1 //===--- SemaNamedCast.cpp - Semantic Analysis for Named 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 C++ named casts.
12 //===----------------------------------------------------------------------===//
14 #include "clang/Sema/SemaInternal.h"
15 #include "clang/Sema/Initialization.h"
16 #include "clang/AST/ExprCXX.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/CXXInheritance.h"
19 #include "clang/Basic/PartialDiagnostic.h"
20 #include "llvm/ADT/SmallVector.h"
22 using namespace clang;
27 TC_NotApplicable, ///< The cast method is not applicable.
28 TC_Success, ///< The cast method is appropriate and successful.
29 TC_Failed ///< The cast method is appropriate, but failed. A
30 ///< diagnostic has been emitted.
34 CT_Const, ///< const_cast
35 CT_Static, ///< static_cast
36 CT_Reinterpret, ///< reinterpret_cast
37 CT_Dynamic, ///< dynamic_cast
38 CT_CStyle, ///< (Type)expr
39 CT_Functional ///< Type(expr)
45 static void CheckConstCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
47 const SourceRange &OpRange,
48 const SourceRange &DestRange);
49 static void CheckReinterpretCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
51 const SourceRange &OpRange,
52 const SourceRange &DestRange,
54 static void CheckStaticCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
56 const SourceRange &OpRange,
58 CXXCastPath &BasePath);
59 static void CheckDynamicCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
61 const SourceRange &OpRange,
62 const SourceRange &DestRange,
64 CXXCastPath &BasePath);
66 static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
67 bool CheckCVR, bool CheckObjCLifetime);
69 // The Try functions attempt a specific way of casting. If they succeed, they
70 // return TC_Success. If their way of casting is not appropriate for the given
71 // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
72 // to emit if no other way succeeds. If their way of casting is appropriate but
73 // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
74 // they emit a specialized diagnostic.
75 // All diagnostics returned by these functions must expect the same three
77 // %0: Cast Type (a value from the CastType enumeration)
79 // %2: Destination Type
80 static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
81 QualType DestType, bool CStyle,
83 CXXCastPath &BasePath,
85 static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
86 QualType DestType, bool CStyle,
87 const SourceRange &OpRange,
90 CXXCastPath &BasePath);
91 static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
92 QualType DestType, bool CStyle,
93 const SourceRange &OpRange,
96 CXXCastPath &BasePath);
97 static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
98 CanQualType DestType, bool CStyle,
99 const SourceRange &OpRange,
100 QualType OrigSrcType,
101 QualType OrigDestType, unsigned &msg,
103 CXXCastPath &BasePath);
104 static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
106 QualType DestType,bool CStyle,
107 const SourceRange &OpRange,
110 CXXCastPath &BasePath);
112 static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
114 Sema::CheckedConversionKind CCK,
115 const SourceRange &OpRange,
118 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
120 Sema::CheckedConversionKind CCK,
121 const SourceRange &OpRange,
124 CXXCastPath &BasePath);
125 static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
126 bool CStyle, unsigned &msg);
127 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
128 QualType DestType, bool CStyle,
129 const SourceRange &OpRange,
134 /// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
136 Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
137 SourceLocation LAngleBracketLoc, Declarator &D,
138 SourceLocation RAngleBracketLoc,
139 SourceLocation LParenLoc, Expr *E,
140 SourceLocation RParenLoc) {
142 assert(!D.isInvalidType());
144 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
145 if (D.isInvalidType())
148 if (getLangOptions().CPlusPlus) {
149 // Check that there are no default arguments (C++ only).
150 CheckExtraCXXDefaultArguments(D);
153 return BuildCXXNamedCast(OpLoc, Kind, TInfo, move(E),
154 SourceRange(LAngleBracketLoc, RAngleBracketLoc),
155 SourceRange(LParenLoc, RParenLoc));
159 Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
160 TypeSourceInfo *DestTInfo, Expr *E,
161 SourceRange AngleBrackets, SourceRange Parens) {
162 ExprResult Ex = Owned(E);
163 QualType DestType = DestTInfo->getType();
165 SourceRange OpRange(OpLoc, Parens.getEnd());
166 SourceRange DestRange = AngleBrackets;
168 // If the type is dependent, we won't do the semantic analysis now.
169 // FIXME: should we check this in a more fine-grained manner?
170 bool TypeDependent = DestType->isDependentType() || Ex.get()->isTypeDependent();
172 ExprValueKind VK = VK_RValue;
174 VK = Expr::getValueKindForType(DestType);
177 default: llvm_unreachable("Unknown C++ cast!");
179 case tok::kw_const_cast:
180 if (!TypeDependent) {
181 CheckConstCast(*this, Ex, DestType, VK, OpRange, DestRange);
185 return Owned(CXXConstCastExpr::Create(Context,
186 DestType.getNonLValueExprType(Context),
187 VK, Ex.take(), DestTInfo, OpLoc,
190 case tok::kw_dynamic_cast: {
191 CastKind Kind = CK_Dependent;
192 CXXCastPath BasePath;
193 if (!TypeDependent) {
194 CheckDynamicCast(*this, Ex, DestType, VK, OpRange, DestRange,
199 return Owned(CXXDynamicCastExpr::Create(Context,
200 DestType.getNonLValueExprType(Context),
201 VK, Kind, Ex.take(), &BasePath, DestTInfo,
202 OpLoc, Parens.getEnd()));
204 case tok::kw_reinterpret_cast: {
205 CastKind Kind = CK_Dependent;
206 if (!TypeDependent) {
207 CheckReinterpretCast(*this, Ex, DestType, VK, OpRange, DestRange, Kind);
211 return Owned(CXXReinterpretCastExpr::Create(Context,
212 DestType.getNonLValueExprType(Context),
213 VK, Kind, Ex.take(), 0,
214 DestTInfo, OpLoc, Parens.getEnd()));
216 case tok::kw_static_cast: {
217 CastKind Kind = CK_Dependent;
218 CXXCastPath BasePath;
219 if (!TypeDependent) {
220 CheckStaticCast(*this, Ex, DestType, VK, OpRange, Kind, BasePath);
225 return Owned(CXXStaticCastExpr::Create(Context,
226 DestType.getNonLValueExprType(Context),
227 VK, Kind, Ex.take(), &BasePath,
228 DestTInfo, OpLoc, Parens.getEnd()));
235 /// Try to diagnose a failed overloaded cast. Returns true if
236 /// diagnostics were emitted.
