
328 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
329 InitializationKind initKind
330 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
331 range, listInitialization)
332 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
334 : InitializationKind::CreateCast(/*type range?*/ range);
335 InitializationSequence sequence(S, entity, initKind, src);
337 assert(sequence.Failed() && "initialization succeeded on second try?");
338 switch (sequence.getFailureKind()) {
339 default: return false;
341 case InitializationSequence::FK_ConstructorOverloadFailed:
342 case InitializationSequence::FK_UserConversionOverloadFailed:
346 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
349 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
351 switch (sequence.getFailedOverloadResult()) {
352 case OR_Success: llvm_unreachable("successful failed overload");
353 case OR_No_Viable_Function:
354 if (candidates.empty())
355 msg = diag::err_ovl_no_conversion_in_cast;
357 msg = diag::err_ovl_no_viable_conversion_in_cast;
358 howManyCandidates = OCD_AllCandidates;
362 msg = diag::err_ovl_ambiguous_conversion_in_cast;
363 howManyCandidates = OCD_ViableCandidates;
367 msg = diag::err_ovl_deleted_conversion_in_cast;
368 howManyCandidates = OCD_ViableCandidates;
372 S.Diag(range.getBegin(), msg)
373 << CT << srcType << destType
374 << range << src->getSourceRange();
376 candidates.NoteCandidates(S, howManyCandidates, src);
381 /// Diagnose a failed cast.
382 static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
383 SourceRange opRange, Expr *src, QualType destType,
384 bool listInitialization) {
385 if (msg == diag::err_bad_cxx_cast_generic &&
386 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
390 S.Diag(opRange.getBegin(), msg) << castType
391 << src->getType() << destType << opRange << src->getSourceRange();
393 // Detect if both types are (ptr to) class, and note any incompleteness.
394 int DifferentPtrness = 0;
395 QualType From = destType;
396 if (auto Ptr = From->getAs<PointerType>()) {
397 From = Ptr->getPointeeType();
400 QualType To = src->getType();
401 if (auto Ptr = To->getAs<PointerType>()) {
402 To = Ptr->getPointeeType();
405 if (!DifferentPtrness) {
406 auto RecFrom = From->getAs<RecordType>();
407 auto RecTo = To->getAs<RecordType>();
408 if (RecFrom && RecTo) {
409 auto DeclFrom = RecFrom->getAsCXXRecordDecl();
410 if (!DeclFrom->isCompleteDefinition())
411 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete)
412 << DeclFrom->getDeclName();
413 auto DeclTo = RecTo->getAsCXXRecordDecl();
414 if (!DeclTo->isCompleteDefinition())
415 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete)
416 << DeclTo->getDeclName();
421 /// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes,
422 /// this removes one level of indirection from both types, provided that they're
423 /// the same kind of pointer (plain or to-member). Unlike the Sema function,
424 /// this one doesn't care if the two pointers-to-member don't point into the
425 /// same class. This is because CastsAwayConstness doesn't care.
426 static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
427 const PointerType *T1PtrType = T1->getAs<PointerType>(),
428 *T2PtrType = T2->getAs<PointerType>();
429 if (T1PtrType && T2PtrType) {
430 T1 = T1PtrType->getPointeeType();
431 T2 = T2PtrType->getPointeeType();
434 const ObjCObjectPointerType *T1ObjCPtrType =
435 T1->getAs<ObjCObjectPointerType>(),
437 T2->getAs<ObjCObjectPointerType>();
440 T1 = T1ObjCPtrType->getPointeeType();
441 T2 = T2ObjCPtrType->getPointeeType();
444 else if (T2PtrType) {
445 T1 = T1ObjCPtrType->getPointeeType();
446 T2 = T2PtrType->getPointeeType();
450 else if (T2ObjCPtrType) {
452 T2 = T2ObjCPtrType->getPointeeType();
453 T1 = T1PtrType->getPointeeType();
458 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(),
459 *T2MPType = T2->getAs<MemberPointerType>();
460 if (T1MPType && T2MPType) {
461 T1 = T1MPType->getPointeeType();
462 T2 = T2MPType->getPointeeType();
466 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(),
467 *T2BPType = T2->getAs<BlockPointerType>();
468 if (T1BPType && T2BPType) {
469 T1 = T1BPType->getPointeeType();
470 T2 = T2BPType->getPointeeType();
477 /// CastsAwayConstness - Check if the pointer conversion from SrcType to
478 /// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by
479 /// the cast checkers. Both arguments must denote pointer (possibly to member)
482 /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
484 /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
486 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
487 bool CheckCVR, bool CheckObjCLifetime,
488 QualType *TheOffendingSrcType = nullptr,
489 QualType *TheOffendingDestType = nullptr,
490 Qualifiers *CastAwayQualifiers = nullptr) {
491 // If the only checking we care about is for Objective-C lifetime qualifiers,
492 // and we're not in ARC mode, there's nothing to check.
493 if (!CheckCVR && CheckObjCLifetime &&
494 !Self.Context.getLangOpts().ObjCAutoRefCount)
497 // Casting away constness is defined in C++ 5.2.11p8 with reference to
498 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since
499 // the rules are non-trivial. So first we construct Tcv *...cv* as described
501 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
502 SrcType->isBlockPointerType()) &&
503 "Source type is not pointer or pointer to member.");
504 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
505 DestType->isBlockPointerType()) &&
506 "Destination type is not pointer or pointer to member.");
508 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
509 UnwrappedDestType = Self.Context.getCanonicalType(DestType);
510 SmallVector<Qualifiers, 8> cv1, cv2;
512 // Find the qualifiers. We only care about cvr-qualifiers for the
513 // purpose of this check, because other qualifiers (address spaces,
514 // Objective-C GC, etc.) are part of the type's identity.
515 QualType PrevUnwrappedSrcType = UnwrappedSrcType;
516 QualType PrevUnwrappedDestType = UnwrappedDestType;
517 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) {
518 // Determine the relevant qualifiers at this level.
519 Qualifiers SrcQuals, DestQuals;
520 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
521 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
523 Qualifiers RetainedSrcQuals, RetainedDestQuals;
525 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers());
526 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers());
528 if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType &&
529 TheOffendingDestType && CastAwayQualifiers) {
530 *TheOffendingSrcType = PrevUnwrappedSrcType;
531 *TheOffendingDestType = PrevUnwrappedDestType;
532 *CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals;
536 if (CheckObjCLifetime &&
537 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
540 cv1.push_back(RetainedSrcQuals);
541 cv2.push_back(RetainedDestQuals);
543 PrevUnwrappedSrcType = UnwrappedSrcType;
544 PrevUnwrappedDestType = UnwrappedDestType;
549 // Construct void pointers with those qualifiers (in reverse order of
550 // unwrapping, of course).
551 QualType SrcConstruct = Self.Context.VoidTy;
552 QualType DestConstruct = Self.Context.VoidTy;
553 ASTContext &Context = Self.Context;
554 for (SmallVectorImpl<Qualifiers>::reverse_iterator i1 = cv1.rbegin(),
556 i1 != cv1.rend(); ++i1, ++i2) {
558 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1));
560 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2));
563 // Test if they're compatible.
564 bool ObjCLifetimeConversion;
565 return SrcConstruct != DestConstruct &&
566 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false,
567 ObjCLifetimeConversion);
570 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
571 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
572 /// checked downcasts in class hierarchies.
573 void CastOperation::CheckDynamicCast() {
574 if (ValueKind == VK_RValue)
575 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
576 else if (isPlaceholder())
577 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
578 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
581 QualType OrigSrcType = SrcExpr.get()->getType();
582 QualType DestType = Self.Context.getCanonicalType(this->DestType);
584 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
585 // or "pointer to cv void".