237 static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
238 SourceRange range, Expr *src,
241 // These cast kinds don't consider user-defined conversions.
254 QualType srcType = src->getType();
255 if (!destType->isRecordType() && !srcType->isRecordType())
258 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
259 InitializationKind initKind
260 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
262 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range)
263 : InitializationKind::CreateCast(/*type range?*/ range);
264 InitializationSequence sequence(S, entity, initKind, &src, 1);
266 assert(sequence.Failed() && "initialization succeeded on second try?");
267 switch (sequence.getFailureKind()) {
268 default: return false;
270 case InitializationSequence::FK_ConstructorOverloadFailed:
271 case InitializationSequence::FK_UserConversionOverloadFailed:
275 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
278 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
280 switch (sequence.getFailedOverloadResult()) {
281 case OR_Success: llvm_unreachable("successful failed overload");
283 case OR_No_Viable_Function:
284 if (candidates.empty())
285 msg = diag::err_ovl_no_conversion_in_cast;
287 msg = diag::err_ovl_no_viable_conversion_in_cast;
288 howManyCandidates = OCD_AllCandidates;
292 msg = diag::err_ovl_ambiguous_conversion_in_cast;
293 howManyCandidates = OCD_ViableCandidates;
297 msg = diag::err_ovl_deleted_conversion_in_cast;
298 howManyCandidates = OCD_ViableCandidates;
302 S.Diag(range.getBegin(), msg)
303 << CT << srcType << destType
304 << range << src->getSourceRange();
306 candidates.NoteCandidates(S, howManyCandidates, &src, 1);
311 /// Diagnose a failed cast.
312 static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
313 SourceRange opRange, Expr *src, QualType destType) {
314 if (src->getType() == S.Context.BoundMemberTy) {
315 (void) S.CheckPlaceholderExpr(src); // will always fail
319 if (msg == diag::err_bad_cxx_cast_generic &&
320 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType))
323 S.Diag(opRange.getBegin(), msg) << castType
324 << src->getType() << destType << opRange << src->getSourceRange();
327 /// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes,
328 /// this removes one level of indirection from both types, provided that they're
329 /// the same kind of pointer (plain or to-member). Unlike the Sema function,
330 /// this one doesn't care if the two pointers-to-member don't point into the
331 /// same class. This is because CastsAwayConstness doesn't care.
332 static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
333 const PointerType *T1PtrType = T1->getAs<PointerType>(),
334 *T2PtrType = T2->getAs<PointerType>();
335 if (T1PtrType && T2PtrType) {
336 T1 = T1PtrType->getPointeeType();
337 T2 = T2PtrType->getPointeeType();
340 const ObjCObjectPointerType *T1ObjCPtrType =
341 T1->getAs<ObjCObjectPointerType>(),
343 T2->getAs<ObjCObjectPointerType>();
346 T1 = T1ObjCPtrType->getPointeeType();
347 T2 = T2ObjCPtrType->getPointeeType();
350 else if (T2PtrType) {
351 T1 = T1ObjCPtrType->getPointeeType();
352 T2 = T2PtrType->getPointeeType();
356 else if (T2ObjCPtrType) {
358 T2 = T2ObjCPtrType->getPointeeType();
359 T1 = T1PtrType->getPointeeType();
364 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(),
365 *T2MPType = T2->getAs<MemberPointerType>();
366 if (T1MPType && T2MPType) {
367 T1 = T1MPType->getPointeeType();
368 T2 = T2MPType->getPointeeType();
372 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(),
373 *T2BPType = T2->getAs<BlockPointerType>();
374 if (T1BPType && T2BPType) {
375 T1 = T1BPType->getPointeeType();
376 T2 = T2BPType->getPointeeType();
383 /// CastsAwayConstness - Check if the pointer conversion from SrcType to
384 /// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by
385 /// the cast checkers. Both arguments must denote pointer (possibly to member)
388 /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
390 /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
392 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
393 bool CheckCVR, bool CheckObjCLifetime) {
394 // If the only checking we care about is for Objective-C lifetime qualifiers,
395 // and we're not in ARC mode, there's nothing to check.
396 if (!CheckCVR && CheckObjCLifetime &&
397 !Self.Context.getLangOptions().ObjCAutoRefCount)
400 // Casting away constness is defined in C++ 5.2.11p8 with reference to
401 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since
402 // the rules are non-trivial. So first we construct Tcv *...cv* as described
404 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
405 SrcType->isBlockPointerType()) &&
406 "Source type is not pointer or pointer to member.");
407 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
408 DestType->isBlockPointerType()) &&
409 "Destination type is not pointer or pointer to member.");
411 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
412 UnwrappedDestType = Self.Context.getCanonicalType(DestType);
413 llvm::SmallVector<Qualifiers, 8> cv1, cv2;
415 // Find the qualifiers. We only care about cvr-qualifiers for the
416 // purpose of this check, because other qualifiers (address spaces,
417 // Objective-C GC, etc.) are part of the type's identity.
418 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) {
419 // Determine the relevant qualifiers at this level.
420 Qualifiers SrcQuals, DestQuals;
421 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
422 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
424 Qualifiers RetainedSrcQuals, RetainedDestQuals;
426 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers());
427 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers());
430 if (CheckObjCLifetime &&
431 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
434 cv1.push_back(RetainedSrcQuals);
435 cv2.push_back(RetainedDestQuals);
440 // Construct void pointers with those qualifiers (in reverse order of
441 // unwrapping, of course).
442 QualType SrcConstruct = Self.Context.VoidTy;
443 QualType DestConstruct = Self.Context.VoidTy;
444 ASTContext &Context = Self.Context;
445 for (llvm::SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(),
447 i1 != cv1.rend(); ++i1, ++i2) {
449 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1));
451 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2));
454 // Test if they're compatible.
455 bool ObjCLifetimeConversion;
456 return SrcConstruct != DestConstruct &&
457 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false,
458 ObjCLifetimeConversion);
461 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
462 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
463 /// checked downcasts in class hierarchies.
465 CheckDynamicCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
466 ExprValueKind &VK, const SourceRange &OpRange,
467 const SourceRange &DestRange, CastKind &Kind,
468 CXXCastPath &BasePath) {
469 QualType OrigDestType = DestType, OrigSrcType = SrcExpr.get()->getType();
470 DestType = Self.Context.getCanonicalType(DestType);
472 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
473 // or "pointer to cv void".