587 QualType DestPointee;
588 const PointerType *DestPointer = DestType->getAs<PointerType>();
589 const ReferenceType *DestReference = nullptr;
591 DestPointee = DestPointer->getPointeeType();
592 } else if ((DestReference = DestType->getAs<ReferenceType>())) {
593 DestPointee = DestReference->getPointeeType();
595 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
596 << this->DestType << DestRange;
597 SrcExpr = ExprError();
601 const RecordType *DestRecord = DestPointee->getAs<RecordType>();
602 if (DestPointee->isVoidType()) {
603 assert(DestPointer && "Reference to void is not possible");
604 } else if (DestRecord) {
605 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
606 diag::err_bad_dynamic_cast_incomplete,
608 SrcExpr = ExprError();
612 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
613 << DestPointee.getUnqualifiedType() << DestRange;
614 SrcExpr = ExprError();
618 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
619 // complete class type, [...]. If T is an lvalue reference type, v shall be
620 // an lvalue of a complete class type, [...]. If T is an rvalue reference
621 // type, v shall be an expression having a complete class type, [...]
622 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
625 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
626 SrcPointee = SrcPointer->getPointeeType();
628 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
629 << OrigSrcType << SrcExpr.get()->getSourceRange();
630 SrcExpr = ExprError();
633 } else if (DestReference->isLValueReferenceType()) {
634 if (!SrcExpr.get()->isLValue()) {
635 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
636 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
638 SrcPointee = SrcType;
640 // If we're dynamic_casting from a prvalue to an rvalue reference, we need
641 // to materialize the prvalue before we bind the reference to it.
642 if (SrcExpr.get()->isRValue())
643 SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
644 SrcType, SrcExpr.get(), /*IsLValueReference*/false);
645 SrcPointee = SrcType;
648 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
650 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
651 diag::err_bad_dynamic_cast_incomplete,
653 SrcExpr = ExprError();
657 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
658 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
659 SrcExpr = ExprError();
663 assert((DestPointer || DestReference) &&
664 "Bad destination non-ptr/ref slipped through.");
665 assert((DestRecord || DestPointee->isVoidType()) &&
666 "Bad destination pointee slipped through.");
667 assert(SrcRecord && "Bad source pointee slipped through.");
669 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
670 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
671 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
672 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
673 SrcExpr = ExprError();
677 // C++ 5.2.7p3: If the type of v is the same as the required result type,
679 if (DestRecord == SrcRecord) {
685 // Upcasts are resolved statically.
686 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) {
687 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
688 OpRange.getBegin(), OpRange,
690 SrcExpr = ExprError();
694 Kind = CK_DerivedToBase;
698 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
699 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
700 assert(SrcDecl && "Definition missing");
701 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
702 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
703 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
704 SrcExpr = ExprError();
707 // dynamic_cast is not available with -fno-rtti.
708 // As an exception, dynamic_cast to void* is available because it doesn't
710 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
711 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
712 SrcExpr = ExprError();
716 // Done. Everything else is run-time checks.
720 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
721 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
723 /// const char *str = "literal";
724 /// legacy_function(const_cast\<char*\>(str));
725 void CastOperation::CheckConstCast() {
726 if (ValueKind == VK_RValue)
727 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
728 else if (isPlaceholder())
729 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
730 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
733 unsigned msg = diag::err_bad_cxx_cast_generic;
734 if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success
736 Self.Diag(OpRange.getBegin(), msg) << CT_Const
737 << SrcExpr.get()->getType() << DestType << OpRange;
738 SrcExpr = ExprError();
742 /// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
743 /// or downcast between respective pointers or references.
744 static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
746 SourceRange OpRange) {
747 QualType SrcType = SrcExpr->getType();
748 // When casting from pointer or reference, get pointee type; use original
750 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
751 const CXXRecordDecl *SrcRD =
752 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
754 // Examining subobjects for records is only possible if the complete and
755 // valid definition is available. Also, template instantiation is not
757 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
760 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
762 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
770 CXXBasePaths BasePaths;
772 if (SrcRD->isDerivedFrom(DestRD, BasePaths))
773 ReinterpretKind = ReinterpretUpcast;
774 else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
775 ReinterpretKind = ReinterpretDowncast;
779 bool VirtualBase = true;
780 bool NonZeroOffset = false;
781 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
784 const CXXBasePath &Path = *I;
785 CharUnits Offset = CharUnits::Zero();
786 bool IsVirtual = false;
787 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
788 IElem != EElem; ++IElem) {
789 IsVirtual = IElem->Base->isVirtual();
792 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
793 assert(BaseRD && "Base type should be a valid unqualified class type");
794 // Don't check if any base has invalid declaration or has no definition
795 // since it has no layout info.
796 const CXXRecordDecl *Class = IElem->Class,
797 *ClassDefinition = Class->getDefinition();
798 if (Class->isInvalidDecl() || !ClassDefinition ||
799 !ClassDefinition->isCompleteDefinition())
802 const ASTRecordLayout &DerivedLayout =
803 Self.Context.getASTRecordLayout(Class);
804 Offset += DerivedLayout.getBaseClassOffset(BaseRD);
807 // Don't warn if any path is a non-virtually derived base at offset zero.
810 // Offset makes sense only for non-virtual bases.
812 NonZeroOffset = true;
814 VirtualBase = VirtualBase && IsVirtual;
817 (void) NonZeroOffset; // Silence set but not used warning.
818 assert((VirtualBase || NonZeroOffset) &&
819 "Should have returned if has non-virtual base with zero offset");
822 ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
823 QualType DerivedType =
824 ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
826 SourceLocation BeginLoc = OpRange.getBegin();
827 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
828 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
830 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
831 << int(ReinterpretKind)
832 << FixItHint::CreateReplacement(BeginLoc, "static_cast");
835 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
837 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
839 /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
840 void CastOperation::CheckReinterpretCast() {
841 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload))
842 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
844 checkNonOverloadPlaceholders();
845 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
848 unsigned msg = diag::err_bad_cxx_cast_generic;
850 TryReinterpretCast(Self, SrcExpr, DestType,
851 /*CStyle*/false, OpRange, msg, Kind);
852 if (tcr != TC_Success && msg != 0)
854 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
856 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
857 //FIXME: &f<int>; is overloaded and resolvable
858 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
859 << OverloadExpr::find(SrcExpr.get()).Expression->getName()
860 << DestType << OpRange;
861 Self.NoteAllOverloadCandidates(SrcExpr.get());
864 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
865 DestType, /*listInitialization=*/false);
867 SrcExpr = ExprError();
868 } else if (tcr == TC_Success) {
869 if (Self.getLangOpts().ObjCAutoRefCount)
870 checkObjCARCConversion(Sema::CCK_OtherCast);
871 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
876 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
877 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
878 /// implicit conversions explicit and getting rid of data loss warnings.
879 void CastOperation::CheckStaticCast() {
880 if (isPlaceholder()) {
881 checkNonOverloadPlaceholders();
882 if (SrcExpr.isInvalid())
886 // This test is outside everything else because it's the only case where
887 // a non-lvalue-reference target type does not lead to decay.
888 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
889 if (DestType->isVoidType()) {
892 if (claimPlaceholder(BuiltinType::Overload)) {
893 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
894 false, // Decay Function to ptr
896 OpRange, DestType, diag::err_bad_static_cast_overload);
897 if (SrcExpr.isInvalid())
901 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
905 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
906 !isPlaceholder(BuiltinType::Overload)) {
907 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
908 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
912 unsigned msg = diag::err_bad_cxx_cast_generic;
914 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
915 Kind, BasePath, /*ListInitialization=*/false);
916 if (tcr != TC_Success && msg != 0) {
917 if (SrcExpr.isInvalid())
919 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
920 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
921 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
922 << oe->getName() << DestType << OpRange
923 << oe->getQualifierLoc().getSourceRange();
924 Self.NoteAllOverloadCandidates(SrcExpr.get());
926 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
927 /*listInitialization=*/false);
929 SrcExpr = ExprError();
930 } else if (tcr == TC_Success) {
931 if (Kind == CK_BitCast)
933 if (Self.getLangOpts().ObjCAutoRefCount)
934 checkObjCARCConversion(Sema::CCK_OtherCast);
935 } else if (Kind == CK_BitCast) {
940 /// TryStaticCast - Check if a static cast can be performed, and do so if
941 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
942 /// and casting away constness.