475 QualType DestPointee;
476 const PointerType *DestPointer = DestType->getAs<PointerType>();
477 const ReferenceType *DestReference = 0;
479 DestPointee = DestPointer->getPointeeType();
480 } else if ((DestReference = DestType->getAs<ReferenceType>())) {
481 DestPointee = DestReference->getPointeeType();
482 VK = isa<LValueReferenceType>(DestReference) ? VK_LValue
483 : isa<RValueReferenceType>(DestReference) ? VK_XValue
486 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
487 << OrigDestType << DestRange;
491 const RecordType *DestRecord = DestPointee->getAs<RecordType>();
492 if (DestPointee->isVoidType()) {
493 assert(DestPointer && "Reference to void is not possible");
494 } else if (DestRecord) {
495 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
496 Self.PDiag(diag::err_bad_dynamic_cast_incomplete)
500 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
501 << DestPointee.getUnqualifiedType() << DestRange;
505 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
506 // complete class type, [...]. If T is an lvalue reference type, v shall be
507 // an lvalue of a complete class type, [...]. If T is an rvalue reference
508 // type, v shall be an expression having a complete class type, [...]
509 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
512 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
513 SrcPointee = SrcPointer->getPointeeType();
515 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
516 << OrigSrcType << SrcExpr.get()->getSourceRange();
519 } else if (DestReference->isLValueReferenceType()) {
520 if (!SrcExpr.get()->isLValue()) {
521 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
522 << CT_Dynamic << OrigSrcType << OrigDestType << OpRange;
524 SrcPointee = SrcType;
526 SrcPointee = SrcType;
529 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
531 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
532 Self.PDiag(diag::err_bad_dynamic_cast_incomplete)
533 << SrcExpr.get()->getSourceRange()))
536 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
537 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
541 assert((DestPointer || DestReference) &&
542 "Bad destination non-ptr/ref slipped through.");
543 assert((DestRecord || DestPointee->isVoidType()) &&
544 "Bad destination pointee slipped through.");
545 assert(SrcRecord && "Bad source pointee slipped through.");
547 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
548 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
549 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
550 << CT_Dynamic << OrigSrcType << OrigDestType << OpRange;
554 // C++ 5.2.7p3: If the type of v is the same as the required result type,
556 if (DestRecord == SrcRecord) {
562 // Upcasts are resolved statically.
563 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) {
564 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
565 OpRange.getBegin(), OpRange,
569 Kind = CK_DerivedToBase;
571 // If we are casting to or through a virtual base class, we need a
573 if (Self.BasePathInvolvesVirtualBase(BasePath))
574 Self.MarkVTableUsed(OpRange.getBegin(),
575 cast<CXXRecordDecl>(SrcRecord->getDecl()));
579 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
580 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
581 assert(SrcDecl && "Definition missing");
582 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
583 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
584 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
586 Self.MarkVTableUsed(OpRange.getBegin(),
587 cast<CXXRecordDecl>(SrcRecord->getDecl()));
589 // Done. Everything else is run-time checks.
593 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
594 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
596 /// const char *str = "literal";
597 /// legacy_function(const_cast\<char*\>(str));
599 CheckConstCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, ExprValueKind &VK,
600 const SourceRange &OpRange, const SourceRange &DestRange) {
601 VK = Expr::getValueKindForType(DestType);
602 if (VK == VK_RValue) {
603 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take());
604 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
608 unsigned msg = diag::err_bad_cxx_cast_generic;
609 if (TryConstCast(Self, SrcExpr.get(), DestType, /*CStyle*/false, msg) != TC_Success
611 Self.Diag(OpRange.getBegin(), msg) << CT_Const
612 << SrcExpr.get()->getType() << DestType << OpRange;
615 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
617 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
619 /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
621 CheckReinterpretCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
622 ExprValueKind &VK, const SourceRange &OpRange,
623 const SourceRange &DestRange, CastKind &Kind) {
624 VK = Expr::getValueKindForType(DestType);
625 if (VK == VK_RValue) {
626 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take());
627 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
631 unsigned msg = diag::err_bad_cxx_cast_generic;
633 TryReinterpretCast(Self, SrcExpr, DestType,
634 /*CStyle*/false, OpRange, msg, Kind);
635 if (tcr != TC_Success && msg != 0)
637 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
639 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
640 //FIXME: &f<int>; is overloaded and resolvable
641 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
642 << OverloadExpr::find(SrcExpr.get()).Expression->getName()
643 << DestType << OpRange;
644 Self.NoteAllOverloadCandidates(SrcExpr.get());
647 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), DestType);
649 } else if (tcr == TC_Success && Self.getLangOptions().ObjCAutoRefCount) {
650 Expr *Exp = SrcExpr.get();
651 // Note that Exp does not change with CCK_OtherCast cast type
652 Self.CheckObjCARCConversion(OpRange, DestType,
653 Exp, Sema::CCK_OtherCast);
658 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
659 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
660 /// implicit conversions explicit and getting rid of data loss warnings.
662 CheckStaticCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
663 ExprValueKind &VK, const SourceRange &OpRange,
664 CastKind &Kind, CXXCastPath &BasePath) {
665 // This test is outside everything else because it's the only case where
666 // a non-lvalue-reference target type does not lead to decay.
667 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
668 if (DestType->isVoidType()) {
669 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take());
670 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
672 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
673 ExprResult SingleFunctionExpression =
674 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr.get(),
675 false, // Decay Function to ptr
677 OpRange, DestType, diag::err_bad_static_cast_overload);
678 if (SingleFunctionExpression.isUsable())
680 SrcExpr = SingleFunctionExpression;
689 VK = Expr::getValueKindForType(DestType);
690 if (VK == VK_RValue && !DestType->isRecordType()) {
691 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take());
692 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
696 unsigned msg = diag::err_bad_cxx_cast_generic;
698 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
700 if (tcr != TC_Success && msg != 0) {
701 if (SrcExpr.isInvalid())
703 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
704 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
705 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
706 << oe->getName() << DestType << OpRange
707 << oe->getQualifierLoc().getSourceRange();
708 Self.NoteAllOverloadCandidates(SrcExpr.get());
710 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType);
712 } else if (tcr == TC_Success) {
713 if (Kind == CK_BitCast)
714 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
715 if (Self.getLangOptions().ObjCAutoRefCount) {
716 Expr *Exp = SrcExpr.get();
717 // Note that Exp does not change with CCK_OtherCast cast type
718 Self.CheckObjCARCConversion(OpRange, DestType,
719 Exp, Sema::CCK_OtherCast);
722 else if (Kind == CK_BitCast)
723 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
726 /// TryStaticCast - Check if a static cast can be performed, and do so if
727 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
728 /// and casting away constness.
729 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
731 Sema::CheckedConversionKind CCK,
732 const SourceRange &OpRange, unsigned &msg,
734 CXXCastPath &BasePath) {
735 // Determine whether we have the semantics of a C-style cast.
737 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
739 // The order the tests is not entirely arbitrary. There is one conversion
740 // that can be handled in two different ways. Given:
742 // struct B : public A {
746 // the cast static_cast<const B&>(a) could be seen as either a static
747 // reference downcast, or an explicit invocation of the user-defined
748 // conversion using B's conversion constructor.
749 // DR 427 specifies that the downcast is to be applied here.
751 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
752 // Done outside this function.
756 // C++ 5.2.9p5, reference downcast.
757 // See the function for details.
758 // DR 427 specifies that this is to be applied before paragraph 2.
759 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, OpRange,
760 msg, Kind, BasePath);
761 if (tcr != TC_NotApplicable)
764 // C++0x [expr.static.cast]p3:
765 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
766 // T2" if "cv2 T2" is reference-compatible with "cv1 T1".
767 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, BasePath,
769 if (tcr != TC_NotApplicable)
772 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
773 // [...] if the declaration "T t(e);" is well-formed, [...].
774 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
776 if (SrcExpr.isInvalid())
778 if (tcr != TC_NotApplicable)
781 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
782 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
783 // conversions, subject to further restrictions.
784 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
785 // of qualification conversions impossible.
786 // In the CStyle case, the earlier attempt to const_cast should have taken
787 // care of reverse qualification conversions.
789 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
791 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
792 // converted to an integral type. [...] A value of a scoped enumeration type
793 // can also be explicitly converted to a floating-point type [...].
794 if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
795 if (Enum->getDecl()->isScoped()) {
796 if (DestType->isBooleanType()) {
797 Kind = CK_IntegralToBoolean;
799 } else if (DestType->isIntegralType(Self.Context)) {
800 Kind = CK_IntegralCast;
802 } else if (DestType->isRealFloatingType()) {
803 Kind = CK_IntegralToFloating;
809 // Reverse integral promotion/conversion. All such conversions are themselves
810 // again integral promotions or conversions and are thus already handled by
811 // p2 (TryDirectInitialization above).
812 // (Note: any data loss warnings should be suppressed.)
813 // The exception is the reverse of enum->integer, i.e. integer->enum (and
814 // enum->enum). See also C++ 5.2.9p7.
815 // The same goes for reverse floating point promotion/conversion and
816 // floating-integral conversions. Again, only floating->enum is relevant.
817 if (DestType->isEnumeralType()) {
818 if (SrcType->isComplexType() || SrcType->isVectorType()) {
819 // Fall through - these cannot be converted.
820 } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) {
821 Kind = CK_IntegralCast;
826 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
827 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
828 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
830 if (tcr != TC_NotApplicable)
833 // Reverse member pointer conversion. C++ 4.11 specifies member pointer
834 // conversion. C++ 5.2.9p9 has additional information.
835 // DR54's access restrictions apply here also.
836 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
837 OpRange, msg, Kind, BasePath);
838 if (tcr != TC_NotApplicable)
841 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
842 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
843 // just the usual constness stuff.
844 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
845 QualType SrcPointee = SrcPointer->getPointeeType();
846 if (SrcPointee->isVoidType()) {
847 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
848 QualType DestPointee = DestPointer->getPointeeType();
849 if (DestPointee->isIncompleteOrObjectType()) {
850 // This is definitely the intended conversion, but it might fail due
851 // to a qualifier violation. Note that we permit Objective-C lifetime
852 // and GC qualifier mismatches here.
854 Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
855 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
856 DestPointeeQuals.removeObjCGCAttr();
857 DestPointeeQuals.removeObjCLifetime();
858 SrcPointeeQuals.removeObjCGCAttr();
859 SrcPointeeQuals.removeObjCLifetime();
860 if (DestPointeeQuals != SrcPointeeQuals &&
861 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
862 msg = diag::err_bad_cxx_cast_qualifiers_away;
870 else if (DestType->isObjCObjectPointerType()) {
871 // allow both c-style cast and static_cast of objective-c pointers as
872 // they are pervasive.
873 Kind = CK_AnyPointerToObjCPointerCast;
876 else if (CStyle && DestType->isBlockPointerType()) {
877 // allow c-style cast of void * to block pointers.
878 Kind = CK_AnyPointerToBlockPointerCast;
883 // Allow arbitray objective-c pointer conversion with static casts.
884 if (SrcType->isObjCObjectPointerType() &&
885 DestType->isObjCObjectPointerType()) {
890 // We tried everything. Everything! Nothing works! :-(
891 return TC_NotApplicable;
894 /// Tests whether a conversion according to N2844 is valid.
896 TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType,
897 bool CStyle, CastKind &Kind, CXXCastPath &BasePath,
899 // C++0x [expr.static.cast]p3:
900 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
901 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
902 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
904 return TC_NotApplicable;
906 if (!SrcExpr->isGLValue())
907 return TC_NotApplicable;
909 // Because we try the reference downcast before this function, from now on
910 // this is the only cast possibility, so we issue an error if we fail now.
911 // FIXME: Should allow casting away constness if CStyle.
914 bool ObjCLifetimeConversion;
915 QualType FromType = SrcExpr->getType();
916 QualType ToType = R->getPointeeType();
918 FromType = FromType.getUnqualifiedType();
919 ToType = ToType.getUnqualifiedType();
922 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(),
924 DerivedToBase, ObjCConversion,
925 ObjCLifetimeConversion)
926 < Sema::Ref_Compatible_With_Added_Qualification) {
927 msg = diag::err_bad_lvalue_to_rvalue_cast;
932 Kind = CK_DerivedToBase;
933 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
934 /*DetectVirtual=*/true);
935 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths))
936 return TC_NotApplicable;
938 Self.BuildBasePathArray(Paths, BasePath);
945 /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
947 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
948 bool CStyle, const SourceRange &OpRange,
949 unsigned &msg, CastKind &Kind,
950 CXXCastPath &BasePath) {
951 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
952 // cast to type "reference to cv2 D", where D is a class derived from B,
953 // if a valid standard conversion from "pointer to D" to "pointer to B"
954 // exists, cv2 >= cv1, and B is not a virtual base class of D.