943 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
945 Sema::CheckedConversionKind CCK,
946 const SourceRange &OpRange, unsigned &msg,
947 CastKind &Kind, CXXCastPath &BasePath,
948 bool ListInitialization) {
949 // Determine whether we have the semantics of a C-style cast.
951 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
953 // The order the tests is not entirely arbitrary. There is one conversion
954 // that can be handled in two different ways. Given:
956 // struct B : public A {
960 // the cast static_cast<const B&>(a) could be seen as either a static
961 // reference downcast, or an explicit invocation of the user-defined
962 // conversion using B's conversion constructor.
963 // DR 427 specifies that the downcast is to be applied here.
965 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
966 // Done outside this function.
970 // C++ 5.2.9p5, reference downcast.
971 // See the function for details.
972 // DR 427 specifies that this is to be applied before paragraph 2.
973 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle,
974 OpRange, msg, Kind, BasePath);
975 if (tcr != TC_NotApplicable)
978 // C++0x [expr.static.cast]p3:
979 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
980 // T2" if "cv2 T2" is reference-compatible with "cv1 T1".
981 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind,
983 if (tcr != TC_NotApplicable)
986 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
987 // [...] if the declaration "T t(e);" is well-formed, [...].
988 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
989 Kind, ListInitialization);
990 if (SrcExpr.isInvalid())
992 if (tcr != TC_NotApplicable)
995 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
996 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
997 // conversions, subject to further restrictions.
998 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
999 // of qualification conversions impossible.
1000 // In the CStyle case, the earlier attempt to const_cast should have taken
1001 // care of reverse qualification conversions.
1003 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
1005 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
1006 // converted to an integral type. [...] A value of a scoped enumeration type
1007 // can also be explicitly converted to a floating-point type [...].
1008 if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
1009 if (Enum->getDecl()->isScoped()) {
1010 if (DestType->isBooleanType()) {
1011 Kind = CK_IntegralToBoolean;
1013 } else if (DestType->isIntegralType(Self.Context)) {
1014 Kind = CK_IntegralCast;
1016 } else if (DestType->isRealFloatingType()) {
1017 Kind = CK_IntegralToFloating;
1023 // Reverse integral promotion/conversion. All such conversions are themselves
1024 // again integral promotions or conversions and are thus already handled by
1025 // p2 (TryDirectInitialization above).
1026 // (Note: any data loss warnings should be suppressed.)
1027 // The exception is the reverse of enum->integer, i.e. integer->enum (and
1028 // enum->enum). See also C++ 5.2.9p7.
1029 // The same goes for reverse floating point promotion/conversion and
1030 // floating-integral conversions. Again, only floating->enum is relevant.
1031 if (DestType->isEnumeralType()) {
1032 if (SrcType->isIntegralOrEnumerationType()) {
1033 Kind = CK_IntegralCast;
1035 } else if (SrcType->isRealFloatingType()) {
1036 Kind = CK_FloatingToIntegral;
1041 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
1042 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
1043 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
1045 if (tcr != TC_NotApplicable)
1048 // Reverse member pointer conversion. C++ 4.11 specifies member pointer
1049 // conversion. C++ 5.2.9p9 has additional information.
1050 // DR54's access restrictions apply here also.
1051 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
1052 OpRange, msg, Kind, BasePath);
1053 if (tcr != TC_NotApplicable)
1056 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
1057 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
1058 // just the usual constness stuff.
1059 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
1060 QualType SrcPointee = SrcPointer->getPointeeType();
1061 if (SrcPointee->isVoidType()) {
1062 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
1063 QualType DestPointee = DestPointer->getPointeeType();
1064 if (DestPointee->isIncompleteOrObjectType()) {
1065 // This is definitely the intended conversion, but it might fail due
1066 // to a qualifier violation. Note that we permit Objective-C lifetime
1067 // and GC qualifier mismatches here.
1069 Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
1070 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
1071 DestPointeeQuals.removeObjCGCAttr();
1072 DestPointeeQuals.removeObjCLifetime();
1073 SrcPointeeQuals.removeObjCGCAttr();
1074 SrcPointeeQuals.removeObjCLifetime();
1075 if (DestPointeeQuals != SrcPointeeQuals &&
1076 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
1077 msg = diag::err_bad_cxx_cast_qualifiers_away;
1085 // Microsoft permits static_cast from 'pointer-to-void' to
1086 // 'pointer-to-function'.
1087 if (!CStyle && Self.getLangOpts().MSVCCompat &&
1088 DestPointee->isFunctionType()) {
1089 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange;
1094 else if (DestType->isObjCObjectPointerType()) {
1095 // allow both c-style cast and static_cast of objective-c pointers as
1096 // they are pervasive.
1097 Kind = CK_CPointerToObjCPointerCast;
1100 else if (CStyle && DestType->isBlockPointerType()) {
1101 // allow c-style cast of void * to block pointers.
1102 Kind = CK_AnyPointerToBlockPointerCast;
1107 // Allow arbitray objective-c pointer conversion with static casts.
1108 if (SrcType->isObjCObjectPointerType() &&
1109 DestType->isObjCObjectPointerType()) {
1113 // Allow ns-pointer to cf-pointer conversion in either direction
1114 // with static casts.
1116 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind))
1119 // See if it looks like the user is trying to convert between
1120 // related record types, and select a better diagnostic if so.
1121 if (auto SrcPointer = SrcType->getAs<PointerType>())
1122 if (auto DestPointer = DestType->getAs<PointerType>())
1123 if (SrcPointer->getPointeeType()->getAs<RecordType>() &&
1124 DestPointer->getPointeeType()->getAs<RecordType>())
1125 msg = diag::err_bad_cxx_cast_unrelated_class;
1127 // We tried everything. Everything! Nothing works! :-(
1128 return TC_NotApplicable;
1131 /// Tests whether a conversion according to N2844 is valid.
1133 TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType,
1134 bool CStyle, CastKind &Kind, CXXCastPath &BasePath,
1136 // C++0x [expr.static.cast]p3:
1137 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
1138 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1139 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
1141 return TC_NotApplicable;
1143 if (!SrcExpr->isGLValue())
1144 return TC_NotApplicable;
1146 // Because we try the reference downcast before this function, from now on
1147 // this is the only cast possibility, so we issue an error if we fail now.
1148 // FIXME: Should allow casting away constness if CStyle.
1150 bool ObjCConversion;
1151 bool ObjCLifetimeConversion;
1152 QualType FromType = SrcExpr->getType();
1153 QualType ToType = R->getPointeeType();
1155 FromType = FromType.getUnqualifiedType();
1156 ToType = ToType.getUnqualifiedType();
1159 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(),
1161 DerivedToBase, ObjCConversion,
1162 ObjCLifetimeConversion)
1163 < Sema::Ref_Compatible_With_Added_Qualification) {
1164 msg = diag::err_bad_lvalue_to_rvalue_cast;
1168 if (DerivedToBase) {
1169 Kind = CK_DerivedToBase;
1170 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1171 /*DetectVirtual=*/true);
1172 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths))
1173 return TC_NotApplicable;
1175 Self.BuildBasePathArray(Paths, BasePath);
1182 /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
1184 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
1185 bool CStyle, const SourceRange &OpRange,
1186 unsigned &msg, CastKind &Kind,
1187 CXXCastPath &BasePath) {
1188 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
1189 // cast to type "reference to cv2 D", where D is a class derived from B,
1190 // if a valid standard conversion from "pointer to D" to "pointer to B"
1191 // exists, cv2 >= cv1, and B is not a virtual base class of D.