955 // In addition, DR54 clarifies that the base must be accessible in the
956 // current context. Although the wording of DR54 only applies to the pointer
957 // variant of this rule, the intent is clearly for it to apply to the this
958 // conversion as well.
960 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
961 if (!DestReference) {
962 return TC_NotApplicable;
964 bool RValueRef = DestReference->isRValueReferenceType();
965 if (!RValueRef && !SrcExpr->isLValue()) {
966 // We know the left side is an lvalue reference, so we can suggest a reason.
967 msg = diag::err_bad_cxx_cast_rvalue;
968 return TC_NotApplicable;
971 QualType DestPointee = DestReference->getPointeeType();
973 return TryStaticDowncast(Self,
974 Self.Context.getCanonicalType(SrcExpr->getType()),
975 Self.Context.getCanonicalType(DestPointee), CStyle,
976 OpRange, SrcExpr->getType(), DestType, msg, Kind,
980 /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
982 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
983 bool CStyle, const SourceRange &OpRange,
984 unsigned &msg, CastKind &Kind,
985 CXXCastPath &BasePath) {
986 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
987 // type, can be converted to an rvalue of type "pointer to cv2 D", where D
988 // is a class derived from B, if a valid standard conversion from "pointer
989 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
991 // In addition, DR54 clarifies that the base must be accessible in the
994 const PointerType *DestPointer = DestType->getAs<PointerType>();
996 return TC_NotApplicable;
999 const PointerType *SrcPointer = SrcType->getAs<PointerType>();
1001 msg = diag::err_bad_static_cast_pointer_nonpointer;
1002 return TC_NotApplicable;
1005 return TryStaticDowncast(Self,
1006 Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
1007 Self.Context.getCanonicalType(DestPointer->getPointeeType()),
1008 CStyle, OpRange, SrcType, DestType, msg, Kind,
1012 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
1013 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
1014 /// DestType is possible and allowed.
1016 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
1017 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType,
1018 QualType OrigDestType, unsigned &msg,
1019 CastKind &Kind, CXXCastPath &BasePath) {
1020 // We can only work with complete types. But don't complain if it doesn't work
1021 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, Self.PDiag(0)) ||
1022 Self.RequireCompleteType(OpRange.getBegin(), DestType, Self.PDiag(0)))
1023 return TC_NotApplicable;
1025 // Downcast can only happen in class hierarchies, so we need classes.
1026 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
1027 return TC_NotApplicable;
1030 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1031 /*DetectVirtual=*/true);
1032 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) {
1033 return TC_NotApplicable;
1036 // Target type does derive from source type. Now we're serious. If an error
1037 // appears now, it's not ignored.
1038 // This may not be entirely in line with the standard. Take for example:
1040 // struct B : virtual A {
1046 // (void)static_cast<const B&>(*((A*)0));
1048 // As far as the standard is concerned, p5 does not apply (A is virtual), so
1049 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
1050 // However, both GCC and Comeau reject this example, and accepting it would
1051 // mean more complex code if we're to preserve the nice error message.
1052 // FIXME: Being 100% compliant here would be nice to have.
1054 // Must preserve cv, as always, unless we're in C-style mode.
1055 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
1056 msg = diag::err_bad_cxx_cast_qualifiers_away;
1060 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
1061 // This code is analoguous to that in CheckDerivedToBaseConversion, except
1062 // that it builds the paths in reverse order.
1063 // To sum up: record all paths to the base and build a nice string from
1064 // them. Use it to spice up the error message.
1065 if (!Paths.isRecordingPaths()) {
1067 Paths.setRecordingPaths(true);
1068 Self.IsDerivedFrom(DestType, SrcType, Paths);
1070 std::string PathDisplayStr;
1071 std::set<unsigned> DisplayedPaths;
1072 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end();
1074 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) {
1075 // We haven't displayed a path to this particular base
1076 // class subobject yet.
1077 PathDisplayStr += "\n ";
1078 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(),
1081 PathDisplayStr += EI->Base->getType().getAsString() + " -> ";
1082 PathDisplayStr += QualType(DestType).getAsString();
1086 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
1087 << QualType(SrcType).getUnqualifiedType()
1088 << QualType(DestType).getUnqualifiedType()
1089 << PathDisplayStr << OpRange;
1094 if (Paths.getDetectedVirtual() != 0) {
1095 QualType VirtualBase(Paths.getDetectedVirtual(), 0);
1096 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
1097 << OrigSrcType << OrigDestType << VirtualBase << OpRange;
1103 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1106 diag::err_downcast_from_inaccessible_base)) {
1107 case Sema::AR_accessible:
1108 case Sema::AR_delayed: // be optimistic
1109 case Sema::AR_dependent: // be optimistic
1112 case Sema::AR_inaccessible:
1118 Self.BuildBasePathArray(Paths, BasePath);
1119 Kind = CK_BaseToDerived;
1123 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
1124 /// C++ 5.2.9p9 is valid:
1126 /// An rvalue of type "pointer to member of D of type cv1 T" can be
1127 /// converted to an rvalue of type "pointer to member of B of type cv2 T",
1128 /// where B is a base class of D [...].
1131 TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
1132 QualType DestType, bool CStyle,
1133 const SourceRange &OpRange,
1134 unsigned &msg, CastKind &Kind,
1135 CXXCastPath &BasePath) {
1136 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
1138 return TC_NotApplicable;
1140 bool WasOverloadedFunction = false;
1141 DeclAccessPair FoundOverload;
1142 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1143 if (FunctionDecl *Fn
1144 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
1146 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
1147 SrcType = Self.Context.getMemberPointerType(Fn->getType(),
1148 Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
1149 WasOverloadedFunction = true;
1153 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1155 msg = diag::err_bad_static_cast_member_pointer_nonmp;
1156 return TC_NotApplicable;
1159 // T == T, modulo cv
1160 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
1161 DestMemPtr->getPointeeType()))
1162 return TC_NotApplicable;
1165 QualType SrcClass(SrcMemPtr->getClass(), 0);
1166 QualType DestClass(DestMemPtr->getClass(), 0);
1167 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1168 /*DetectVirtual=*/true);
1169 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) {
1170 return TC_NotApplicable;
1173 // B is a base of D. But is it an allowed base? If not, it's a hard error.