1192 // In addition, DR54 clarifies that the base must be accessible in the
1193 // current context. Although the wording of DR54 only applies to the pointer
1194 // variant of this rule, the intent is clearly for it to apply to the this
1195 // conversion as well.
1197 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
1198 if (!DestReference) {
1199 return TC_NotApplicable;
1201 bool RValueRef = DestReference->isRValueReferenceType();
1202 if (!RValueRef && !SrcExpr->isLValue()) {
1203 // We know the left side is an lvalue reference, so we can suggest a reason.
1204 msg = diag::err_bad_cxx_cast_rvalue;
1205 return TC_NotApplicable;
1208 QualType DestPointee = DestReference->getPointeeType();
1210 // FIXME: If the source is a prvalue, we should issue a warning (because the
1211 // cast always has undefined behavior), and for AST consistency, we should
1212 // materialize a temporary.
1213 return TryStaticDowncast(Self,
1214 Self.Context.getCanonicalType(SrcExpr->getType()),
1215 Self.Context.getCanonicalType(DestPointee), CStyle,
1216 OpRange, SrcExpr->getType(), DestType, msg, Kind,
1220 /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
1222 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
1223 bool CStyle, const SourceRange &OpRange,
1224 unsigned &msg, CastKind &Kind,
1225 CXXCastPath &BasePath) {
1226 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
1227 // type, can be converted to an rvalue of type "pointer to cv2 D", where D
1228 // is a class derived from B, if a valid standard conversion from "pointer
1229 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
1231 // In addition, DR54 clarifies that the base must be accessible in the
1234 const PointerType *DestPointer = DestType->getAs<PointerType>();
1236 return TC_NotApplicable;
1239 const PointerType *SrcPointer = SrcType->getAs<PointerType>();
1241 msg = diag::err_bad_static_cast_pointer_nonpointer;
1242 return TC_NotApplicable;
1245 return TryStaticDowncast(Self,
1246 Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
1247 Self.Context.getCanonicalType(DestPointer->getPointeeType()),
1248 CStyle, OpRange, SrcType, DestType, msg, Kind,
1252 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
1253 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
1254 /// DestType is possible and allowed.
1256 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
1257 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType,
1258 QualType OrigDestType, unsigned &msg,
1259 CastKind &Kind, CXXCastPath &BasePath) {
1260 // We can only work with complete types. But don't complain if it doesn't work
1261 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, 0) ||
1262 Self.RequireCompleteType(OpRange.getBegin(), DestType, 0))
1263 return TC_NotApplicable;
1265 // Downcast can only happen in class hierarchies, so we need classes.
1266 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
1267 return TC_NotApplicable;
1270 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1271 /*DetectVirtual=*/true);
1272 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) {
1273 return TC_NotApplicable;
1276 // Target type does derive from source type. Now we're serious. If an error
1277 // appears now, it's not ignored.
1278 // This may not be entirely in line with the standard. Take for example:
1280 // struct B : virtual A {
1286 // (void)static_cast<const B&>(*((A*)0));
1288 // As far as the standard is concerned, p5 does not apply (A is virtual), so
1289 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
1290 // However, both GCC and Comeau reject this example, and accepting it would
1291 // mean more complex code if we're to preserve the nice error message.
1292 // FIXME: Being 100% compliant here would be nice to have.
1294 // Must preserve cv, as always, unless we're in C-style mode.
1295 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
1296 msg = diag::err_bad_cxx_cast_qualifiers_away;
1300 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
1301 // This code is analoguous to that in CheckDerivedToBaseConversion, except
1302 // that it builds the paths in reverse order.
1303 // To sum up: record all paths to the base and build a nice string from
1304 // them. Use it to spice up the error message.
1305 if (!Paths.isRecordingPaths()) {
1307 Paths.setRecordingPaths(true);
1308 Self.IsDerivedFrom(DestType, SrcType, Paths);
1310 std::string PathDisplayStr;
1311 std::set<unsigned> DisplayedPaths;
1312 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end();
1314 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) {
1315 // We haven't displayed a path to this particular base
1316 // class subobject yet.
1317 PathDisplayStr += "\n ";
1318 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(),
1321 PathDisplayStr += EI->Base->getType().getAsString() + " -> ";
1322 PathDisplayStr += QualType(DestType).getAsString();
1326 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
1327 << QualType(SrcType).getUnqualifiedType()
1328 << QualType(DestType).getUnqualifiedType()
1329 << PathDisplayStr << OpRange;
1334 if (Paths.getDetectedVirtual() != nullptr) {
1335 QualType VirtualBase(Paths.getDetectedVirtual(), 0);
1336 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
1337 << OrigSrcType << OrigDestType << VirtualBase << OpRange;
1343 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1346 diag::err_downcast_from_inaccessible_base)) {
1347 case Sema::AR_accessible:
1348 case Sema::AR_delayed: // be optimistic
1349 case Sema::AR_dependent: // be optimistic
1352 case Sema::AR_inaccessible:
1358 Self.BuildBasePathArray(Paths, BasePath);
1359 Kind = CK_BaseToDerived;
1363 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
1364 /// C++ 5.2.9p9 is valid:
1366 /// An rvalue of type "pointer to member of D of type cv1 T" can be
1367 /// converted to an rvalue of type "pointer to member of B of type cv2 T",
1368 /// where B is a base class of D [...].
1371 TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
1372 QualType DestType, bool CStyle,
1373 const SourceRange &OpRange,
1374 unsigned &msg, CastKind &Kind,
1375 CXXCastPath &BasePath) {
1376 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
1378 return TC_NotApplicable;
1380 bool WasOverloadedFunction = false;
1381 DeclAccessPair FoundOverload;
1382 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1383 if (FunctionDecl *Fn
1384 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
1386 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
1387 SrcType = Self.Context.getMemberPointerType(Fn->getType(),
1388 Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
1389 WasOverloadedFunction = true;
1393 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1395 msg = diag::err_bad_static_cast_member_pointer_nonmp;
1396 return TC_NotApplicable;
1399 // T == T, modulo cv
1400 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
1401 DestMemPtr->getPointeeType()))
1402 return TC_NotApplicable;
1405 QualType SrcClass(SrcMemPtr->getClass(), 0);
1406 QualType DestClass(DestMemPtr->getClass(), 0);
1407 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1408 /*DetectVirtual=*/true);
1409 if (Self.RequireCompleteType(OpRange.getBegin(), SrcClass, 0) ||
1410 !Self.IsDerivedFrom(SrcClass, DestClass, Paths)) {
1411 return TC_NotApplicable;
1414 // B is a base of D. But is it an allowed base? If not, it's a hard error.
1415 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
1417 Paths.setRecordingPaths(true);
1418 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths);
1421 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
1422 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
1423 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
1428 if (const RecordType *VBase = Paths.getDetectedVirtual()) {
1429 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
1430 << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
1436 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1437 DestClass, SrcClass,
1439 diag::err_upcast_to_inaccessible_base)) {
1440 case Sema::AR_accessible:
1441 case Sema::AR_delayed:
1442 case Sema::AR_dependent:
1443 // Optimistically assume that the delayed and dependent cases
1447 case Sema::AR_inaccessible:
1453 if (WasOverloadedFunction) {
1454 // Resolve the address of the overloaded function again, this time
1455 // allowing complaints if something goes wrong.
1456 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
1465 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
1466 if (!SrcExpr.isUsable()) {
1472 Self.BuildBasePathArray(Paths, BasePath);
1473 Kind = CK_DerivedToBaseMemberPointer;
1477 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
1480 /// An expression e can be explicitly converted to a type T using a
1481 /// @c static_cast if the declaration "T t(e);" is well-formed [...].
1483 TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
1484 Sema::CheckedConversionKind CCK,
1485 const SourceRange &OpRange, unsigned &msg,
1486 CastKind &Kind, bool ListInitialization) {
1487 if (DestType->isRecordType()) {
1488 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1489 diag::err_bad_dynamic_cast_incomplete) ||
1490 Self.RequireNonAbstractType(OpRange.getBegin(), DestType,
1491 diag::err_allocation_of_abstract_type)) {
1495 } else if (DestType->isMemberPointerType()) {
1496 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
1497 Self.RequireCompleteType(OpRange.getBegin(), DestType, 0);
1501 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
1502 InitializationKind InitKind
1503 = (CCK == Sema::CCK_CStyleCast)
1504 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange,
1506 : (CCK == Sema::CCK_FunctionalCast)
1507 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization)
1508 : InitializationKind::CreateCast(OpRange);
1509 Expr *SrcExprRaw = SrcExpr.get();
1510 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
1512 // At this point of CheckStaticCast, if the destination is a reference,
1513 // or the expression is an overload expression this has to work.
1514 // There is no other way that works.
1515 // On the other hand, if we're checking a C-style cast, we've still got
1516 // the reinterpret_cast way.
1518 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
1519 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
1520 return TC_NotApplicable;
1522 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw);
1523 if (Result.isInvalid()) {
1528 if (InitSeq.isConstructorInitialization())
1529 Kind = CK_ConstructorConversion;
1537 /// TryConstCast - See if a const_cast from source to destination is allowed,
1538 /// and perform it if it is.
1539 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
1540 QualType DestType, bool CStyle,
1542 DestType = Self.Context.getCanonicalType(DestType);
1543 QualType SrcType = SrcExpr.get()->getType();
1544 bool NeedToMaterializeTemporary = false;
1546 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
1548 // if a pointer to T1 can be explicitly converted to the type "pointer to
1549 // T2" using a const_cast, then the following conversions can also be
1551 // -- an lvalue of type T1 can be explicitly converted to an lvalue of
1552 // type T2 using the cast const_cast<T2&>;
1553 // -- a glvalue of type T1 can be explicitly converted to an xvalue of
1554 // type T2 using the cast const_cast<T2&&>; and
1555 // -- if T1 is a class type, a prvalue of type T1 can be explicitly
1556 // converted to an xvalue of type T2 using the cast const_cast<T2&&>.
1558 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) {
1559 // Cannot const_cast non-lvalue to lvalue reference type. But if this
1560 // is C-style, static_cast might find a way, so we simply suggest a
1561 // message and tell the parent to keep searching.
1562 msg = diag::err_bad_cxx_cast_rvalue;
1563 return TC_NotApplicable;
1566 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) {
1567 if (!SrcType->isRecordType()) {
1568 // Cannot const_cast non-class prvalue to rvalue reference type. But if
1569 // this is C-style, static_cast can do this.
1570 msg = diag::err_bad_cxx_cast_rvalue;
1571 return TC_NotApplicable;
1574 // Materialize the class prvalue so that the const_cast can bind a
1576 NeedToMaterializeTemporary = true;
1579 // It's not completely clear under the standard whether we can
1580 // const_cast bit-field gl-values. Doing so would not be
1581 // intrinsically complicated, but for now, we say no for
1582 // consistency with other compilers and await the word of the
1584 if (SrcExpr.get()->refersToBitField()) {
1585 msg = diag::err_bad_cxx_cast_bitfield;
1586 return TC_NotApplicable;
1589 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1590 SrcType = Self.Context.getPointerType(SrcType);
1593 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
1594 // the rules for const_cast are the same as those used for pointers.
1596 if (!DestType->isPointerType() &&
1597 !DestType->isMemberPointerType() &&
1598 !DestType->isObjCObjectPointerType()) {
1599 // Cannot cast to non-pointer, non-reference type. Note that, if DestType
1600 // was a reference type, we converted it to a pointer above.
1601 // The status of rvalue references isn't entirely clear, but it looks like
1602 // conversion to them is simply invalid.
1603 // C++ 5.2.11p3: For two pointer types [...]
1605 msg = diag::err_bad_const_cast_dest;
1606 return TC_NotApplicable;
1608 if (DestType->isFunctionPointerType() ||
1609 DestType->isMemberFunctionPointerType()) {
1610 // Cannot cast direct function pointers.
1611 // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
1612 // T is the ultimate pointee of source and target type.
1614 msg = diag::err_bad_const_cast_dest;
1615 return TC_NotApplicable;
1617 SrcType = Self.Context.getCanonicalType(SrcType);
1619 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are
1620 // completely equal.
1621 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers
1622 // in multi-level pointers may change, but the level count must be the same,
1623 // as must be the final pointee type.
1624 while (SrcType != DestType &&
1625 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) {
1626 Qualifiers SrcQuals, DestQuals;
1627 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals);
1628 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals);
1630 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that
1631 // the other qualifiers (e.g., address spaces) are identical.
1632 SrcQuals.removeCVRQualifiers();
1633 DestQuals.removeCVRQualifiers();
1634 if (SrcQuals != DestQuals)
1635 return TC_NotApplicable;
1638 // Since we're dealing in canonical types, the remainder must be the same.
1639 if (SrcType != DestType)
1640 return TC_NotApplicable;
1642 if (NeedToMaterializeTemporary)
1643 // This is a const_cast from a class prvalue to an rvalue reference type.
1644 // Materialize a temporary to store the result of the conversion.
1645 SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
1646 SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
1651 // Checks for undefined behavior in reinterpret_cast.
1652 // The cases that is checked for is:
1653 // *reinterpret_cast<T*>(&a)
1654 // reinterpret_cast<T&>(a)
1655 // where accessing 'a' as type 'T' will result in undefined behavior.
1656 void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
1658 SourceRange Range) {
1659 unsigned DiagID = IsDereference ?
1660 diag::warn_pointer_indirection_from_incompatible_type :
1661 diag::warn_undefined_reinterpret_cast;
1663 if (Diags.isIgnored(DiagID, Range.getBegin()))
1666 QualType SrcTy, DestTy;
1667 if (IsDereference) {
1668 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
1671 SrcTy = SrcType->getPointeeType();
1672 DestTy = DestType->getPointeeType();
1674 if (!DestType->getAs<ReferenceType>()) {
1678 DestTy = DestType->getPointeeType();
1681 // Cast is compatible if the types are the same.
1682 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
1685 // or one of the types is a char or void type
1686 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
1687 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
1690 // or one of the types is a tag type.
1691 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
1695 // FIXME: Scoped enums?
1696 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
1697 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
1698 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
1703 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
1706 static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr,
1707 QualType DestType) {
1708 QualType SrcType = SrcExpr.get()->getType();
1709 if (Self.Context.hasSameType(SrcType, DestType))
1711 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>())
1712 if (SrcPtrTy->isObjCSelType()) {
1713 QualType DT = DestType;
1714 if (isa<PointerType>(DestType))
1715 DT = DestType->getPointeeType();
1716 if (!DT.getUnqualifiedType()->isVoidType())
1717 Self.Diag(SrcExpr.get()->getExprLoc(),
1718 diag::warn_cast_pointer_from_sel)
1719 << SrcType << DestType << SrcExpr.get()->getSourceRange();
1723 static void checkIntToPointerCast(bool CStyle, SourceLocation Loc,
1724 const Expr *SrcExpr, QualType DestType,
1726 QualType SrcType = SrcExpr->getType();
1728 // Not warning on reinterpret_cast, boolean, constant expressions, etc
1729 // are not explicit design choices, but consistent with GCC's behavior.