1174 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
1176 Paths.setRecordingPaths(true);
1177 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths);
1180 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
1181 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
1182 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
1187 if (const RecordType *VBase = Paths.getDetectedVirtual()) {
1188 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
1189 << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
1195 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1196 DestClass, SrcClass,
1198 diag::err_upcast_to_inaccessible_base)) {
1199 case Sema::AR_accessible:
1200 case Sema::AR_delayed:
1201 case Sema::AR_dependent:
1202 // Optimistically assume that the delayed and dependent cases
1206 case Sema::AR_inaccessible:
1212 if (WasOverloadedFunction) {
1213 // Resolve the address of the overloaded function again, this time
1214 // allowing complaints if something goes wrong.
1215 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
1224 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
1225 if (!SrcExpr.isUsable()) {
1231 Self.BuildBasePathArray(Paths, BasePath);
1232 Kind = CK_DerivedToBaseMemberPointer;
1236 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
1239 /// An expression e can be explicitly converted to a type T using a
1240 /// @c static_cast if the declaration "T t(e);" is well-formed [...].
1242 TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
1243 Sema::CheckedConversionKind CCK,
1244 const SourceRange &OpRange, unsigned &msg,
1246 if (DestType->isRecordType()) {
1247 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1248 diag::err_bad_dynamic_cast_incomplete)) {
1254 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
1255 InitializationKind InitKind
1256 = (CCK == Sema::CCK_CStyleCast)
1257 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange)
1258 : (CCK == Sema::CCK_FunctionalCast)
1259 ? InitializationKind::CreateFunctionalCast(OpRange)
1260 : InitializationKind::CreateCast(OpRange);
1261 Expr *SrcExprRaw = SrcExpr.get();
1262 InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1);
1264 // At this point of CheckStaticCast, if the destination is a reference,
1265 // or the expression is an overload expression this has to work.
1266 // There is no other way that works.
1267 // On the other hand, if we're checking a C-style cast, we've still got
1268 // the reinterpret_cast way.
1270 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
1271 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
1272 return TC_NotApplicable;
1275 = InitSeq.Perform(Self, Entity, InitKind, MultiExprArg(Self, &SrcExprRaw, 1));
1276 if (Result.isInvalid()) {
1281 if (InitSeq.isConstructorInitialization())
1282 Kind = CK_ConstructorConversion;
1286 SrcExpr = move(Result);
1290 /// TryConstCast - See if a const_cast from source to destination is allowed,
1291 /// and perform it if it is.
1292 static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
1293 bool CStyle, unsigned &msg) {
1294 DestType = Self.Context.getCanonicalType(DestType);
1295 QualType SrcType = SrcExpr->getType();
1296 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
1297 if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) {
1298 // Cannot const_cast non-lvalue to lvalue reference type. But if this
1299 // is C-style, static_cast might find a way, so we simply suggest a
1300 // message and tell the parent to keep searching.
1301 msg = diag::err_bad_cxx_cast_rvalue;
1302 return TC_NotApplicable;
1305 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2
1306 // [...] if a pointer to T1 can be [cast] to the type pointer to T2.
1307 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1308 SrcType = Self.Context.getPointerType(SrcType);
1311 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
1312 // the rules for const_cast are the same as those used for pointers.
1314 if (!DestType->isPointerType() &&
1315 !DestType->isMemberPointerType() &&
1316 !DestType->isObjCObjectPointerType()) {
1317 // Cannot cast to non-pointer, non-reference type. Note that, if DestType
1318 // was a reference type, we converted it to a pointer above.
1319 // The status of rvalue references isn't entirely clear, but it looks like
1320 // conversion to them is simply invalid.
1321 // C++ 5.2.11p3: For two pointer types [...]
1323 msg = diag::err_bad_const_cast_dest;
1324 return TC_NotApplicable;
1326 if (DestType->isFunctionPointerType() ||
1327 DestType->isMemberFunctionPointerType()) {
1328 // Cannot cast direct function pointers.
1329 // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
1330 // T is the ultimate pointee of source and target type.
1332 msg = diag::err_bad_const_cast_dest;
1333 return TC_NotApplicable;
1335 SrcType = Self.Context.getCanonicalType(SrcType);
1337 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are
1338 // completely equal.
1339 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers
1340 // in multi-level pointers may change, but the level count must be the same,
1341 // as must be the final pointee type.
1342 while (SrcType != DestType &&
1343 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) {
1344 Qualifiers SrcQuals, DestQuals;
1345 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals);
1346 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals);
1348 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that
1349 // the other qualifiers (e.g., address spaces) are identical.
1350 SrcQuals.removeCVRQualifiers();
1351 DestQuals.removeCVRQualifiers();
1352 if (SrcQuals != DestQuals)
1353 return TC_NotApplicable;
1356 // Since we're dealing in canonical types, the remainder must be the same.
1357 if (SrcType != DestType)
1358 return TC_NotApplicable;
1363 // Checks for undefined behavior in reinterpret_cast.
1364 // The cases that is checked for is:
1365 // *reinterpret_cast<T*>(&a)
1366 // reinterpret_cast<T&>(a)
1367 // where accessing 'a' as type 'T' will result in undefined behavior.
1368 void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
1370 SourceRange Range) {
1371 unsigned DiagID = IsDereference ?
1372 diag::warn_pointer_indirection_from_incompatible_type :
1373 diag::warn_undefined_reinterpret_cast;
1375 if (Diags.getDiagnosticLevel(DiagID, Range.getBegin()) ==
1376 Diagnostic::Ignored) {
1380 QualType SrcTy, DestTy;
1381 if (IsDereference) {
1382 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
1385 SrcTy = SrcType->getPointeeType();
1386 DestTy = DestType->getPointeeType();
1388 if (!DestType->getAs<ReferenceType>()) {
1392 DestTy = DestType->getPointeeType();
1395 // Cast is compatible if the types are the same.
1396 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
1399 // or one of the types is a char or void type
1400 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
1401 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
1404 // or one of the types is a tag type.
1405 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
1409 // FIXME: Scoped enums?
1410 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
1411 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
1412 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
1417 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
1420 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
1421 QualType DestType, bool CStyle,
1422 const SourceRange &OpRange,
1425 bool IsLValueCast = false;
1427 DestType = Self.Context.getCanonicalType(DestType);
1428 QualType SrcType = SrcExpr.get()->getType();
1430 // Is the source an overloaded name? (i.e. &foo)
1431 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ...
1432 if (SrcType == Self.Context.OverloadTy) {
1433 // ... unless foo<int> resolves to an lvalue unambiguously
1434 ExprResult SingleFunctionExpr =
1435 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr.get(),
1436 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr
1438 if (SingleFunctionExpr.isUsable()) {
1439 SrcExpr = move(SingleFunctionExpr);
1440 SrcType = SrcExpr.get()->getType();
1443 return TC_NotApplicable;
1446 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
1447 bool LValue = DestTypeTmp->isLValueReferenceType();
1448 if (LValue && !SrcExpr.get()->isLValue()) {
1449 // Cannot cast non-lvalue to lvalue reference type. See the similar
1450 // comment in const_cast.
1451 msg = diag::err_bad_cxx_cast_rvalue;
1452 return TC_NotApplicable;
1456 Self.CheckCompatibleReinterpretCast(SrcType, DestType,
1457 /*isDereference=*/false, OpRange);
1460 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
1461 // same effect as the conversion *reinterpret_cast<T*>(&x) with the
1462 // built-in & and * operators.
1464 const char *inappropriate = 0;
1465 switch (SrcExpr.get()->getObjectKind()) {
1468 case OK_BitField: inappropriate = "bit-field"; break;
1469 case OK_VectorComponent: inappropriate = "vector element"; break;
1470 case OK_ObjCProperty: inappropriate = "property expression"; break;
1472 if (inappropriate) {
1473 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
1474 << inappropriate << DestType
1475 << OpRange << SrcExpr.get()->getSourceRange();
1476 msg = 0; SrcExpr = ExprError();
1477 return TC_NotApplicable;
1480 // This code does this transformation for the checked types.
1481 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1482 SrcType = Self.Context.getPointerType(SrcType);
1484 IsLValueCast = true;
1487 // Canonicalize source for comparison.
1488 SrcType = Self.Context.getCanonicalType(SrcType);
1490 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
1491 *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1492 if (DestMemPtr && SrcMemPtr) {
1493 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
1494 // can be explicitly converted to an rvalue of type "pointer to member
1495 // of Y of type T2" if T1 and T2 are both function types or both object
1497 if (DestMemPtr->getPointeeType()->isFunctionType() !=
1498 SrcMemPtr->getPointeeType()->isFunctionType())
1499 return TC_NotApplicable;
1501 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
1503 // A reinterpret_cast followed by a const_cast can, though, so in C-style,
1505 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1506 /*CheckObjCLifetime=*/CStyle)) {
1507 msg = diag::err_bad_cxx_cast_qualifiers_away;
1511 // Don't allow casting between member pointers of different sizes.
1512 if (Self.Context.getTypeSize(DestMemPtr) !=
1513 Self.Context.getTypeSize(SrcMemPtr)) {
1514 msg = diag::err_bad_cxx_cast_member_pointer_size;
1518 // A valid member pointer cast.
1519 Kind = IsLValueCast? CK_LValueBitCast : CK_BitCast;
1523 // See below for the enumeral issue.
1524 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
1525 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
1526 // type large enough to hold it. A value of std::nullptr_t can be
1527 // converted to an integral type; the conversion has the same meaning
1528 // and validity as a conversion of (void*)0 to the integral type.
1529 if (Self.Context.getTypeSize(SrcType) >
1530 Self.Context.getTypeSize(DestType)) {
1531 msg = diag::err_bad_reinterpret_cast_small_int;
1534 Kind = CK_PointerToIntegral;
1538 bool destIsVector = DestType->isVectorType();
1539 bool srcIsVector = SrcType->isVectorType();
1540 if (srcIsVector || destIsVector) {
1541 // FIXME: Should this also apply to floating point types?
1542 bool srcIsScalar = SrcType->isIntegralType(Self.Context);
1543 bool destIsScalar = DestType->isIntegralType(Self.Context);
1545 // Check if this is a cast between a vector and something else.
1546 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) &&
1547 !(srcIsVector && destIsVector))
1548 return TC_NotApplicable;
1550 // If both types have the same size, we can successfully cast.
1551 if (Self.Context.getTypeSize(SrcType)
1552 == Self.Context.getTypeSize(DestType)) {
1558 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
1559 else if (srcIsScalar)
1560 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
1562 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
1567 bool destIsPtr = DestType->isAnyPointerType() ||
1568 DestType->isBlockPointerType();
1569 bool srcIsPtr = SrcType->isAnyPointerType() ||
1570 SrcType->isBlockPointerType();
1571 if (!destIsPtr && !srcIsPtr) {
1572 // Except for std::nullptr_t->integer and lvalue->reference, which are
1573 // handled above, at least one of the two arguments must be a pointer.
1574 return TC_NotApplicable;
1577 if (SrcType == DestType) {
1578 // C++ 5.2.10p2 has a note that mentions that, subject to all other
1579 // restrictions, a cast to the same type is allowed. The intent is not
1580 // entirely clear here, since all other paragraphs explicitly forbid casts
1581 // to the same type. However, the behavior of compilers is pretty consistent
1582 // on this point: allow same-type conversion if the involved types are
1583 // pointers, disallow otherwise.
1588 if (DestType->isIntegralType(Self.Context)) {
1589 assert(srcIsPtr && "One type must be a pointer");
1590 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
1591 // type large enough to hold it; except in Microsoft mode, where the
1592 // integral type size doesn't matter.
1593 if ((Self.Context.getTypeSize(SrcType) >
1594 Self.Context.getTypeSize(DestType)) &&
1595 !Self.getLangOptions().Microsoft) {
1596 msg = diag::err_bad_reinterpret_cast_small_int;
1599 Kind = CK_PointerToIntegral;
1603 if (SrcType->isIntegralOrEnumerationType()) {
1604 assert(destIsPtr && "One type must be a pointer");
1605 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
1606 // converted to a pointer.
1607 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
1608 // necessarily converted to a null pointer value.]
1609 Kind = CK_IntegralToPointer;
1613 if (!destIsPtr || !srcIsPtr) {
1614 // With the valid non-pointer conversions out of the way, we can be even
1616 return TC_NotApplicable;
1619 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
1620 // The C-style cast operator can.