1730 // Feel free to modify them if you've reason/evidence for an alternative.
1731 if (CStyle && SrcType->isIntegralType(Self.Context)
1732 && !SrcType->isBooleanType()
1733 && !SrcType->isEnumeralType()
1734 && !SrcExpr->isIntegerConstantExpr(Self.Context)
1735 && Self.Context.getTypeSize(DestType) >
1736 Self.Context.getTypeSize(SrcType)) {
1737 // Separate between casts to void* and non-void* pointers.
1738 // Some APIs use (abuse) void* for something like a user context,
1739 // and often that value is an integer even if it isn't a pointer itself.
1740 // Having a separate warning flag allows users to control the warning
1741 // for their workflow.
1742 unsigned Diag = DestType->isVoidPointerType() ?
1743 diag::warn_int_to_void_pointer_cast
1744 : diag::warn_int_to_pointer_cast;
1745 Self.Diag(Loc, Diag) << SrcType << DestType;
1749 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
1750 QualType DestType, bool CStyle,
1751 const SourceRange &OpRange,
1754 bool IsLValueCast = false;
1756 DestType = Self.Context.getCanonicalType(DestType);
1757 QualType SrcType = SrcExpr.get()->getType();
1759 // Is the source an overloaded name? (i.e. &foo)
1760 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ...
1761 if (SrcType == Self.Context.OverloadTy) {
1762 // ... unless foo<int> resolves to an lvalue unambiguously.
1763 // TODO: what if this fails because of DiagnoseUseOfDecl or something
1765 ExprResult SingleFunctionExpr = SrcExpr;
1766 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization(
1768 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr
1769 ) && SingleFunctionExpr.isUsable()) {
1770 SrcExpr = SingleFunctionExpr;
1771 SrcType = SrcExpr.get()->getType();
1773 return TC_NotApplicable;
1777 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
1778 if (!SrcExpr.get()->isGLValue()) {
1779 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
1780 // similar comment in const_cast.
1781 msg = diag::err_bad_cxx_cast_rvalue;
1782 return TC_NotApplicable;
1786 Self.CheckCompatibleReinterpretCast(SrcType, DestType,
1787 /*isDereference=*/false, OpRange);
1790 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
1791 // same effect as the conversion *reinterpret_cast<T*>(&x) with the
1792 // built-in & and * operators.
1794 const char *inappropriate = nullptr;
1795 switch (SrcExpr.get()->getObjectKind()) {
1798 case OK_BitField: inappropriate = "bit-field"; break;
1799 case OK_VectorComponent: inappropriate = "vector element"; break;
1800 case OK_ObjCProperty: inappropriate = "property expression"; break;
1801 case OK_ObjCSubscript: inappropriate = "container subscripting expression";
1804 if (inappropriate) {
1805 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
1806 << inappropriate << DestType
1807 << OpRange << SrcExpr.get()->getSourceRange();
1808 msg = 0; SrcExpr = ExprError();
1809 return TC_NotApplicable;
1812 // This code does this transformation for the checked types.
1813 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1814 SrcType = Self.Context.getPointerType(SrcType);
1816 IsLValueCast = true;
1819 // Canonicalize source for comparison.
1820 SrcType = Self.Context.getCanonicalType(SrcType);
1822 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
1823 *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1824 if (DestMemPtr && SrcMemPtr) {
1825 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
1826 // can be explicitly converted to an rvalue of type "pointer to member
1827 // of Y of type T2" if T1 and T2 are both function types or both object
1829 if (DestMemPtr->isMemberFunctionPointer() !=
1830 SrcMemPtr->isMemberFunctionPointer())
1831 return TC_NotApplicable;
1833 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
1835 // A reinterpret_cast followed by a const_cast can, though, so in C-style,
1837 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1838 /*CheckObjCLifetime=*/CStyle)) {
1839 msg = diag::err_bad_cxx_cast_qualifiers_away;
1843 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
1844 // We need to determine the inheritance model that the class will use if
1846 Self.RequireCompleteType(OpRange.getBegin(), SrcType, 0);
1847 Self.RequireCompleteType(OpRange.getBegin(), DestType, 0);
1850 // Don't allow casting between member pointers of different sizes.
1851 if (Self.Context.getTypeSize(DestMemPtr) !=
1852 Self.Context.getTypeSize(SrcMemPtr)) {
1853 msg = diag::err_bad_cxx_cast_member_pointer_size;
1857 // A valid member pointer cast.
1858 assert(!IsLValueCast);
1859 Kind = CK_ReinterpretMemberPointer;
1863 // See below for the enumeral issue.
1864 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
1865 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
1866 // type large enough to hold it. A value of std::nullptr_t can be
1867 // converted to an integral type; the conversion has the same meaning
1868 // and validity as a conversion of (void*)0 to the integral type.
1869 if (Self.Context.getTypeSize(SrcType) >
1870 Self.Context.getTypeSize(DestType)) {
1871 msg = diag::err_bad_reinterpret_cast_small_int;
1874 Kind = CK_PointerToIntegral;
1878 bool destIsVector = DestType->isVectorType();
1879 bool srcIsVector = SrcType->isVectorType();
1880 if (srcIsVector || destIsVector) {
1881 // FIXME: Should this also apply to floating point types?
1882 bool srcIsScalar = SrcType->isIntegralType(Self.Context);
1883 bool destIsScalar = DestType->isIntegralType(Self.Context);
1885 // Check if this is a cast between a vector and something else.
1886 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) &&
1887 !(srcIsVector && destIsVector))
1888 return TC_NotApplicable;
1890 // If both types have the same size, we can successfully cast.
1891 if (Self.Context.getTypeSize(SrcType)
1892 == Self.Context.getTypeSize(DestType)) {
1898 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
1899 else if (srcIsScalar)
1900 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
1902 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
1907 if (SrcType == DestType) {
1908 // C++ 5.2.10p2 has a note that mentions that, subject to all other
1909 // restrictions, a cast to the same type is allowed so long as it does not
1910 // cast away constness. In C++98, the intent was not entirely clear here,
1911 // since all other paragraphs explicitly forbid casts to the same type.
1912 // C++11 clarifies this case with p2.
1914 // The only allowed types are: integral, enumeration, pointer, or
1915 // pointer-to-member types. We also won't restrict Obj-C pointers either.
1917 TryCastResult Result = TC_NotApplicable;
1918 if (SrcType->isIntegralOrEnumerationType() ||
1919 SrcType->isAnyPointerType() ||
1920 SrcType->isMemberPointerType() ||
1921 SrcType->isBlockPointerType()) {
1922 Result = TC_Success;
1927 bool destIsPtr = DestType->isAnyPointerType() ||
1928 DestType->isBlockPointerType();
1929 bool srcIsPtr = SrcType->isAnyPointerType() ||
1930 SrcType->isBlockPointerType();
1931 if (!destIsPtr && !srcIsPtr) {
1932 // Except for std::nullptr_t->integer and lvalue->reference, which are
1933 // handled above, at least one of the two arguments must be a pointer.
1934 return TC_NotApplicable;
1937 if (DestType->isIntegralType(Self.Context)) {
1938 assert(srcIsPtr && "One type must be a pointer");
1939 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
1940 // type large enough to hold it; except in Microsoft mode, where the
1941 // integral type size doesn't matter (except we don't allow bool).
1942 bool MicrosoftException = Self.getLangOpts().MicrosoftExt &&
1943 !DestType->isBooleanType();
1944 if ((Self.Context.getTypeSize(SrcType) >
1945 Self.Context.getTypeSize(DestType)) &&
1946 !MicrosoftException) {
1947 msg = diag::err_bad_reinterpret_cast_small_int;
1950 Kind = CK_PointerToIntegral;
1954 if (SrcType->isIntegralOrEnumerationType()) {
1955 assert(destIsPtr && "One type must be a pointer");
1956 checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType,
1958 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
1959 // converted to a pointer.