1621 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1622 /*CheckObjCLifetime=*/CStyle)) {
1623 msg = diag::err_bad_cxx_cast_qualifiers_away;
1627 // Cannot convert between block pointers and Objective-C object pointers.
1628 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
1629 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
1630 return TC_NotApplicable;
1632 // Any pointer can be cast to an Objective-C pointer type with a C-style
1634 if (CStyle && DestType->isObjCObjectPointerType()) {
1635 Kind = CK_AnyPointerToObjCPointerCast;
1639 // Not casting away constness, so the only remaining check is for compatible
1640 // pointer categories.
1641 Kind = IsLValueCast? CK_LValueBitCast : CK_BitCast;
1643 if (SrcType->isFunctionPointerType()) {
1644 if (DestType->isFunctionPointerType()) {
1645 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
1646 // a pointer to a function of a different type.
1650 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
1651 // an object type or vice versa is conditionally-supported.
1652 // Compilers support it in C++03 too, though, because it's necessary for
1653 // casting the return value of dlsym() and GetProcAddress().
1654 // FIXME: Conditionally-supported behavior should be configurable in the
1655 // TargetInfo or similar.
1656 if (!Self.getLangOptions().CPlusPlus0x)
1657 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange;
1661 if (DestType->isFunctionPointerType()) {
1663 if (!Self.getLangOptions().CPlusPlus0x)
1664 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange;
1668 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
1669 // a pointer to an object of different type.
1670 // Void pointers are not specified, but supported by every compiler out there.
1671 // So we finish by allowing everything that remains - it's got to be two
1677 Sema::CXXCheckCStyleCast(SourceRange R, QualType CastTy, ExprValueKind &VK,
1678 Expr *CastExpr, CastKind &Kind,
1679 CXXCastPath &BasePath,
1680 bool FunctionalStyle) {
1681 // This test is outside everything else because it's the only case where
1682 // a non-lvalue-reference target type does not lead to decay.
1683 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1684 if (CastTy->isVoidType()) {
1687 ExprResult CastExprRes = IgnoredValueConversions(CastExpr);
1688 if (CastExprRes.isInvalid())
1690 CastExpr = CastExprRes.take();
1692 if (CastExpr->getType() == Context.BoundMemberTy)
1693 return CheckPlaceholderExpr(CastExpr); // will always fail
1695 if (CastExpr->getType() == Context.OverloadTy) {
1696 ExprResult SingleFunctionExpr =
1697 ResolveAndFixSingleFunctionTemplateSpecialization(
1698 CastExpr, /* Decay Function to ptr */ false,
1699 /* Complain */ true, R, CastTy,
1700 diag::err_bad_cstyle_cast_overload);
1701 if (SingleFunctionExpr.isInvalid())
1703 CastExpr = SingleFunctionExpr.take();
1706 assert(!CastExpr->getType()->isPlaceholderType());
1708 return Owned(CastExpr);
1711 // Make sure we determine the value kind before we bail out for
1713 VK = Expr::getValueKindForType(CastTy);
1715 // If the type is dependent, we won't do any other semantic analysis now.
1716 if (CastTy->isDependentType() || CastExpr->isTypeDependent()) {
1717 Kind = CK_Dependent;
1718 return Owned(CastExpr);
1721 if (VK == VK_RValue && !CastTy->isRecordType()) {
1722 ExprResult CastExprRes = DefaultFunctionArrayLvalueConversion(CastExpr);
1723 if (CastExprRes.isInvalid())
1725 CastExpr = CastExprRes.take();
1728 // AltiVec vector initialization with a single literal.
1729 if (const VectorType *vecTy = CastTy->getAs<VectorType>())
1730 if (vecTy->getVectorKind() == VectorType::AltiVecVector
1731 && (CastExpr->getType()->isIntegerType()
1732 || CastExpr->getType()->isFloatingType())) {
1733 Kind = CK_VectorSplat;
1734 return Owned(CastExpr);
1737 // C++ [expr.cast]p5: The conversions performed by
1740 // - a static_cast followed by a const_cast,
1741 // - a reinterpret_cast, or
1742 // - a reinterpret_cast followed by a const_cast,
1743 // can be performed using the cast notation of explicit type conversion.
1744 // [...] If a conversion can be interpreted in more than one of the ways
1745 // listed above, the interpretation that appears first in the list is used,
1746 // even if a cast resulting from that interpretation is ill-formed.
1747 // In plain language, this means trying a const_cast ...
1748 unsigned msg = diag::err_bad_cxx_cast_generic;
1749 TryCastResult tcr = TryConstCast(*this, CastExpr, CastTy, /*CStyle*/true,
1751 if (tcr == TC_Success)
1754 Sema::CheckedConversionKind CCK
1755 = FunctionalStyle? Sema::CCK_FunctionalCast
1756 : Sema::CCK_CStyleCast;
1757 if (tcr == TC_NotApplicable) {
1758 // ... or if that is not possible, a static_cast, ignoring const, ...
1759 ExprResult CastExprRes = Owned(CastExpr);
1760 tcr = TryStaticCast(*this, CastExprRes, CastTy, CCK, R, msg, Kind,
1762 if (CastExprRes.isInvalid())
1764 CastExpr = CastExprRes.take();
1765 if (tcr == TC_NotApplicable) {
1766 // ... and finally a reinterpret_cast, ignoring const.
1767 CastExprRes = Owned(CastExpr);
1768 tcr = TryReinterpretCast(*this, CastExprRes, CastTy, /*CStyle*/true, R,
1770 if (CastExprRes.isInvalid())
1772 CastExpr = CastExprRes.take();
1776 if (getLangOptions().ObjCAutoRefCount && tcr == TC_Success)
1777 CheckObjCARCConversion(R, CastTy, CastExpr, CCK);
1779 if (tcr != TC_Success && msg != 0) {
1780 if (CastExpr->getType() == Context.OverloadTy) {
1781 DeclAccessPair Found;
1782 FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(CastExpr,
1784 /* Complain */ true,
1787 assert(!Fn && "cast failed but able to resolve overload expression!!");
1791 diagnoseBadCast(*this, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
1792 R, CastExpr, CastTy);
1795 else if (Kind == CK_BitCast)
1796 CheckCastAlign(CastExpr, CastTy, R);
1798 if (tcr != TC_Success)
1801 return Owned(CastExpr);