1960 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
1961 // necessarily converted to a null pointer value.]
1962 Kind = CK_IntegralToPointer;
1966 if (!destIsPtr || !srcIsPtr) {
1967 // With the valid non-pointer conversions out of the way, we can be even
1969 return TC_NotApplicable;
1972 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
1973 // The C-style cast operator can.
1974 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1975 /*CheckObjCLifetime=*/CStyle)) {
1976 msg = diag::err_bad_cxx_cast_qualifiers_away;
1980 // Cannot convert between block pointers and Objective-C object pointers.
1981 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
1982 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
1983 return TC_NotApplicable;
1986 Kind = CK_LValueBitCast;
1987 } else if (DestType->isObjCObjectPointerType()) {
1988 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr);
1989 } else if (DestType->isBlockPointerType()) {
1990 if (!SrcType->isBlockPointerType()) {
1991 Kind = CK_AnyPointerToBlockPointerCast;
1999 // Any pointer can be cast to an Objective-C pointer type with a C-style
2001 if (CStyle && DestType->isObjCObjectPointerType()) {
2005 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2007 // Not casting away constness, so the only remaining check is for compatible
2008 // pointer categories.
2010 if (SrcType->isFunctionPointerType()) {
2011 if (DestType->isFunctionPointerType()) {
2012 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
2013 // a pointer to a function of a different type.
2017 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
2018 // an object type or vice versa is conditionally-supported.
2019 // Compilers support it in C++03 too, though, because it's necessary for
2020 // casting the return value of dlsym() and GetProcAddress().
2021 // FIXME: Conditionally-supported behavior should be configurable in the
2022 // TargetInfo or similar.
2023 Self.Diag(OpRange.getBegin(),
2024 Self.getLangOpts().CPlusPlus11 ?
2025 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2030 if (DestType->isFunctionPointerType()) {
2032 Self.Diag(OpRange.getBegin(),
2033 Self.getLangOpts().CPlusPlus11 ?
2034 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2039 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
2040 // a pointer to an object of different type.
2041 // Void pointers are not specified, but supported by every compiler out there.
2042 // So we finish by allowing everything that remains - it's got to be two
2047 void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
2048 bool ListInitialization) {
2049 // Handle placeholders.
2050 if (isPlaceholder()) {
2051 // C-style casts can resolve __unknown_any types.
2052 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2053 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2054 SrcExpr.get(), Kind,
2055 ValueKind, BasePath);
2059 checkNonOverloadPlaceholders();
2060 if (SrcExpr.isInvalid())
2064 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
2065 // This test is outside everything else because it's the only case where
2066 // a non-lvalue-reference target type does not lead to decay.
2067 if (DestType->isVoidType()) {
2070 if (claimPlaceholder(BuiltinType::Overload)) {
2071 Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2072 SrcExpr, /* Decay Function to ptr */ false,
2073 /* Complain */ true, DestRange, DestType,
2074 diag::err_bad_cstyle_cast_overload);
2075 if (SrcExpr.isInvalid())
2079 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2083 // If the type is dependent, we won't do any other semantic analysis now.
2084 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
2085 SrcExpr.get()->isValueDependent()) {
2086 assert(Kind == CK_Dependent);
2090 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
2091 !isPlaceholder(BuiltinType::Overload)) {
2092 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2093 if (SrcExpr.isInvalid())
2097 // AltiVec vector initialization with a single literal.
2098 if (const VectorType *vecTy = DestType->getAs<VectorType>())
2099 if (vecTy->getVectorKind() == VectorType::AltiVecVector
2100 && (SrcExpr.get()->getType()->isIntegerType()
2101 || SrcExpr.get()->getType()->isFloatingType())) {
2102 Kind = CK_VectorSplat;
2106 // C++ [expr.cast]p5: The conversions performed by
2109 // - a static_cast followed by a const_cast,
2110 // - a reinterpret_cast, or
2111 // - a reinterpret_cast followed by a const_cast,
2112 // can be performed using the cast notation of explicit type conversion.
2113 // [...] If a conversion can be interpreted in more than one of the ways
2114 // listed above, the interpretation that appears first in the list is used,
2115 // even if a cast resulting from that interpretation is ill-formed.
2116 // In plain language, this means trying a const_cast ...
2117 unsigned msg = diag::err_bad_cxx_cast_generic;
2118 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType,
2119 /*CStyle*/true, msg);
2120 if (SrcExpr.isInvalid())
2122 if (tcr == TC_Success)
2125 Sema::CheckedConversionKind CCK
2126 = FunctionalStyle? Sema::CCK_FunctionalCast
2127 : Sema::CCK_CStyleCast;
2128 if (tcr == TC_NotApplicable) {
2129 // ... or if that is not possible, a static_cast, ignoring const, ...
2130 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange,
2131 msg, Kind, BasePath, ListInitialization);
2132 if (SrcExpr.isInvalid())
2135 if (tcr == TC_NotApplicable) {
2136 // ... and finally a reinterpret_cast, ignoring const.
2137 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true,
2138 OpRange, msg, Kind);
2139 if (SrcExpr.isInvalid())
2144 if (Self.getLangOpts().ObjCAutoRefCount && tcr == TC_Success)
2145 checkObjCARCConversion(CCK);
2147 if (tcr != TC_Success && msg != 0) {
2148 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2149 DeclAccessPair Found;
2150 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
2155 // If DestType is a function type (not to be confused with the function
2156 // pointer type), it will be possible to resolve the function address,
2157 // but the type cast should be considered as failure.
2158 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression;
2159 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload)
2160 << OE->getName() << DestType << OpRange
2161 << OE->getQualifierLoc().getSourceRange();
2162 Self.NoteAllOverloadCandidates(SrcExpr.get());
2165 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
2166 OpRange, SrcExpr.get(), DestType, ListInitialization);
2168 } else if (Kind == CK_BitCast) {
2172 // Clear out SrcExpr if there was a fatal error.
2173 if (tcr != TC_Success)
2174 SrcExpr = ExprError();
2177 /// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
2178 /// non-matching type. Such as enum function call to int, int call to
2179 /// pointer; etc. Cast to 'void' is an exception.
2180 static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
2181 QualType DestType) {
2182 if (Self.Diags.isIgnored(diag::warn_bad_function_cast,
2183 SrcExpr.get()->getExprLoc()))
2186 if (!isa<CallExpr>(SrcExpr.get()))
2189 QualType SrcType = SrcExpr.get()->getType();
2190 if (DestType.getUnqualifiedType()->isVoidType())
2192 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType())
2193 && (DestType->isAnyPointerType() || DestType->isBlockPointerType()))
2195 if (SrcType->isIntegerType() && DestType->isIntegerType() &&
2196 (SrcType->isBooleanType() == DestType->isBooleanType()) &&
2197 (SrcType->isEnumeralType() == DestType->isEnumeralType()))
2199 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType())
2201 if (SrcType->isEnumeralType() && DestType->isEnumeralType())
2203 if (SrcType->isComplexType() && DestType->isComplexType())
2205 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType())
2208 Self.Diag(SrcExpr.get()->getExprLoc(),
2209 diag::warn_bad_function_cast)
2210 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2213 /// Check the semantics of a C-style cast operation, in C.
2214 void CastOperation::CheckCStyleCast() {
2215 assert(!Self.getLangOpts().CPlusPlus);
2217 // C-style casts can resolve __unknown_any types.
2218 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2219 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2220 SrcExpr.get(), Kind,
2221 ValueKind, BasePath);
2225 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression
2226 // type needs to be scalar.
2227 if (DestType->isVoidType()) {
2228 // We don't necessarily do lvalue-to-rvalue conversions on this.
2229 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2230 if (SrcExpr.isInvalid())
2233 // Cast to void allows any expr type.
2238 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2239 if (SrcExpr.isInvalid())
2241 QualType SrcType = SrcExpr.get()->getType();
2243 assert(!SrcType->isPlaceholderType());
2245 // OpenCL v1 s6.5: Casting a pointer to address space A to a pointer to
2246 // address space B is illegal.
2247 if (Self.getLangOpts().OpenCL && DestType->isPointerType() &&
2248 SrcType->isPointerType()) {
2249 const PointerType *DestPtr = DestType->getAs<PointerType>();
2250 if (!DestPtr->isAddressSpaceOverlapping(*SrcType->getAs<PointerType>())) {
2251 Self.Diag(OpRange.getBegin(),
2252 diag::err_typecheck_incompatible_address_space)
2253 << SrcType << DestType << Sema::AA_Casting
2254 << SrcExpr.get()->getSourceRange();
2255 SrcExpr = ExprError();
2260 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
2261 diag::err_typecheck_cast_to_incomplete)) {
2262 SrcExpr = ExprError();
2266 if (!DestType->isScalarType() && !DestType->isVectorType()) {
2267 const RecordType *DestRecordTy = DestType->getAs<RecordType>();
2269 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){
2270 // GCC struct/union extension: allow cast to self.
2271 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar)
2272 << DestType << SrcExpr.get()->getSourceRange();
2277 // GCC's cast to union extension.
2278 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) {
2279 RecordDecl *RD = DestRecordTy->getDecl();
2280 RecordDecl::field_iterator Field, FieldEnd;
2281 for (Field = RD->field_begin(), FieldEnd = RD->field_end();
2282 Field != FieldEnd; ++Field) {
2283 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) &&
2284 !Field->isUnnamedBitfield()) {
2285 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
2286 << SrcExpr.get()->getSourceRange();
2290 if (Field == FieldEnd) {
2291 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type)
2292 << SrcType << SrcExpr.get()->getSourceRange();
2293 SrcExpr = ExprError();
2300 // Reject any other conversions to non-scalar types.
2301 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar)
2302 << DestType << SrcExpr.get()->getSourceRange();
2303 SrcExpr = ExprError();
2307 // The type we're casting to is known to be a scalar or vector.
2309 // Require the operand to be a scalar or vector.
2310 if (!SrcType->isScalarType() && !SrcType->isVectorType()) {
2311 Self.Diag(SrcExpr.get()->getExprLoc(),
2312 diag::err_typecheck_expect_scalar_operand)
2313 << SrcType << SrcExpr.get()->getSourceRange();
2314 SrcExpr = ExprError();
2318 if (DestType->isExtVectorType()) {
2319 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind);
2323 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) {
2324 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector &&
2325 (SrcType->isIntegerType() || SrcType->isFloatingType())) {
2326 Kind = CK_VectorSplat;
2327 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) {
2328 SrcExpr = ExprError();
2333 if (SrcType->isVectorType()) {
2334 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind))
2335 SrcExpr = ExprError();
2339 // The source and target types are both scalars, i.e.
2340 // - arithmetic types (fundamental, enum, and complex)
2341 // - all kinds of pointers
2342 // Note that member pointers were filtered out with C++, above.
2344 if (isa<ObjCSelectorExpr>(SrcExpr.get())) {
2345 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr);
2346 SrcExpr = ExprError();
2350 // If either type is a pointer, the other type has to be either an
2351 // integer or a pointer.
2352 if (!DestType->isArithmeticType()) {
2353 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) {
2354 Self.Diag(SrcExpr.get()->getExprLoc(),
2355 diag::err_cast_pointer_from_non_pointer_int)
2356 << SrcType << SrcExpr.get()->getSourceRange();
2357 SrcExpr = ExprError();
2360 checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(),
2362 } else if (!SrcType->isArithmeticType()) {
2363 if (!DestType->isIntegralType(Self.Context) &&
2364 DestType->isArithmeticType()) {
2365 Self.Diag(SrcExpr.get()->getLocStart(),
2366 diag::err_cast_pointer_to_non_pointer_int)
2367 << DestType << SrcExpr.get()->getSourceRange();
2368 SrcExpr = ExprError();
2373 if (Self.getLangOpts().OpenCL && !Self.getOpenCLOptions().cl_khr_fp16) {
2374 if (DestType->isHalfType()) {
2375 Self.Diag(SrcExpr.get()->getLocStart(), diag::err_opencl_cast_to_half)
2376 << DestType << SrcExpr.get()->getSourceRange();
2377 SrcExpr = ExprError();
2382 // ARC imposes extra restrictions on casts.
2383 if (Self.getLangOpts().ObjCAutoRefCount) {
2384 checkObjCARCConversion(Sema::CCK_CStyleCast);
2385 if (SrcExpr.isInvalid())
2388 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) {
2389 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) {
2390 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers();
2391 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers();
2392 if (CastPtr->getPointeeType()->isObjCLifetimeType() &&
2393 ExprPtr->getPointeeType()->isObjCLifetimeType() &&
2394 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) {
2395 Self.Diag(SrcExpr.get()->getLocStart(),
2396 diag::err_typecheck_incompatible_ownership)
2397 << SrcType << DestType << Sema::AA_Casting
2398 << SrcExpr.get()->getSourceRange();
2403 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) {
2404 Self.Diag(SrcExpr.get()->getLocStart(),
2405 diag::err_arc_convesion_of_weak_unavailable)
2406 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2407 SrcExpr = ExprError();
2412 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2413 DiagnoseBadFunctionCast(Self, SrcExpr, DestType);
2414 Kind = Self.PrepareScalarCast(SrcExpr, DestType);
2415 if (SrcExpr.isInvalid())
2418 if (Kind == CK_BitCast)
2422 QualType TheOffendingSrcType, TheOffendingDestType;
2423 Qualifiers CastAwayQualifiers;
2424 if (SrcType->isAnyPointerType() && DestType->isAnyPointerType() &&
2425 CastsAwayConstness(Self, SrcType, DestType, true, false,
2426 &TheOffendingSrcType, &TheOffendingDestType,
2427 &CastAwayQualifiers)) {
2428 int qualifiers = -1;
2429 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) {
2431 } else if (CastAwayQualifiers.hasConst()) {
2433 } else if (CastAwayQualifiers.hasVolatile()) {
2436 // This is a variant of int **x; const int **y = (const int **)x;
2437 if (qualifiers == -1)
2438 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) <<
2439 SrcType << DestType;
2441 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) <<
2442 TheOffendingSrcType << TheOffendingDestType << qualifiers;
2446 ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
2447 TypeSourceInfo *CastTypeInfo,
2448 SourceLocation RPLoc,
2450 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
2451 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
2452 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd());
2454 if (getLangOpts().CPlusPlus) {
2455 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false,
2456 isa<InitListExpr>(CastExpr));
2458 Op.CheckCStyleCast();
2461 if (Op.SrcExpr.isInvalid())
2464 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType,
2465 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
2466 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc));
2469 ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo,
2470 SourceLocation LPLoc,
2472 SourceLocation RPLoc) {
2473 assert(LPLoc.isValid() && "List-initialization shouldn't get here.");
2474 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
2475 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
2476 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd());
2478 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/true, /*ListInit=*/false);
2479 if (Op.SrcExpr.isInvalid())
2482 if (CXXConstructExpr *ConstructExpr = dyn_cast<CXXConstructExpr>(Op.SrcExpr.get()))
2483 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc));
2485 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType,
2486 Op.ValueKind, CastTypeInfo, Op.Kind,
2487 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc));