//===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file implements semantic analysis for cast expressions, including // 1) C-style casts like '(int) x' // 2) C++ functional casts like 'int(x)' // 3) C++ named casts like 'static_cast(x)' // //===----------------------------------------------------------------------===// #include "clang/AST/ASTContext.h" #include "clang/AST/ASTStructuralEquivalence.h" #include "clang/AST/CXXInheritance.h" #include "clang/AST/ExprCXX.h" #include "clang/AST/ExprObjC.h" #include "clang/AST/RecordLayout.h" #include "clang/Basic/PartialDiagnostic.h" #include "clang/Basic/TargetInfo.h" #include "clang/Lex/Preprocessor.h" #include "clang/Sema/Initialization.h" #include "clang/Sema/SemaInternal.h" #include "llvm/ADT/SmallVector.h" #include using namespace clang; enum TryCastResult { TC_NotApplicable, ///< The cast method is not applicable. TC_Success, ///< The cast method is appropriate and successful. TC_Extension, ///< The cast method is appropriate and accepted as a ///< language extension. TC_Failed ///< The cast method is appropriate, but failed. A ///< diagnostic has been emitted. }; static bool isValidCast(TryCastResult TCR) { return TCR == TC_Success || TCR == TC_Extension; } enum CastType { CT_Const, ///< const_cast CT_Static, ///< static_cast CT_Reinterpret, ///< reinterpret_cast CT_Dynamic, ///< dynamic_cast CT_CStyle, ///< (Type)expr CT_Functional, ///< Type(expr) CT_Addrspace ///< addrspace_cast }; namespace { struct CastOperation { CastOperation(Sema &S, QualType destType, ExprResult src) : Self(S), SrcExpr(src), DestType(destType), ResultType(destType.getNonLValueExprType(S.Context)), ValueKind(Expr::getValueKindForType(destType)), Kind(CK_Dependent), IsARCUnbridgedCast(false) { if (const BuiltinType *placeholder = src.get()->getType()->getAsPlaceholderType()) { PlaceholderKind = placeholder->getKind(); } else { PlaceholderKind = (BuiltinType::Kind) 0; } } Sema &Self; ExprResult SrcExpr; QualType DestType; QualType ResultType; ExprValueKind ValueKind; CastKind Kind; BuiltinType::Kind PlaceholderKind; CXXCastPath BasePath; bool IsARCUnbridgedCast; SourceRange OpRange; SourceRange DestRange; // Top-level semantics-checking routines. void CheckConstCast(); void CheckReinterpretCast(); void CheckStaticCast(); void CheckDynamicCast(); void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization); void CheckCStyleCast(); void CheckBuiltinBitCast(); void CheckAddrspaceCast(); void updatePartOfExplicitCastFlags(CastExpr *CE) { // Walk down from the CE to the OrigSrcExpr, and mark all immediate // ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE // (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched. for (; auto *ICE = dyn_cast(CE->getSubExpr()); CE = ICE) ICE->setIsPartOfExplicitCast(true); } /// Complete an apparently-successful cast operation that yields /// the given expression. ExprResult complete(CastExpr *castExpr) { // If this is an unbridged cast, wrap the result in an implicit // cast that yields the unbridged-cast placeholder type. if (IsARCUnbridgedCast) { castExpr = ImplicitCastExpr::Create( Self.Context, Self.Context.ARCUnbridgedCastTy, CK_Dependent, castExpr, nullptr, castExpr->getValueKind(), Self.CurFPFeatureOverrides()); } updatePartOfExplicitCastFlags(castExpr); return castExpr; } // Internal convenience methods. /// Try to handle the given placeholder expression kind. Return /// true if the source expression has the appropriate placeholder /// kind. A placeholder can only be claimed once. bool claimPlaceholder(BuiltinType::Kind K) { if (PlaceholderKind != K) return false; PlaceholderKind = (BuiltinType::Kind) 0; return true; } bool isPlaceholder() const { return PlaceholderKind != 0; } bool isPlaceholder(BuiltinType::Kind K) const { return PlaceholderKind == K; } // Language specific cast restrictions for address spaces. void checkAddressSpaceCast(QualType SrcType, QualType DestType); void checkCastAlign() { Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange); } void checkObjCConversion(Sema::CheckedConversionKind CCK) { assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()); Expr *src = SrcExpr.get(); if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) == Sema::ACR_unbridged) IsARCUnbridgedCast = true; SrcExpr = src; } /// Check for and handle non-overload placeholder expressions. void checkNonOverloadPlaceholders() { if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload)) return; SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); if (SrcExpr.isInvalid()) return; PlaceholderKind = (BuiltinType::Kind) 0; } }; void CheckNoDeref(Sema &S, const QualType FromType, const QualType ToType, SourceLocation OpLoc) { if (const auto *PtrType = dyn_cast(FromType)) { if (PtrType->getPointeeType()->hasAttr(attr::NoDeref)) { if (const auto *DestType = dyn_cast(ToType)) { if (!DestType->getPointeeType()->hasAttr(attr::NoDeref)) { S.Diag(OpLoc, diag::warn_noderef_to_dereferenceable_pointer); } } } } } struct CheckNoDerefRAII { CheckNoDerefRAII(CastOperation &Op) : Op(Op) {} ~CheckNoDerefRAII() { if (!Op.SrcExpr.isInvalid()) CheckNoDeref(Op.Self, Op.SrcExpr.get()->getType(), Op.ResultType, Op.OpRange.getBegin()); } CastOperation &Op; }; } static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, QualType DestType); // The Try functions attempt a specific way of casting. If they succeed, they // return TC_Success. If their way of casting is not appropriate for the given // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic // to emit if no other way succeeds. If their way of casting is appropriate but // fails, they return TC_Failed and *must* set diag; they can set it to 0 if // they emit a specialized diagnostic. // All diagnostics returned by these functions must expect the same three // arguments: // %0: Cast Type (a value from the CastType enumeration) // %1: Source Type // %2: Destination Type static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, bool CStyle, CastKind &Kind, CXXCastPath &BasePath, unsigned &msg); static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath); static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath); static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, bool CStyle, SourceRange OpRange, QualType OrigSrcType, QualType OrigDestType, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath); static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, QualType DestType,bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath); static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, Sema::CheckedConversionKind CCK, SourceRange OpRange, unsigned &msg, CastKind &Kind, bool ListInitialization); static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, Sema::CheckedConversionKind CCK, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath, bool ListInitialization); static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, unsigned &msg); static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind); static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, unsigned &msg, CastKind &Kind); /// ActOnCXXNamedCast - Parse /// {dynamic,static,reinterpret,const,addrspace}_cast's. ExprResult Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, SourceLocation LAngleBracketLoc, Declarator &D, SourceLocation RAngleBracketLoc, SourceLocation LParenLoc, Expr *E, SourceLocation RParenLoc) { assert(!D.isInvalidType()); TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType()); if (D.isInvalidType()) return ExprError(); if (getLangOpts().CPlusPlus) { // Check that there are no default arguments (C++ only). CheckExtraCXXDefaultArguments(D); } return BuildCXXNamedCast(OpLoc, Kind, TInfo, E, SourceRange(LAngleBracketLoc, RAngleBracketLoc), SourceRange(LParenLoc, RParenLoc)); } ExprResult Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, TypeSourceInfo *DestTInfo, Expr *E, SourceRange AngleBrackets, SourceRange Parens) { ExprResult Ex = E; QualType DestType = DestTInfo->getType(); // If the type is dependent, we won't do the semantic analysis now. bool TypeDependent = DestType->isDependentType() || Ex.get()->isTypeDependent(); CastOperation Op(*this, DestType, E); Op.OpRange = SourceRange(OpLoc, Parens.getEnd()); Op.DestRange = AngleBrackets; switch (Kind) { default: llvm_unreachable("Unknown C++ cast!"); case tok::kw_addrspace_cast: if (!TypeDependent) { Op.CheckAddrspaceCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); } return Op.complete(CXXAddrspaceCastExpr::Create( Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets)); case tok::kw_const_cast: if (!TypeDependent) { Op.CheckConstCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); } return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType, Op.ValueKind, Op.SrcExpr.get(), DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets)); case tok::kw_dynamic_cast: { // dynamic_cast is not supported in C++ for OpenCL. if (getLangOpts().OpenCLCPlusPlus) { return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported) << "dynamic_cast"); } if (!TypeDependent) { Op.CheckDynamicCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); } return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), &Op.BasePath, DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets)); } case tok::kw_reinterpret_cast: { if (!TypeDependent) { Op.CheckReinterpretCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); } return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), nullptr, DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets)); } case tok::kw_static_cast: { if (!TypeDependent) { Op.CheckStaticCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); } return Op.complete(CXXStaticCastExpr::Create( Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), &Op.BasePath, DestTInfo, CurFPFeatureOverrides(), OpLoc, Parens.getEnd(), AngleBrackets)); } } } ExprResult Sema::ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &D, ExprResult Operand, SourceLocation RParenLoc) { assert(!D.isInvalidType()); TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, Operand.get()->getType()); if (D.isInvalidType()) return ExprError(); return BuildBuiltinBitCastExpr(KWLoc, TInfo, Operand.get(), RParenLoc); } ExprResult Sema::BuildBuiltinBitCastExpr(SourceLocation KWLoc, TypeSourceInfo *TSI, Expr *Operand, SourceLocation RParenLoc) { CastOperation Op(*this, TSI->getType(), Operand); Op.OpRange = SourceRange(KWLoc, RParenLoc); TypeLoc TL = TSI->getTypeLoc(); Op.DestRange = SourceRange(TL.getBeginLoc(), TL.getEndLoc()); if (!Operand->isTypeDependent() && !TSI->getType()->isDependentType()) { Op.CheckBuiltinBitCast(); if (Op.SrcExpr.isInvalid()) return ExprError(); } BuiltinBitCastExpr *BCE = new (Context) BuiltinBitCastExpr(Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), TSI, KWLoc, RParenLoc); return Op.complete(BCE); } /// Try to diagnose a failed overloaded cast. Returns true if /// diagnostics were emitted. static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, SourceRange range, Expr *src, QualType destType, bool listInitialization) { switch (CT) { // These cast kinds don't consider user-defined conversions. case CT_Const: case CT_Reinterpret: case CT_Dynamic: case CT_Addrspace: return false; // These do. case CT_Static: case CT_CStyle: case CT_Functional: break; } QualType srcType = src->getType(); if (!destType->isRecordType() && !srcType->isRecordType()) return false; InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); InitializationKind initKind = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), range, listInitialization) : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, listInitialization) : InitializationKind::CreateCast(/*type range?*/ range); InitializationSequence sequence(S, entity, initKind, src); assert(sequence.Failed() && "initialization succeeded on second try?"); switch (sequence.getFailureKind()) { default: return false; case InitializationSequence::FK_ConstructorOverloadFailed: case InitializationSequence::FK_UserConversionOverloadFailed: break; } OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); unsigned msg = 0; OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; switch (sequence.getFailedOverloadResult()) { case OR_Success: llvm_unreachable("successful failed overload"); case OR_No_Viable_Function: if (candidates.empty()) msg = diag::err_ovl_no_conversion_in_cast; else msg = diag::err_ovl_no_viable_conversion_in_cast; howManyCandidates = OCD_AllCandidates; break; case OR_Ambiguous: msg = diag::err_ovl_ambiguous_conversion_in_cast; howManyCandidates = OCD_AmbiguousCandidates; break; case OR_Deleted: msg = diag::err_ovl_deleted_conversion_in_cast; howManyCandidates = OCD_ViableCandidates; break; } candidates.NoteCandidates( PartialDiagnosticAt(range.getBegin(), S.PDiag(msg) << CT << srcType << destType << range << src->getSourceRange()), S, howManyCandidates, src); return true; } /// Diagnose a failed cast. static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, SourceRange opRange, Expr *src, QualType destType, bool listInitialization) { if (msg == diag::err_bad_cxx_cast_generic && tryDiagnoseOverloadedCast(S, castType, opRange, src, destType, listInitialization)) return; S.Diag(opRange.getBegin(), msg) << castType << src->getType() << destType << opRange << src->getSourceRange(); // Detect if both types are (ptr to) class, and note any incompleteness. int DifferentPtrness = 0; QualType From = destType; if (auto Ptr = From->getAs()) { From = Ptr->getPointeeType(); DifferentPtrness++; } QualType To = src->getType(); if (auto Ptr = To->getAs()) { To = Ptr->getPointeeType(); DifferentPtrness--; } if (!DifferentPtrness) { auto RecFrom = From->getAs(); auto RecTo = To->getAs(); if (RecFrom && RecTo) { auto DeclFrom = RecFrom->getAsCXXRecordDecl(); if (!DeclFrom->isCompleteDefinition()) S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) << DeclFrom; auto DeclTo = RecTo->getAsCXXRecordDecl(); if (!DeclTo->isCompleteDefinition()) S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) << DeclTo; } } } namespace { /// The kind of unwrapping we did when determining whether a conversion casts /// away constness. enum CastAwayConstnessKind { /// The conversion does not cast away constness. CACK_None = 0, /// We unwrapped similar types. CACK_Similar = 1, /// We unwrapped dissimilar types with similar representations (eg, a pointer /// versus an Objective-C object pointer). CACK_SimilarKind = 2, /// We unwrapped representationally-unrelated types, such as a pointer versus /// a pointer-to-member. CACK_Incoherent = 3, }; } /// Unwrap one level of types for CastsAwayConstness. /// /// Like Sema::UnwrapSimilarTypes, this removes one level of indirection from /// both types, provided that they're both pointer-like or array-like. Unlike /// the Sema function, doesn't care if the unwrapped pieces are related. /// /// This function may remove additional levels as necessary for correctness: /// the resulting T1 is unwrapped sufficiently that it is never an array type, /// so that its qualifiers can be directly compared to those of T2 (which will /// have the combined set of qualifiers from all indermediate levels of T2), /// as (effectively) required by [expr.const.cast]p7 replacing T1's qualifiers /// with those from T2. static CastAwayConstnessKind unwrapCastAwayConstnessLevel(ASTContext &Context, QualType &T1, QualType &T2) { enum { None, Ptr, MemPtr, BlockPtr, Array }; auto Classify = [](QualType T) { if (T->isAnyPointerType()) return Ptr; if (T->isMemberPointerType()) return MemPtr; if (T->isBlockPointerType()) return BlockPtr; // We somewhat-arbitrarily don't look through VLA types here. This is at // least consistent with the behavior of UnwrapSimilarTypes. if (T->isConstantArrayType() || T->isIncompleteArrayType()) return Array; return None; }; auto Unwrap = [&](QualType T) { if (auto *AT = Context.getAsArrayType(T)) return AT->getElementType(); return T->getPointeeType(); }; CastAwayConstnessKind Kind; if (T2->isReferenceType()) { // Special case: if the destination type is a reference type, unwrap it as // the first level. (The source will have been an lvalue expression in this // case, so there is no corresponding "reference to" in T1 to remove.) This // simulates removing a "pointer to" from both sides. T2 = T2->getPointeeType(); Kind = CastAwayConstnessKind::CACK_Similar; } else if (Context.UnwrapSimilarTypes(T1, T2)) { Kind = CastAwayConstnessKind::CACK_Similar; } else { // Try unwrapping mismatching levels. int T1Class = Classify(T1); if (T1Class == None) return CastAwayConstnessKind::CACK_None; int T2Class = Classify(T2); if (T2Class == None) return CastAwayConstnessKind::CACK_None; T1 = Unwrap(T1); T2 = Unwrap(T2); Kind = T1Class == T2Class ? CastAwayConstnessKind::CACK_SimilarKind : CastAwayConstnessKind::CACK_Incoherent; } // We've unwrapped at least one level. If the resulting T1 is a (possibly // multidimensional) array type, any qualifier on any matching layer of // T2 is considered to correspond to T1. Decompose down to the element // type of T1 so that we can compare properly. while (true) { Context.UnwrapSimilarArrayTypes(T1, T2); if (Classify(T1) != Array) break; auto T2Class = Classify(T2); if (T2Class == None) break; if (T2Class != Array) Kind = CastAwayConstnessKind::CACK_Incoherent; else if (Kind != CastAwayConstnessKind::CACK_Incoherent) Kind = CastAwayConstnessKind::CACK_SimilarKind; T1 = Unwrap(T1); T2 = Unwrap(T2).withCVRQualifiers(T2.getCVRQualifiers()); } return Kind; } /// Check if the pointer conversion from SrcType to DestType casts away /// constness as defined in C++ [expr.const.cast]. This is used by the cast /// checkers. Both arguments must denote pointer (possibly to member) types. /// /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. static CastAwayConstnessKind CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, bool CheckCVR, bool CheckObjCLifetime, QualType *TheOffendingSrcType = nullptr, QualType *TheOffendingDestType = nullptr, Qualifiers *CastAwayQualifiers = nullptr) { // If the only checking we care about is for Objective-C lifetime qualifiers, // and we're not in ObjC mode, there's nothing to check. if (!CheckCVR && CheckObjCLifetime && !Self.Context.getLangOpts().ObjC) return CastAwayConstnessKind::CACK_None; if (!DestType->isReferenceType()) { assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || SrcType->isBlockPointerType()) && "Source type is not pointer or pointer to member."); assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || DestType->isBlockPointerType()) && "Destination type is not pointer or pointer to member."); } QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), UnwrappedDestType = Self.Context.getCanonicalType(DestType); // Find the qualifiers. We only care about cvr-qualifiers for the // purpose of this check, because other qualifiers (address spaces, // Objective-C GC, etc.) are part of the type's identity. QualType PrevUnwrappedSrcType = UnwrappedSrcType; QualType PrevUnwrappedDestType = UnwrappedDestType; auto WorstKind = CastAwayConstnessKind::CACK_Similar; bool AllConstSoFar = true; while (auto Kind = unwrapCastAwayConstnessLevel( Self.Context, UnwrappedSrcType, UnwrappedDestType)) { // Track the worst kind of unwrap we needed to do before we found a // problem. if (Kind > WorstKind) WorstKind = Kind; // Determine the relevant qualifiers at this level. Qualifiers SrcQuals, DestQuals; Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); // We do not meaningfully track object const-ness of Objective-C object // types. Remove const from the source type if either the source or // the destination is an Objective-C object type. if (UnwrappedSrcType->isObjCObjectType() || UnwrappedDestType->isObjCObjectType()) SrcQuals.removeConst(); if (CheckCVR) { Qualifiers SrcCvrQuals = Qualifiers::fromCVRMask(SrcQuals.getCVRQualifiers()); Qualifiers DestCvrQuals = Qualifiers::fromCVRMask(DestQuals.getCVRQualifiers()); if (SrcCvrQuals != DestCvrQuals) { if (CastAwayQualifiers) *CastAwayQualifiers = SrcCvrQuals - DestCvrQuals; // If we removed a cvr-qualifier, this is casting away 'constness'. if (!DestCvrQuals.compatiblyIncludes(SrcCvrQuals)) { if (TheOffendingSrcType) *TheOffendingSrcType = PrevUnwrappedSrcType; if (TheOffendingDestType) *TheOffendingDestType = PrevUnwrappedDestType; return WorstKind; } // If any prior level was not 'const', this is also casting away // 'constness'. We noted the outermost type missing a 'const' already. if (!AllConstSoFar) return WorstKind; } } if (CheckObjCLifetime && !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) return WorstKind; // If we found our first non-const-qualified type, this may be the place // where things start to go wrong. if (AllConstSoFar && !DestQuals.hasConst()) { AllConstSoFar = false; if (TheOffendingSrcType) *TheOffendingSrcType = PrevUnwrappedSrcType; if (TheOffendingDestType) *TheOffendingDestType = PrevUnwrappedDestType; } PrevUnwrappedSrcType = UnwrappedSrcType; PrevUnwrappedDestType = UnwrappedDestType; } return CastAwayConstnessKind::CACK_None; } static TryCastResult getCastAwayConstnessCastKind(CastAwayConstnessKind CACK, unsigned &DiagID) { switch (CACK) { case CastAwayConstnessKind::CACK_None: llvm_unreachable("did not cast away constness"); case CastAwayConstnessKind::CACK_Similar: // FIXME: Accept these as an extension too? case CastAwayConstnessKind::CACK_SimilarKind: DiagID = diag::err_bad_cxx_cast_qualifiers_away; return TC_Failed; case CastAwayConstnessKind::CACK_Incoherent: DiagID = diag::ext_bad_cxx_cast_qualifiers_away_incoherent; return TC_Extension; } llvm_unreachable("unexpected cast away constness kind"); } /// CheckDynamicCast - Check that a dynamic_cast\(SrcExpr) is valid. /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- /// checked downcasts in class hierarchies. void CastOperation::CheckDynamicCast() { CheckNoDerefRAII NoderefCheck(*this); if (ValueKind == VK_RValue) SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); else if (isPlaceholder()) SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); if (SrcExpr.isInvalid()) // if conversion failed, don't report another error return; QualType OrigSrcType = SrcExpr.get()->getType(); QualType DestType = Self.Context.getCanonicalType(this->DestType); // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, // or "pointer to cv void". QualType DestPointee; const PointerType *DestPointer = DestType->getAs(); const ReferenceType *DestReference = nullptr; if (DestPointer) { DestPointee = DestPointer->getPointeeType(); } else if ((DestReference = DestType->getAs())) { DestPointee = DestReference->getPointeeType(); } else { Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) << this->DestType << DestRange; SrcExpr = ExprError(); return; } const RecordType *DestRecord = DestPointee->getAs(); if (DestPointee->isVoidType()) { assert(DestPointer && "Reference to void is not possible"); } else if (DestRecord) { if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, diag::err_bad_cast_incomplete, DestRange)) { SrcExpr = ExprError(); return; } } else { Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) << DestPointee.getUnqualifiedType() << DestRange; SrcExpr = ExprError(); return; } // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to // complete class type, [...]. If T is an lvalue reference type, v shall be // an lvalue of a complete class type, [...]. If T is an rvalue reference // type, v shall be an expression having a complete class type, [...] QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); QualType SrcPointee; if (DestPointer) { if (const PointerType *SrcPointer = SrcType->getAs()) { SrcPointee = SrcPointer->getPointeeType(); } else { Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) << OrigSrcType << this->DestType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } } else if (DestReference->isLValueReferenceType()) { if (!SrcExpr.get()->isLValue()) { Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) << CT_Dynamic << OrigSrcType << this->DestType << OpRange; } SrcPointee = SrcType; } else { // If we're dynamic_casting from a prvalue to an rvalue reference, we need // to materialize the prvalue before we bind the reference to it. if (SrcExpr.get()->isRValue()) SrcExpr = Self.CreateMaterializeTemporaryExpr( SrcType, SrcExpr.get(), /*IsLValueReference*/ false); SrcPointee = SrcType; } const RecordType *SrcRecord = SrcPointee->getAs(); if (SrcRecord) { if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, diag::err_bad_cast_incomplete, SrcExpr.get())) { SrcExpr = ExprError(); return; } } else { Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } assert((DestPointer || DestReference) && "Bad destination non-ptr/ref slipped through."); assert((DestRecord || DestPointee->isVoidType()) && "Bad destination pointee slipped through."); assert(SrcRecord && "Bad source pointee slipped through."); // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) << CT_Dynamic << OrigSrcType << this->DestType << OpRange; SrcExpr = ExprError(); return; } // C++ 5.2.7p3: If the type of v is the same as the required result type, // [except for cv]. if (DestRecord == SrcRecord) { Kind = CK_NoOp; return; } // C++ 5.2.7p5 // Upcasts are resolved statically. if (DestRecord && Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) { if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, OpRange.getBegin(), OpRange, &BasePath)) { SrcExpr = ExprError(); return; } Kind = CK_DerivedToBase; return; } // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); assert(SrcDecl && "Definition missing"); if (!cast(SrcDecl)->isPolymorphic()) { Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); } // dynamic_cast is not available with -fno-rtti. // As an exception, dynamic_cast to void* is available because it doesn't // use RTTI. if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) { Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti); SrcExpr = ExprError(); return; } // Warns when dynamic_cast is used with RTTI data disabled. if (!Self.getLangOpts().RTTIData) { bool MicrosoftABI = Self.getASTContext().getTargetInfo().getCXXABI().isMicrosoft(); bool isClangCL = Self.getDiagnostics().getDiagnosticOptions().getFormat() == DiagnosticOptions::MSVC; if (MicrosoftABI || !DestPointee->isVoidType()) Self.Diag(OpRange.getBegin(), diag::warn_no_dynamic_cast_with_rtti_disabled) << isClangCL; } // Done. Everything else is run-time checks. Kind = CK_Dynamic; } /// CheckConstCast - Check that a const_cast\(SrcExpr) is valid. /// Refer to C++ 5.2.11 for details. const_cast is typically used in code /// like this: /// const char *str = "literal"; /// legacy_function(const_cast\(str)); void CastOperation::CheckConstCast() { CheckNoDerefRAII NoderefCheck(*this); if (ValueKind == VK_RValue) SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); else if (isPlaceholder()) SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); if (SrcExpr.isInvalid()) // if conversion failed, don't report another error return; unsigned msg = diag::err_bad_cxx_cast_generic; auto TCR = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg); if (TCR != TC_Success && msg != 0) { Self.Diag(OpRange.getBegin(), msg) << CT_Const << SrcExpr.get()->getType() << DestType << OpRange; } if (!isValidCast(TCR)) SrcExpr = ExprError(); } void CastOperation::CheckAddrspaceCast() { unsigned msg = diag::err_bad_cxx_cast_generic; auto TCR = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg, Kind); if (TCR != TC_Success && msg != 0) { Self.Diag(OpRange.getBegin(), msg) << CT_Addrspace << SrcExpr.get()->getType() << DestType << OpRange; } if (!isValidCast(TCR)) SrcExpr = ExprError(); } /// Check that a reinterpret_cast\(SrcExpr) is not used as upcast /// or downcast between respective pointers or references. static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr, QualType DestType, SourceRange OpRange) { QualType SrcType = SrcExpr->getType(); // When casting from pointer or reference, get pointee type; use original // type otherwise. const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl(); const CXXRecordDecl *SrcRD = SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl(); // Examining subobjects for records is only possible if the complete and // valid definition is available. Also, template instantiation is not // allowed here. if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl()) return; const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl(); if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl()) return; enum { ReinterpretUpcast, ReinterpretDowncast } ReinterpretKind; CXXBasePaths BasePaths; if (SrcRD->isDerivedFrom(DestRD, BasePaths)) ReinterpretKind = ReinterpretUpcast; else if (DestRD->isDerivedFrom(SrcRD, BasePaths)) ReinterpretKind = ReinterpretDowncast; else return; bool VirtualBase = true; bool NonZeroOffset = false; for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(), E = BasePaths.end(); I != E; ++I) { const CXXBasePath &Path = *I; CharUnits Offset = CharUnits::Zero(); bool IsVirtual = false; for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end(); IElem != EElem; ++IElem) { IsVirtual = IElem->Base->isVirtual(); if (IsVirtual) break; const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl(); assert(BaseRD && "Base type should be a valid unqualified class type"); // Don't check if any base has invalid declaration or has no definition // since it has no layout info. const CXXRecordDecl *Class = IElem->Class, *ClassDefinition = Class->getDefinition(); if (Class->isInvalidDecl() || !ClassDefinition || !ClassDefinition->isCompleteDefinition()) return; const ASTRecordLayout &DerivedLayout = Self.Context.getASTRecordLayout(Class); Offset += DerivedLayout.getBaseClassOffset(BaseRD); } if (!IsVirtual) { // Don't warn if any path is a non-virtually derived base at offset zero. if (Offset.isZero()) return; // Offset makes sense only for non-virtual bases. else NonZeroOffset = true; } VirtualBase = VirtualBase && IsVirtual; } (void) NonZeroOffset; // Silence set but not used warning. assert((VirtualBase || NonZeroOffset) && "Should have returned if has non-virtual base with zero offset"); QualType BaseType = ReinterpretKind == ReinterpretUpcast? DestType : SrcType; QualType DerivedType = ReinterpretKind == ReinterpretUpcast? SrcType : DestType; SourceLocation BeginLoc = OpRange.getBegin(); Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static) << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind) << OpRange; Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static) << int(ReinterpretKind) << FixItHint::CreateReplacement(BeginLoc, "static_cast"); } static bool argTypeIsABIEquivalent(QualType SrcType, QualType DestType, ASTContext &Context) { if (SrcType->isPointerType() && DestType->isPointerType()) return true; // Allow integral type mismatch if their size are equal. if (SrcType->isIntegralType(Context) && DestType->isIntegralType(Context)) if (Context.getTypeInfoInChars(SrcType).Width == Context.getTypeInfoInChars(DestType).Width) return true; return Context.hasSameUnqualifiedType(SrcType, DestType); } static bool checkCastFunctionType(Sema &Self, const ExprResult &SrcExpr, QualType DestType) { if (Self.Diags.isIgnored(diag::warn_cast_function_type, SrcExpr.get()->getExprLoc())) return true; QualType SrcType = SrcExpr.get()->getType(); const FunctionType *SrcFTy = nullptr; const FunctionType *DstFTy = nullptr; if (((SrcType->isBlockPointerType() || SrcType->isFunctionPointerType()) && DestType->isFunctionPointerType()) || (SrcType->isMemberFunctionPointerType() && DestType->isMemberFunctionPointerType())) { SrcFTy = SrcType->getPointeeType()->castAs(); DstFTy = DestType->getPointeeType()->castAs(); } else if (SrcType->isFunctionType() && DestType->isFunctionReferenceType()) { SrcFTy = SrcType->castAs(); DstFTy = DestType.getNonReferenceType()->castAs(); } else { return true; } assert(SrcFTy && DstFTy); auto IsVoidVoid = [](const FunctionType *T) { if (!T->getReturnType()->isVoidType()) return false; if (const auto *PT = T->getAs()) return !PT->isVariadic() && PT->getNumParams() == 0; return false; }; // Skip if either function type is void(*)(void) if (IsVoidVoid(SrcFTy) || IsVoidVoid(DstFTy)) return true; // Check return type. if (!argTypeIsABIEquivalent(SrcFTy->getReturnType(), DstFTy->getReturnType(), Self.Context)) return false; // Check if either has unspecified number of parameters if (SrcFTy->isFunctionNoProtoType() || DstFTy->isFunctionNoProtoType()) return true; // Check parameter types. const auto *SrcFPTy = cast(SrcFTy); const auto *DstFPTy = cast(DstFTy); // In a cast involving function types with a variable argument list only the // types of initial arguments that are provided are considered. unsigned NumParams = SrcFPTy->getNumParams(); unsigned DstNumParams = DstFPTy->getNumParams(); if (NumParams > DstNumParams) { if (!DstFPTy->isVariadic()) return false; NumParams = DstNumParams; } else if (NumParams < DstNumParams) { if (!SrcFPTy->isVariadic()) return false; } for (unsigned i = 0; i < NumParams; ++i) if (!argTypeIsABIEquivalent(SrcFPTy->getParamType(i), DstFPTy->getParamType(i), Self.Context)) return false; return true; } /// CheckReinterpretCast - Check that a reinterpret_cast\(SrcExpr) is /// valid. /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code /// like this: /// char *bytes = reinterpret_cast\(int_ptr); void CastOperation::CheckReinterpretCast() { if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); else checkNonOverloadPlaceholders(); if (SrcExpr.isInvalid()) // if conversion failed, don't report another error return; unsigned msg = diag::err_bad_cxx_cast_generic; TryCastResult tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange, msg, Kind); if (tcr != TC_Success && msg != 0) { if (SrcExpr.isInvalid()) // if conversion failed, don't report another error return; if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { //FIXME: &f; is overloaded and resolvable Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) << OverloadExpr::find(SrcExpr.get()).Expression->getName() << DestType << OpRange; Self.NoteAllOverloadCandidates(SrcExpr.get()); } else { diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), DestType, /*listInitialization=*/false); } } if (isValidCast(tcr)) { if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) checkObjCConversion(Sema::CCK_OtherCast); DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange); if (!checkCastFunctionType(Self, SrcExpr, DestType)) Self.Diag(OpRange.getBegin(), diag::warn_cast_function_type) << SrcExpr.get()->getType() << DestType << OpRange; } else { SrcExpr = ExprError(); } } /// CheckStaticCast - Check that a static_cast\(SrcExpr) is valid. /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making /// implicit conversions explicit and getting rid of data loss warnings. void CastOperation::CheckStaticCast() { CheckNoDerefRAII NoderefCheck(*this); if (isPlaceholder()) { checkNonOverloadPlaceholders(); if (SrcExpr.isInvalid()) return; } if (DestType->getAs() || SrcExpr.get()->getType()->getAs()) { if (Self.CheckMatrixCast(OpRange, DestType, SrcExpr.get()->getType(), Kind)) SrcExpr = ExprError(); return; } // This test is outside everything else because it's the only case where // a non-lvalue-reference target type does not lead to decay. // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". if (DestType->isVoidType()) { Kind = CK_ToVoid; if (claimPlaceholder(BuiltinType::Overload)) { Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, false, // Decay Function to ptr true, // Complain OpRange, DestType, diag::err_bad_static_cast_overload); if (SrcExpr.isInvalid()) return; } SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); return; } if (ValueKind == VK_RValue && !DestType->isRecordType() && !isPlaceholder(BuiltinType::Overload)) { SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); if (SrcExpr.isInvalid()) // if conversion failed, don't report another error return; } unsigned msg = diag::err_bad_cxx_cast_generic; TryCastResult tcr = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, Kind, BasePath, /*ListInitialization=*/false); if (tcr != TC_Success && msg != 0) { if (SrcExpr.isInvalid()) return; if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) << oe->getName() << DestType << OpRange << oe->getQualifierLoc().getSourceRange(); Self.NoteAllOverloadCandidates(SrcExpr.get()); } else { diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType, /*listInitialization=*/false); } } if (isValidCast(tcr)) { if (Kind == CK_BitCast) checkCastAlign(); if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) checkObjCConversion(Sema::CCK_OtherCast); } else { SrcExpr = ExprError(); } } static bool IsAddressSpaceConversion(QualType SrcType, QualType DestType) { auto *SrcPtrType = SrcType->getAs(); if (!SrcPtrType) return false; auto *DestPtrType = DestType->getAs(); if (!DestPtrType) return false; return SrcPtrType->getPointeeType().getAddressSpace() != DestPtrType->getPointeeType().getAddressSpace(); } /// TryStaticCast - Check if a static cast can be performed, and do so if /// possible. If @p CStyle, ignore access restrictions on hierarchy casting /// and casting away constness. static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, Sema::CheckedConversionKind CCK, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath, bool ListInitialization) { // Determine whether we have the semantics of a C-style cast. bool CStyle = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); // The order the tests is not entirely arbitrary. There is one conversion // that can be handled in two different ways. Given: // struct A {}; // struct B : public A { // B(); B(const A&); // }; // const A &a = B(); // the cast static_cast(a) could be seen as either a static // reference downcast, or an explicit invocation of the user-defined // conversion using B's conversion constructor. // DR 427 specifies that the downcast is to be applied here. // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". // Done outside this function. TryCastResult tcr; // C++ 5.2.9p5, reference downcast. // See the function for details. // DR 427 specifies that this is to be applied before paragraph 2. tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, OpRange, msg, Kind, BasePath); if (tcr != TC_NotApplicable) return tcr; // C++11 [expr.static.cast]p3: // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, BasePath, msg); if (tcr != TC_NotApplicable) return tcr; // C++ 5.2.9p2: An expression e can be explicitly converted to a type T // [...] if the declaration "T t(e);" is well-formed, [...]. tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind, ListInitialization); if (SrcExpr.isInvalid()) return TC_Failed; if (tcr != TC_NotApplicable) return tcr; // C++ 5.2.9p6: May apply the reverse of any standard conversion, except // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean // conversions, subject to further restrictions. // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal // of qualification conversions impossible. // In the CStyle case, the earlier attempt to const_cast should have taken // care of reverse qualification conversions. QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly // converted to an integral type. [...] A value of a scoped enumeration type // can also be explicitly converted to a floating-point type [...]. if (const EnumType *Enum = SrcType->getAs()) { if (Enum->getDecl()->isScoped()) { if (DestType->isBooleanType()) { Kind = CK_IntegralToBoolean; return TC_Success; } else if (DestType->isIntegralType(Self.Context)) { Kind = CK_IntegralCast; return TC_Success; } else if (DestType->isRealFloatingType()) { Kind = CK_IntegralToFloating; return TC_Success; } } } // Reverse integral promotion/conversion. All such conversions are themselves // again integral promotions or conversions and are thus already handled by // p2 (TryDirectInitialization above). // (Note: any data loss warnings should be suppressed.) // The exception is the reverse of enum->integer, i.e. integer->enum (and // enum->enum). See also C++ 5.2.9p7. // The same goes for reverse floating point promotion/conversion and // floating-integral conversions. Again, only floating->enum is relevant. if (DestType->isEnumeralType()) { if (Self.RequireCompleteType(OpRange.getBegin(), DestType, diag::err_bad_cast_incomplete)) { SrcExpr = ExprError(); return TC_Failed; } if (SrcType->isIntegralOrEnumerationType()) { // [expr.static.cast]p10 If the enumeration type has a fixed underlying // type, the value is first converted to that type by integral conversion const EnumType *Enum = DestType->getAs(); Kind = Enum->getDecl()->isFixed() && Enum->getDecl()->getIntegerType()->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast; return TC_Success; } else if (SrcType->isRealFloatingType()) { Kind = CK_FloatingToIntegral; return TC_Success; } } // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, Kind, BasePath); if (tcr != TC_NotApplicable) return tcr; // Reverse member pointer conversion. C++ 4.11 specifies member pointer // conversion. C++ 5.2.9p9 has additional information. // DR54's access restrictions apply here also. tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, OpRange, msg, Kind, BasePath); if (tcr != TC_NotApplicable) return tcr; // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to // void*. C++ 5.2.9p10 specifies additional restrictions, which really is // just the usual constness stuff. if (const PointerType *SrcPointer = SrcType->getAs()) { QualType SrcPointee = SrcPointer->getPointeeType(); if (SrcPointee->isVoidType()) { if (const PointerType *DestPointer = DestType->getAs()) { QualType DestPointee = DestPointer->getPointeeType(); if (DestPointee->isIncompleteOrObjectType()) { // This is definitely the intended conversion, but it might fail due // to a qualifier violation. Note that we permit Objective-C lifetime // and GC qualifier mismatches here. if (!CStyle) { Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); DestPointeeQuals.removeObjCGCAttr(); DestPointeeQuals.removeObjCLifetime(); SrcPointeeQuals.removeObjCGCAttr(); SrcPointeeQuals.removeObjCLifetime(); if (DestPointeeQuals != SrcPointeeQuals && !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { msg = diag::err_bad_cxx_cast_qualifiers_away; return TC_Failed; } } Kind = IsAddressSpaceConversion(SrcType, DestType) ? CK_AddressSpaceConversion : CK_BitCast; return TC_Success; } // Microsoft permits static_cast from 'pointer-to-void' to // 'pointer-to-function'. if (!CStyle && Self.getLangOpts().MSVCCompat && DestPointee->isFunctionType()) { Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange; Kind = CK_BitCast; return TC_Success; } } else if (DestType->isObjCObjectPointerType()) { // allow both c-style cast and static_cast of objective-c pointers as // they are pervasive. Kind = CK_CPointerToObjCPointerCast; return TC_Success; } else if (CStyle && DestType->isBlockPointerType()) { // allow c-style cast of void * to block pointers. Kind = CK_AnyPointerToBlockPointerCast; return TC_Success; } } } // Allow arbitrary objective-c pointer conversion with static casts. if (SrcType->isObjCObjectPointerType() && DestType->isObjCObjectPointerType()) { Kind = CK_BitCast; return TC_Success; } // Allow ns-pointer to cf-pointer conversion in either direction // with static casts. if (!CStyle && Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind)) return TC_Success; // See if it looks like the user is trying to convert between // related record types, and select a better diagnostic if so. if (auto SrcPointer = SrcType->getAs()) if (auto DestPointer = DestType->getAs()) if (SrcPointer->getPointeeType()->getAs() && DestPointer->getPointeeType()->getAs()) msg = diag::err_bad_cxx_cast_unrelated_class; // We tried everything. Everything! Nothing works! :-( return TC_NotApplicable; } /// Tests whether a conversion according to N2844 is valid. TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, bool CStyle, CastKind &Kind, CXXCastPath &BasePath, unsigned &msg) { // C++11 [expr.static.cast]p3: // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". const RValueReferenceType *R = DestType->getAs(); if (!R) return TC_NotApplicable; if (!SrcExpr->isGLValue()) return TC_NotApplicable; // Because we try the reference downcast before this function, from now on // this is the only cast possibility, so we issue an error if we fail now. // FIXME: Should allow casting away constness if CStyle. QualType FromType = SrcExpr->getType(); QualType ToType = R->getPointeeType(); if (CStyle) { FromType = FromType.getUnqualifiedType(); ToType = ToType.getUnqualifiedType(); } Sema::ReferenceConversions RefConv; Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( SrcExpr->getBeginLoc(), ToType, FromType, &RefConv); if (RefResult != Sema::Ref_Compatible) { if (CStyle || RefResult == Sema::Ref_Incompatible) return TC_NotApplicable; // Diagnose types which are reference-related but not compatible here since // we can provide better diagnostics. In these cases forwarding to // [expr.static.cast]p4 should never result in a well-formed cast. msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast : diag::err_bad_rvalue_to_rvalue_cast; return TC_Failed; } if (RefConv & Sema::ReferenceConversions::DerivedToBase) { Kind = CK_DerivedToBase; CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, /*DetectVirtual=*/true); if (!Self.IsDerivedFrom(SrcExpr->getBeginLoc(), SrcExpr->getType(), R->getPointeeType(), Paths)) return TC_NotApplicable; Self.BuildBasePathArray(Paths, BasePath); } else Kind = CK_NoOp; return TC_Success; } /// Tests whether a conversion according to C++ 5.2.9p5 is valid. TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath) { // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be // cast to type "reference to cv2 D", where D is a class derived from B, // if a valid standard conversion from "pointer to D" to "pointer to B" // exists, cv2 >= cv1, and B is not a virtual base class of D. // In addition, DR54 clarifies that the base must be accessible in the // current context. Although the wording of DR54 only applies to the pointer // variant of this rule, the intent is clearly for it to apply to the this // conversion as well. const ReferenceType *DestReference = DestType->getAs(); if (!DestReference) { return TC_NotApplicable; } bool RValueRef = DestReference->isRValueReferenceType(); if (!RValueRef && !SrcExpr->isLValue()) { // We know the left side is an lvalue reference, so we can suggest a reason. msg = diag::err_bad_cxx_cast_rvalue; return TC_NotApplicable; } QualType DestPointee = DestReference->getPointeeType(); // FIXME: If the source is a prvalue, we should issue a warning (because the // cast always has undefined behavior), and for AST consistency, we should // materialize a temporary. return TryStaticDowncast(Self, Self.Context.getCanonicalType(SrcExpr->getType()), Self.Context.getCanonicalType(DestPointee), CStyle, OpRange, SrcExpr->getType(), DestType, msg, Kind, BasePath); } /// Tests whether a conversion according to C++ 5.2.9p8 is valid. TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath) { // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class // type, can be converted to an rvalue of type "pointer to cv2 D", where D // is a class derived from B, if a valid standard conversion from "pointer // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base // class of D. // In addition, DR54 clarifies that the base must be accessible in the // current context. const PointerType *DestPointer = DestType->getAs(); if (!DestPointer) { return TC_NotApplicable; } const PointerType *SrcPointer = SrcType->getAs(); if (!SrcPointer) { msg = diag::err_bad_static_cast_pointer_nonpointer; return TC_NotApplicable; } return TryStaticDowncast(Self, Self.Context.getCanonicalType(SrcPointer->getPointeeType()), Self.Context.getCanonicalType(DestPointer->getPointeeType()), CStyle, OpRange, SrcType, DestType, msg, Kind, BasePath); } /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to /// DestType is possible and allowed. TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, bool CStyle, SourceRange OpRange, QualType OrigSrcType, QualType OrigDestType, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath) { // We can only work with complete types. But don't complain if it doesn't work if (!Self.isCompleteType(OpRange.getBegin(), SrcType) || !Self.isCompleteType(OpRange.getBegin(), DestType)) return TC_NotApplicable; // Downcast can only happen in class hierarchies, so we need classes. if (!DestType->getAs() || !SrcType->getAs()) { return TC_NotApplicable; } CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, /*DetectVirtual=*/true); if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) { return TC_NotApplicable; } // Target type does derive from source type. Now we're serious. If an error // appears now, it's not ignored. // This may not be entirely in line with the standard. Take for example: // struct A {}; // struct B : virtual A { // B(A&); // }; // // void f() // { // (void)static_cast(*((A*)0)); // } // As far as the standard is concerned, p5 does not apply (A is virtual), so // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. // However, both GCC and Comeau reject this example, and accepting it would // mean more complex code if we're to preserve the nice error message. // FIXME: Being 100% compliant here would be nice to have. // Must preserve cv, as always, unless we're in C-style mode. if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { msg = diag::err_bad_cxx_cast_qualifiers_away; return TC_Failed; } if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { // This code is analoguous to that in CheckDerivedToBaseConversion, except // that it builds the paths in reverse order. // To sum up: record all paths to the base and build a nice string from // them. Use it to spice up the error message. if (!Paths.isRecordingPaths()) { Paths.clear(); Paths.setRecordingPaths(true); Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths); } std::string PathDisplayStr; std::set DisplayedPaths; for (clang::CXXBasePath &Path : Paths) { if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) { // We haven't displayed a path to this particular base // class subobject yet. PathDisplayStr += "\n "; for (CXXBasePathElement &PE : llvm::reverse(Path)) PathDisplayStr += PE.Base->getType().getAsString() + " -> "; PathDisplayStr += QualType(DestType).getAsString(); } } Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) << QualType(SrcType).getUnqualifiedType() << QualType(DestType).getUnqualifiedType() << PathDisplayStr << OpRange; msg = 0; return TC_Failed; } if (Paths.getDetectedVirtual() != nullptr) { QualType VirtualBase(Paths.getDetectedVirtual(), 0); Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) << OrigSrcType << OrigDestType << VirtualBase << OpRange; msg = 0; return TC_Failed; } if (!CStyle) { switch (Self.CheckBaseClassAccess(OpRange.getBegin(), SrcType, DestType, Paths.front(), diag::err_downcast_from_inaccessible_base)) { case Sema::AR_accessible: case Sema::AR_delayed: // be optimistic case Sema::AR_dependent: // be optimistic break; case Sema::AR_inaccessible: msg = 0; return TC_Failed; } } Self.BuildBasePathArray(Paths, BasePath); Kind = CK_BaseToDerived; return TC_Success; } /// TryStaticMemberPointerUpcast - Tests whether a conversion according to /// C++ 5.2.9p9 is valid: /// /// An rvalue of type "pointer to member of D of type cv1 T" can be /// converted to an rvalue of type "pointer to member of B of type cv2 T", /// where B is a base class of D [...]. /// TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind, CXXCastPath &BasePath) { const MemberPointerType *DestMemPtr = DestType->getAs(); if (!DestMemPtr) return TC_NotApplicable; bool WasOverloadedFunction = false; DeclAccessPair FoundOverload; if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { if (FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, FoundOverload)) { CXXMethodDecl *M = cast(Fn); SrcType = Self.Context.getMemberPointerType(Fn->getType(), Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); WasOverloadedFunction = true; } } const MemberPointerType *SrcMemPtr = SrcType->getAs(); if (!SrcMemPtr) { msg = diag::err_bad_static_cast_member_pointer_nonmp; return TC_NotApplicable; } // Lock down the inheritance model right now in MS ABI, whether or not the // pointee types are the same. if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { (void)Self.isCompleteType(OpRange.getBegin(), SrcType); (void)Self.isCompleteType(OpRange.getBegin(), DestType); } // T == T, modulo cv if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), DestMemPtr->getPointeeType())) return TC_NotApplicable; // B base of D QualType SrcClass(SrcMemPtr->getClass(), 0); QualType DestClass(DestMemPtr->getClass(), 0); CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, /*DetectVirtual=*/true); if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths)) return TC_NotApplicable; // B is a base of D. But is it an allowed base? If not, it's a hard error. if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { Paths.clear(); Paths.setRecordingPaths(true); bool StillOkay = Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths); assert(StillOkay); (void)StillOkay; std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; msg = 0; return TC_Failed; } if (const RecordType *VBase = Paths.getDetectedVirtual()) { Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) << SrcClass << DestClass << QualType(VBase, 0) << OpRange; msg = 0; return TC_Failed; } if (!CStyle) { switch (Self.CheckBaseClassAccess(OpRange.getBegin(), DestClass, SrcClass, Paths.front(), diag::err_upcast_to_inaccessible_base)) { case Sema::AR_accessible: case Sema::AR_delayed: case Sema::AR_dependent: // Optimistically assume that the delayed and dependent cases // will work out. break; case Sema::AR_inaccessible: msg = 0; return TC_Failed; } } if (WasOverloadedFunction) { // Resolve the address of the overloaded function again, this time // allowing complaints if something goes wrong. FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, true, FoundOverload); if (!Fn) { msg = 0; return TC_Failed; } SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); if (!SrcExpr.isUsable()) { msg = 0; return TC_Failed; } } Self.BuildBasePathArray(Paths, BasePath); Kind = CK_DerivedToBaseMemberPointer; return TC_Success; } /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 /// is valid: /// /// An expression e can be explicitly converted to a type T using a /// @c static_cast if the declaration "T t(e);" is well-formed [...]. TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, Sema::CheckedConversionKind CCK, SourceRange OpRange, unsigned &msg, CastKind &Kind, bool ListInitialization) { if (DestType->isRecordType()) { if (Self.RequireCompleteType(OpRange.getBegin(), DestType, diag::err_bad_cast_incomplete) || Self.RequireNonAbstractType(OpRange.getBegin(), DestType, diag::err_allocation_of_abstract_type)) { msg = 0; return TC_Failed; } } InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); InitializationKind InitKind = (CCK == Sema::CCK_CStyleCast) ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, ListInitialization) : (CCK == Sema::CCK_FunctionalCast) ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) : InitializationKind::CreateCast(OpRange); Expr *SrcExprRaw = SrcExpr.get(); // FIXME: Per DR242, we should check for an implicit conversion sequence // or for a constructor that could be invoked by direct-initialization // here, not for an initialization sequence. InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw); // At this point of CheckStaticCast, if the destination is a reference, // or the expression is an overload expression this has to work. // There is no other way that works. // On the other hand, if we're checking a C-style cast, we've still got // the reinterpret_cast way. bool CStyle = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) return TC_NotApplicable; ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw); if (Result.isInvalid()) { msg = 0; return TC_Failed; } if (InitSeq.isConstructorInitialization()) Kind = CK_ConstructorConversion; else Kind = CK_NoOp; SrcExpr = Result; return TC_Success; } /// TryConstCast - See if a const_cast from source to destination is allowed, /// and perform it if it is. static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, unsigned &msg) { DestType = Self.Context.getCanonicalType(DestType); QualType SrcType = SrcExpr.get()->getType(); bool NeedToMaterializeTemporary = false; if (const ReferenceType *DestTypeTmp =DestType->getAs()) { // C++11 5.2.11p4: // if a pointer to T1 can be explicitly converted to the type "pointer to // T2" using a const_cast, then the following conversions can also be // made: // -- an lvalue of type T1 can be explicitly converted to an lvalue of // type T2 using the cast const_cast; // -- a glvalue of type T1 can be explicitly converted to an xvalue of // type T2 using the cast const_cast; and // -- if T1 is a class type, a prvalue of type T1 can be explicitly // converted to an xvalue of type T2 using the cast const_cast. if (isa(DestTypeTmp) && !SrcExpr.get()->isLValue()) { // Cannot const_cast non-lvalue to lvalue reference type. But if this // is C-style, static_cast might find a way, so we simply suggest a // message and tell the parent to keep searching. msg = diag::err_bad_cxx_cast_rvalue; return TC_NotApplicable; } if (isa(DestTypeTmp) && SrcExpr.get()->isRValue()) { if (!SrcType->isRecordType()) { // Cannot const_cast non-class prvalue to rvalue reference type. But if // this is C-style, static_cast can do this. msg = diag::err_bad_cxx_cast_rvalue; return TC_NotApplicable; } // Materialize the class prvalue so that the const_cast can bind a // reference to it. NeedToMaterializeTemporary = true; } // It's not completely clear under the standard whether we can // const_cast bit-field gl-values. Doing so would not be // intrinsically complicated, but for now, we say no for // consistency with other compilers and await the word of the // committee. if (SrcExpr.get()->refersToBitField()) { msg = diag::err_bad_cxx_cast_bitfield; return TC_NotApplicable; } DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); SrcType = Self.Context.getPointerType(SrcType); } // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] // the rules for const_cast are the same as those used for pointers. if (!DestType->isPointerType() && !DestType->isMemberPointerType() && !DestType->isObjCObjectPointerType()) { // Cannot cast to non-pointer, non-reference type. Note that, if DestType // was a reference type, we converted it to a pointer above. // The status of rvalue references isn't entirely clear, but it looks like // conversion to them is simply invalid. // C++ 5.2.11p3: For two pointer types [...] if (!CStyle) msg = diag::err_bad_const_cast_dest; return TC_NotApplicable; } if (DestType->isFunctionPointerType() || DestType->isMemberFunctionPointerType()) { // Cannot cast direct function pointers. // C++ 5.2.11p2: [...] where T is any object type or the void type [...] // T is the ultimate pointee of source and target type. if (!CStyle) msg = diag::err_bad_const_cast_dest; return TC_NotApplicable; } // C++ [expr.const.cast]p3: // "For two similar types T1 and T2, [...]" // // We only allow a const_cast to change cvr-qualifiers, not other kinds of // type qualifiers. (Likewise, we ignore other changes when determining // whether a cast casts away constness.) if (!Self.Context.hasCvrSimilarType(SrcType, DestType)) return TC_NotApplicable; if (NeedToMaterializeTemporary) // This is a const_cast from a class prvalue to an rvalue reference type. // Materialize a temporary to store the result of the conversion. SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(), SrcExpr.get(), /*IsLValueReference*/ false); return TC_Success; } // Checks for undefined behavior in reinterpret_cast. // The cases that is checked for is: // *reinterpret_cast(&a) // reinterpret_cast(a) // where accessing 'a' as type 'T' will result in undefined behavior. void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, bool IsDereference, SourceRange Range) { unsigned DiagID = IsDereference ? diag::warn_pointer_indirection_from_incompatible_type : diag::warn_undefined_reinterpret_cast; if (Diags.isIgnored(DiagID, Range.getBegin())) return; QualType SrcTy, DestTy; if (IsDereference) { if (!SrcType->getAs() || !DestType->getAs()) { return; } SrcTy = SrcType->getPointeeType(); DestTy = DestType->getPointeeType(); } else { if (!DestType->getAs()) { return; } SrcTy = SrcType; DestTy = DestType->getPointeeType(); } // Cast is compatible if the types are the same. if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { return; } // or one of the types is a char or void type if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { return; } // or one of the types is a tag type. if (SrcTy->getAs() || DestTy->getAs()) { return; } // FIXME: Scoped enums? if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { return; } } Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; } static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr, QualType DestType) { QualType SrcType = SrcExpr.get()->getType(); if (Self.Context.hasSameType(SrcType, DestType)) return; if (const PointerType *SrcPtrTy = SrcType->getAs()) if (SrcPtrTy->isObjCSelType()) { QualType DT = DestType; if (isa(DestType)) DT = DestType->getPointeeType(); if (!DT.getUnqualifiedType()->isVoidType()) Self.Diag(SrcExpr.get()->getExprLoc(), diag::warn_cast_pointer_from_sel) << SrcType << DestType << SrcExpr.get()->getSourceRange(); } } /// Diagnose casts that change the calling convention of a pointer to a function /// defined in the current TU. static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr, QualType DstType, SourceRange OpRange) { // Check if this cast would change the calling convention of a function // pointer type. QualType SrcType = SrcExpr.get()->getType(); if (Self.Context.hasSameType(SrcType, DstType) || !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType()) return; const auto *SrcFTy = SrcType->castAs()->getPointeeType()->castAs(); const auto *DstFTy = DstType->castAs()->getPointeeType()->castAs(); CallingConv SrcCC = SrcFTy->getCallConv(); CallingConv DstCC = DstFTy->getCallConv(); if (SrcCC == DstCC) return; // We have a calling convention cast. Check if the source is a pointer to a // known, specific function that has already been defined. Expr *Src = SrcExpr.get()->IgnoreParenImpCasts(); if (auto *UO = dyn_cast(Src)) if (UO->getOpcode() == UO_AddrOf) Src = UO->getSubExpr()->IgnoreParenImpCasts(); auto *DRE = dyn_cast(Src); if (!DRE) return; auto *FD = dyn_cast(DRE->getDecl()); if (!FD) return; // Only warn if we are casting from the default convention to a non-default // convention. This can happen when the programmer forgot to apply the calling // convention to the function declaration and then inserted this cast to // satisfy the type system. CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention( FD->isVariadic(), FD->isCXXInstanceMember()); if (DstCC == DefaultCC || SrcCC != DefaultCC) return; // Diagnose this cast, as it is probably bad. StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC); StringRef DstCCName = FunctionType::getNameForCallConv(DstCC); Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv) << SrcCCName << DstCCName << OpRange; // The checks above are cheaper than checking if the diagnostic is enabled. // However, it's worth checking if the warning is enabled before we construct // a fixit. if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin())) return; // Try to suggest a fixit to change the calling convention of the function // whose address was taken. Try to use the latest macro for the convention. // For example, users probably want to write "WINAPI" instead of "__stdcall" // to match the Windows header declarations. SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc(); Preprocessor &PP = Self.getPreprocessor(); SmallVector AttrTokens; SmallString<64> CCAttrText; llvm::raw_svector_ostream OS(CCAttrText); if (Self.getLangOpts().MicrosoftExt) { // __stdcall or __vectorcall OS << "__" << DstCCName; IdentifierInfo *II = PP.getIdentifierInfo(OS.str()); AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) ? TokenValue(II->getTokenID()) : TokenValue(II)); } else { // __attribute__((stdcall)) or __attribute__((vectorcall)) OS << "__attribute__((" << DstCCName << "))"; AttrTokens.push_back(tok::kw___attribute); AttrTokens.push_back(tok::l_paren); AttrTokens.push_back(tok::l_paren); IdentifierInfo *II = PP.getIdentifierInfo(DstCCName); AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) ? TokenValue(II->getTokenID()) : TokenValue(II)); AttrTokens.push_back(tok::r_paren); AttrTokens.push_back(tok::r_paren); } StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens); if (!AttrSpelling.empty()) CCAttrText = AttrSpelling; OS << ' '; Self.Diag(NameLoc, diag::note_change_calling_conv_fixit) << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText); } static void checkIntToPointerCast(bool CStyle, const SourceRange &OpRange, const Expr *SrcExpr, QualType DestType, Sema &Self) { QualType SrcType = SrcExpr->getType(); // Not warning on reinterpret_cast, boolean, constant expressions, etc // are not explicit design choices, but consistent with GCC's behavior. // Feel free to modify them if you've reason/evidence for an alternative. if (CStyle && SrcType->isIntegralType(Self.Context) && !SrcType->isBooleanType() && !SrcType->isEnumeralType() && !SrcExpr->isIntegerConstantExpr(Self.Context) && Self.Context.getTypeSize(DestType) > Self.Context.getTypeSize(SrcType)) { // Separate between casts to void* and non-void* pointers. // Some APIs use (abuse) void* for something like a user context, // and often that value is an integer even if it isn't a pointer itself. // Having a separate warning flag allows users to control the warning // for their workflow. unsigned Diag = DestType->isVoidPointerType() ? diag::warn_int_to_void_pointer_cast : diag::warn_int_to_pointer_cast; Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange; } } static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType, ExprResult &Result) { // We can only fix an overloaded reinterpret_cast if // - it is a template with explicit arguments that resolves to an lvalue // unambiguously, or // - it is the only function in an overload set that may have its address // taken. Expr *E = Result.get(); // TODO: what if this fails because of DiagnoseUseOfDecl or something // like it? if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( Result, Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr ) && Result.isUsable()) return true; // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization // preserves Result. Result = E; if (!Self.resolveAndFixAddressOfSingleOverloadCandidate( Result, /*DoFunctionPointerConversion=*/true)) return false; return Result.isUsable(); } static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, SourceRange OpRange, unsigned &msg, CastKind &Kind) { bool IsLValueCast = false; DestType = Self.Context.getCanonicalType(DestType); QualType SrcType = SrcExpr.get()->getType(); // Is the source an overloaded name? (i.e. &foo) // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5) if (SrcType == Self.Context.OverloadTy) { ExprResult FixedExpr = SrcExpr; if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr)) return TC_NotApplicable; assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr"); SrcExpr = FixedExpr; SrcType = SrcExpr.get()->getType(); } if (const ReferenceType *DestTypeTmp = DestType->getAs()) { if (!SrcExpr.get()->isGLValue()) { // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the // similar comment in const_cast. msg = diag::err_bad_cxx_cast_rvalue; return TC_NotApplicable; } if (!CStyle) { Self.CheckCompatibleReinterpretCast(SrcType, DestType, /*IsDereference=*/false, OpRange); } // C++ 5.2.10p10: [...] a reference cast reinterpret_cast(x) has the // same effect as the conversion *reinterpret_cast(&x) with the // built-in & and * operators. const char *inappropriate = nullptr; switch (SrcExpr.get()->getObjectKind()) { case OK_Ordinary: break; case OK_BitField: msg = diag::err_bad_cxx_cast_bitfield; return TC_NotApplicable; // FIXME: Use a specific diagnostic for the rest of these cases. case OK_VectorComponent: inappropriate = "vector element"; break; case OK_MatrixComponent: inappropriate = "matrix element"; break; case OK_ObjCProperty: inappropriate = "property expression"; break; case OK_ObjCSubscript: inappropriate = "container subscripting expression"; break; } if (inappropriate) { Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) << inappropriate << DestType << OpRange << SrcExpr.get()->getSourceRange(); msg = 0; SrcExpr = ExprError(); return TC_NotApplicable; } // This code does this transformation for the checked types. DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); SrcType = Self.Context.getPointerType(SrcType); IsLValueCast = true; } // Canonicalize source for comparison. SrcType = Self.Context.getCanonicalType(SrcType); const MemberPointerType *DestMemPtr = DestType->getAs(), *SrcMemPtr = SrcType->getAs(); if (DestMemPtr && SrcMemPtr) { // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" // can be explicitly converted to an rvalue of type "pointer to member // of Y of type T2" if T1 and T2 are both function types or both object // types. if (DestMemPtr->isMemberFunctionPointer() != SrcMemPtr->isMemberFunctionPointer()) return TC_NotApplicable; if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { // We need to determine the inheritance model that the class will use if // haven't yet. (void)Self.isCompleteType(OpRange.getBegin(), SrcType); (void)Self.isCompleteType(OpRange.getBegin(), DestType); } // Don't allow casting between member pointers of different sizes. if (Self.Context.getTypeSize(DestMemPtr) != Self.Context.getTypeSize(SrcMemPtr)) { msg = diag::err_bad_cxx_cast_member_pointer_size; return TC_Failed; } // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away // constness. // A reinterpret_cast followed by a const_cast can, though, so in C-style, // we accept it. if (auto CACK = CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, /*CheckObjCLifetime=*/CStyle)) return getCastAwayConstnessCastKind(CACK, msg); // A valid member pointer cast. assert(!IsLValueCast); Kind = CK_ReinterpretMemberPointer; return TC_Success; } // See below for the enumeral issue. if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral // type large enough to hold it. A value of std::nullptr_t can be // converted to an integral type; the conversion has the same meaning // and validity as a conversion of (void*)0 to the integral type. if (Self.Context.getTypeSize(SrcType) > Self.Context.getTypeSize(DestType)) { msg = diag::err_bad_reinterpret_cast_small_int; return TC_Failed; } Kind = CK_PointerToIntegral; return TC_Success; } // Allow reinterpret_casts between vectors of the same size and // between vectors and integers of the same size. bool destIsVector = DestType->isVectorType(); bool srcIsVector = SrcType->isVectorType(); if (srcIsVector || destIsVector) { // Allow bitcasting between SVE VLATs and VLSTs, and vice-versa. if (Self.isValidSveBitcast(SrcType, DestType)) { Kind = CK_BitCast; return TC_Success; } // The non-vector type, if any, must have integral type. This is // the same rule that C vector casts use; note, however, that enum // types are not integral in C++. if ((!destIsVector && !DestType->isIntegralType(Self.Context)) || (!srcIsVector && !SrcType->isIntegralType(Self.Context))) return TC_NotApplicable; // The size we want to consider is eltCount * eltSize. // That's exactly what the lax-conversion rules will check. if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) { Kind = CK_BitCast; return TC_Success; } if (Self.LangOpts.OpenCL && !CStyle) { if (DestType->isExtVectorType() || SrcType->isExtVectorType()) { // FIXME: Allow for reinterpret cast between 3 and 4 element vectors if (Self.areVectorTypesSameSize(SrcType, DestType)) { Kind = CK_BitCast; return TC_Success; } } } // Otherwise, pick a reasonable diagnostic. if (!destIsVector) msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; else if (!srcIsVector) msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; else msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; return TC_Failed; } if (SrcType == DestType) { // C++ 5.2.10p2 has a note that mentions that, subject to all other // restrictions, a cast to the same type is allowed so long as it does not // cast away constness. In C++98, the intent was not entirely clear here, // since all other paragraphs explicitly forbid casts to the same type. // C++11 clarifies this case with p2. // // The only allowed types are: integral, enumeration, pointer, or // pointer-to-member types. We also won't restrict Obj-C pointers either. Kind = CK_NoOp; TryCastResult Result = TC_NotApplicable; if (SrcType->isIntegralOrEnumerationType() || SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || SrcType->isBlockPointerType()) { Result = TC_Success; } return Result; } bool destIsPtr = DestType->isAnyPointerType() || DestType->isBlockPointerType(); bool srcIsPtr = SrcType->isAnyPointerType() || SrcType->isBlockPointerType(); if (!destIsPtr && !srcIsPtr) { // Except for std::nullptr_t->integer and lvalue->reference, which are // handled above, at least one of the two arguments must be a pointer. return TC_NotApplicable; } if (DestType->isIntegralType(Self.Context)) { assert(srcIsPtr && "One type must be a pointer"); // C++ 5.2.10p4: A pointer can be explicitly converted to any integral // type large enough to hold it; except in Microsoft mode, where the // integral type size doesn't matter (except we don't allow bool). if ((Self.Context.getTypeSize(SrcType) > Self.Context.getTypeSize(DestType))) { bool MicrosoftException = Self.getLangOpts().MicrosoftExt && !DestType->isBooleanType(); if (MicrosoftException) { unsigned Diag = SrcType->isVoidPointerType() ? diag::warn_void_pointer_to_int_cast : diag::warn_pointer_to_int_cast; Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange; } else { msg = diag::err_bad_reinterpret_cast_small_int; return TC_Failed; } } Kind = CK_PointerToIntegral; return TC_Success; } if (SrcType->isIntegralOrEnumerationType()) { assert(destIsPtr && "One type must be a pointer"); checkIntToPointerCast(CStyle, OpRange, SrcExpr.get(), DestType, Self); // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly // converted to a pointer. // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not // necessarily converted to a null pointer value.] Kind = CK_IntegralToPointer; return TC_Success; } if (!destIsPtr || !srcIsPtr) { // With the valid non-pointer conversions out of the way, we can be even // more stringent. return TC_NotApplicable; } // Cannot convert between block pointers and Objective-C object pointers. if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) return TC_NotApplicable; // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. // The C-style cast operator can. TryCastResult SuccessResult = TC_Success; if (auto CACK = CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, /*CheckObjCLifetime=*/CStyle)) SuccessResult = getCastAwayConstnessCastKind(CACK, msg); if (IsAddressSpaceConversion(SrcType, DestType)) { Kind = CK_AddressSpaceConversion; assert(SrcType->isPointerType() && DestType->isPointerType()); if (!CStyle && !DestType->getPointeeType().getQualifiers().isAddressSpaceSupersetOf( SrcType->getPointeeType().getQualifiers())) { SuccessResult = TC_Failed; } } else if (IsLValueCast) { Kind = CK_LValueBitCast; } else if (DestType->isObjCObjectPointerType()) { Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); } else if (DestType->isBlockPointerType()) { if (!SrcType->isBlockPointerType()) { Kind = CK_AnyPointerToBlockPointerCast; } else { Kind = CK_BitCast; } } else { Kind = CK_BitCast; } // Any pointer can be cast to an Objective-C pointer type with a C-style // cast. if (CStyle && DestType->isObjCObjectPointerType()) { return SuccessResult; } if (CStyle) DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); // Not casting away constness, so the only remaining check is for compatible // pointer categories. if (SrcType->isFunctionPointerType()) { if (DestType->isFunctionPointerType()) { // C++ 5.2.10p6: A pointer to a function can be explicitly converted to // a pointer to a function of a different type. return SuccessResult; } // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to // an object type or vice versa is conditionally-supported. // Compilers support it in C++03 too, though, because it's necessary for // casting the return value of dlsym() and GetProcAddress(). // FIXME: Conditionally-supported behavior should be configurable in the // TargetInfo or similar. Self.Diag(OpRange.getBegin(), Self.getLangOpts().CPlusPlus11 ? diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) << OpRange; return SuccessResult; } if (DestType->isFunctionPointerType()) { // See above. Self.Diag(OpRange.getBegin(), Self.getLangOpts().CPlusPlus11 ? diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) << OpRange; return SuccessResult; } // Diagnose address space conversion in nested pointers. QualType DestPtee = DestType->getPointeeType().isNull() ? DestType->getPointeeType() : DestType->getPointeeType()->getPointeeType(); QualType SrcPtee = SrcType->getPointeeType().isNull() ? SrcType->getPointeeType() : SrcType->getPointeeType()->getPointeeType(); while (!DestPtee.isNull() && !SrcPtee.isNull()) { if (DestPtee.getAddressSpace() != SrcPtee.getAddressSpace()) { Self.Diag(OpRange.getBegin(), diag::warn_bad_cxx_cast_nested_pointer_addr_space) << CStyle << SrcType << DestType << SrcExpr.get()->getSourceRange(); break; } DestPtee = DestPtee->getPointeeType(); SrcPtee = SrcPtee->getPointeeType(); } // C++ 5.2.10p7: A pointer to an object can be explicitly converted to // a pointer to an object of different type. // Void pointers are not specified, but supported by every compiler out there. // So we finish by allowing everything that remains - it's got to be two // object pointers. return SuccessResult; } static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, bool CStyle, unsigned &msg, CastKind &Kind) { if (!Self.getLangOpts().OpenCL) // FIXME: As compiler doesn't have any information about overlapping addr // spaces at the moment we have to be permissive here. return TC_NotApplicable; // Even though the logic below is general enough and can be applied to // non-OpenCL mode too, we fast-path above because no other languages // define overlapping address spaces currently. auto SrcType = SrcExpr.get()->getType(); // FIXME: Should this be generalized to references? The reference parameter // however becomes a reference pointee type here and therefore rejected. // Perhaps this is the right behavior though according to C++. auto SrcPtrType = SrcType->getAs(); if (!SrcPtrType) return TC_NotApplicable; auto DestPtrType = DestType->getAs(); if (!DestPtrType) return TC_NotApplicable; auto SrcPointeeType = SrcPtrType->getPointeeType(); auto DestPointeeType = DestPtrType->getPointeeType(); if (!DestPointeeType.isAddressSpaceOverlapping(SrcPointeeType)) { msg = diag::err_bad_cxx_cast_addr_space_mismatch; return TC_Failed; } auto SrcPointeeTypeWithoutAS = Self.Context.removeAddrSpaceQualType(SrcPointeeType.getCanonicalType()); auto DestPointeeTypeWithoutAS = Self.Context.removeAddrSpaceQualType(DestPointeeType.getCanonicalType()); if (Self.Context.hasSameType(SrcPointeeTypeWithoutAS, DestPointeeTypeWithoutAS)) { Kind = SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace() ? CK_NoOp : CK_AddressSpaceConversion; return TC_Success; } else { return TC_NotApplicable; } } void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) { // In OpenCL only conversions between pointers to objects in overlapping // addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps // with any named one, except for constant. // Converting the top level pointee addrspace is permitted for compatible // addrspaces (such as 'generic int *' to 'local int *' or vice versa), but // if any of the nested pointee addrspaces differ, we emit a warning // regardless of addrspace compatibility. This makes // local int ** p; // return (generic int **) p; // warn even though local -> generic is permitted. if (Self.getLangOpts().OpenCL) { const Type *DestPtr, *SrcPtr; bool Nested = false; unsigned DiagID = diag::err_typecheck_incompatible_address_space; DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()), SrcPtr = Self.getASTContext().getCanonicalType(SrcType.getTypePtr()); while (isa(DestPtr) && isa(SrcPtr)) { const PointerType *DestPPtr = cast(DestPtr); const PointerType *SrcPPtr = cast(SrcPtr); QualType DestPPointee = DestPPtr->getPointeeType(); QualType SrcPPointee = SrcPPtr->getPointeeType(); if (Nested ? DestPPointee.getAddressSpace() != SrcPPointee.getAddressSpace() : !DestPPointee.isAddressSpaceOverlapping(SrcPPointee)) { Self.Diag(OpRange.getBegin(), DiagID) << SrcType << DestType << Sema::AA_Casting << SrcExpr.get()->getSourceRange(); if (!Nested) SrcExpr = ExprError(); return; } DestPtr = DestPPtr->getPointeeType().getTypePtr(); SrcPtr = SrcPPtr->getPointeeType().getTypePtr(); Nested = true; DiagID = diag::ext_nested_pointer_qualifier_mismatch; } } } void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, bool ListInitialization) { assert(Self.getLangOpts().CPlusPlus); // Handle placeholders. if (isPlaceholder()) { // C-style casts can resolve __unknown_any types. if (claimPlaceholder(BuiltinType::UnknownAny)) { SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, SrcExpr.get(), Kind, ValueKind, BasePath); return; } checkNonOverloadPlaceholders(); if (SrcExpr.isInvalid()) return; } // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". // This test is outside everything else because it's the only case where // a non-lvalue-reference target type does not lead to decay. if (DestType->isVoidType()) { Kind = CK_ToVoid; if (claimPlaceholder(BuiltinType::Overload)) { Self.ResolveAndFixSingleFunctionTemplateSpecialization( SrcExpr, /* Decay Function to ptr */ false, /* Complain */ true, DestRange, DestType, diag::err_bad_cstyle_cast_overload); if (SrcExpr.isInvalid()) return; } SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); return; } // If the type is dependent, we won't do any other semantic analysis now. if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() || SrcExpr.get()->isValueDependent()) { assert(Kind == CK_Dependent); return; } if (ValueKind == VK_RValue && !DestType->isRecordType() && !isPlaceholder(BuiltinType::Overload)) { SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); if (SrcExpr.isInvalid()) return; } if (DestType->getAs() || SrcExpr.get()->getType()->getAs()) { if (Self.CheckMatrixCast(OpRange, DestType, SrcExpr.get()->getType(), Kind)) SrcExpr = ExprError(); return; } // AltiVec vector initialization with a single literal. if (const VectorType *vecTy = DestType->getAs()) if (vecTy->getVectorKind() == VectorType::AltiVecVector && (SrcExpr.get()->getType()->isIntegerType() || SrcExpr.get()->getType()->isFloatingType())) { Kind = CK_VectorSplat; SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); return; } // C++ [expr.cast]p5: The conversions performed by // - a const_cast, // - a static_cast, // - a static_cast followed by a const_cast, // - a reinterpret_cast, or // - a reinterpret_cast followed by a const_cast, // can be performed using the cast notation of explicit type conversion. // [...] If a conversion can be interpreted in more than one of the ways // listed above, the interpretation that appears first in the list is used, // even if a cast resulting from that interpretation is ill-formed. // In plain language, this means trying a const_cast ... // Note that for address space we check compatibility after const_cast. unsigned msg = diag::err_bad_cxx_cast_generic; TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg); if (SrcExpr.isInvalid()) return; if (isValidCast(tcr)) Kind = CK_NoOp; Sema::CheckedConversionKind CCK = FunctionalStyle ? Sema::CCK_FunctionalCast : Sema::CCK_CStyleCast; if (tcr == TC_NotApplicable) { tcr = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg, Kind); if (SrcExpr.isInvalid()) return; if (tcr == TC_NotApplicable) { // ... or if that is not possible, a static_cast, ignoring const and // addr space, ... tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind, BasePath, ListInitialization); if (SrcExpr.isInvalid()) return; if (tcr == TC_NotApplicable) { // ... and finally a reinterpret_cast, ignoring const and addr space. tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/ true, OpRange, msg, Kind); if (SrcExpr.isInvalid()) return; } } } if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() && isValidCast(tcr)) checkObjCConversion(CCK); if (tcr != TC_Success && msg != 0) { if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { DeclAccessPair Found; FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, /*Complain*/ true, Found); if (Fn) { // If DestType is a function type (not to be confused with the function // pointer type), it will be possible to resolve the function address, // but the type cast should be considered as failure. OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression; Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload) << OE->getName() << DestType << OpRange << OE->getQualifierLoc().getSourceRange(); Self.NoteAllOverloadCandidates(SrcExpr.get()); } } else { diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), OpRange, SrcExpr.get(), DestType, ListInitialization); } } if (isValidCast(tcr)) { if (Kind == CK_BitCast) checkCastAlign(); if (!checkCastFunctionType(Self, SrcExpr, DestType)) Self.Diag(OpRange.getBegin(), diag::warn_cast_function_type) << SrcExpr.get()->getType() << DestType << OpRange; } else { SrcExpr = ExprError(); } } /// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a /// non-matching type. Such as enum function call to int, int call to /// pointer; etc. Cast to 'void' is an exception. static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr, QualType DestType) { if (Self.Diags.isIgnored(diag::warn_bad_function_cast, SrcExpr.get()->getExprLoc())) return; if (!isa(SrcExpr.get())) return; QualType SrcType = SrcExpr.get()->getType(); if (DestType.getUnqualifiedType()->isVoidType()) return; if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType()) && (DestType->isAnyPointerType() || DestType->isBlockPointerType())) return; if (SrcType->isIntegerType() && DestType->isIntegerType() && (SrcType->isBooleanType() == DestType->isBooleanType()) && (SrcType->isEnumeralType() == DestType->isEnumeralType())) return; if (SrcType->isRealFloatingType() && DestType->isRealFloatingType()) return; if (SrcType->isEnumeralType() && DestType->isEnumeralType()) return; if (SrcType->isComplexType() && DestType->isComplexType()) return; if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType()) return; if (SrcType->isFixedPointType() && DestType->isFixedPointType()) return; Self.Diag(SrcExpr.get()->getExprLoc(), diag::warn_bad_function_cast) << SrcType << DestType << SrcExpr.get()->getSourceRange(); } /// Check the semantics of a C-style cast operation, in C. void CastOperation::CheckCStyleCast() { assert(!Self.getLangOpts().CPlusPlus); // C-style casts can resolve __unknown_any types. if (claimPlaceholder(BuiltinType::UnknownAny)) { SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, SrcExpr.get(), Kind, ValueKind, BasePath); return; } // C99 6.5.4p2: the cast type needs to be void or scalar and the expression // type needs to be scalar. if (DestType->isVoidType()) { // We don't necessarily do lvalue-to-rvalue conversions on this. SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); if (SrcExpr.isInvalid()) return; // Cast to void allows any expr type. Kind = CK_ToVoid; return; } // If the type is dependent, we won't do any other semantic analysis now. if (Self.getASTContext().isDependenceAllowed() && (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() || SrcExpr.get()->isValueDependent())) { assert((DestType->containsErrors() || SrcExpr.get()->containsErrors() || SrcExpr.get()->containsErrors()) && "should only occur in error-recovery path."); assert(Kind == CK_Dependent); return; } // Overloads are allowed with C extensions, so we need to support them. if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { DeclAccessPair DAP; if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction( SrcExpr.get(), DestType, /*Complain=*/true, DAP)) SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD); else return; assert(SrcExpr.isUsable()); } SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); if (SrcExpr.isInvalid()) return; QualType SrcType = SrcExpr.get()->getType(); assert(!SrcType->isPlaceholderType()); checkAddressSpaceCast(SrcType, DestType); if (SrcExpr.isInvalid()) return; if (Self.RequireCompleteType(OpRange.getBegin(), DestType, diag::err_typecheck_cast_to_incomplete)) { SrcExpr = ExprError(); return; } // Allow casting a sizeless built-in type to itself. if (DestType->isSizelessBuiltinType() && Self.Context.hasSameUnqualifiedType(DestType, SrcType)) { Kind = CK_NoOp; return; } // Allow bitcasting between compatible SVE vector types. if ((SrcType->isVectorType() || DestType->isVectorType()) && Self.isValidSveBitcast(SrcType, DestType)) { Kind = CK_BitCast; return; } if (!DestType->isScalarType() && !DestType->isVectorType() && !DestType->isMatrixType()) { const RecordType *DestRecordTy = DestType->getAs(); if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ // GCC struct/union extension: allow cast to self. Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) << DestType << SrcExpr.get()->getSourceRange(); Kind = CK_NoOp; return; } // GCC's cast to union extension. if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { RecordDecl *RD = DestRecordTy->getDecl(); if (CastExpr::getTargetFieldForToUnionCast(RD, SrcType)) { Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) << SrcExpr.get()->getSourceRange(); Kind = CK_ToUnion; return; } else { Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) << SrcType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } } // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type. if (Self.getLangOpts().OpenCL && DestType->isEventT()) { Expr::EvalResult Result; if (SrcExpr.get()->EvaluateAsInt(Result, Self.Context)) { llvm::APSInt CastInt = Result.Val.getInt(); if (0 == CastInt) { Kind = CK_ZeroToOCLOpaqueType; return; } Self.Diag(OpRange.getBegin(), diag::err_opencl_cast_non_zero_to_event_t) << CastInt.toString(10) << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } } // Reject any other conversions to non-scalar types. Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) << DestType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } // The type we're casting to is known to be a scalar, a vector, or a matrix. // Require the operand to be a scalar, a vector, or a matrix. if (!SrcType->isScalarType() && !SrcType->isVectorType() && !SrcType->isMatrixType()) { Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_typecheck_expect_scalar_operand) << SrcType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } if (DestType->isExtVectorType()) { SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind); return; } if (DestType->getAs() || SrcType->getAs()) { if (Self.CheckMatrixCast(OpRange, DestType, SrcType, Kind)) SrcExpr = ExprError(); return; } if (const VectorType *DestVecTy = DestType->getAs()) { if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && (SrcType->isIntegerType() || SrcType->isFloatingType())) { Kind = CK_VectorSplat; SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { SrcExpr = ExprError(); } return; } if (SrcType->isVectorType()) { if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) SrcExpr = ExprError(); return; } // The source and target types are both scalars, i.e. // - arithmetic types (fundamental, enum, and complex) // - all kinds of pointers // Note that member pointers were filtered out with C++, above. if (isa(SrcExpr.get())) { Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); SrcExpr = ExprError(); return; } // Can't cast to or from bfloat if (DestType->isBFloat16Type() && !SrcType->isBFloat16Type()) { Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_to_bfloat16) << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } if (SrcType->isBFloat16Type() && !DestType->isBFloat16Type()) { Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_from_bfloat16) << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } // If either type is a pointer, the other type has to be either an // integer or a pointer. if (!DestType->isArithmeticType()) { if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_pointer_from_non_pointer_int) << SrcType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } checkIntToPointerCast(/* CStyle */ true, OpRange, SrcExpr.get(), DestType, Self); } else if (!SrcType->isArithmeticType()) { if (!DestType->isIntegralType(Self.Context) && DestType->isArithmeticType()) { Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_cast_pointer_to_non_pointer_int) << DestType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } if ((Self.Context.getTypeSize(SrcType) > Self.Context.getTypeSize(DestType)) && !DestType->isBooleanType()) { // C 6.3.2.3p6: Any pointer type may be converted to an integer type. // Except as previously specified, the result is implementation-defined. // If the result cannot be represented in the integer type, the behavior // is undefined. The result need not be in the range of values of any // integer type. unsigned Diag; if (SrcType->isVoidPointerType()) Diag = DestType->isEnumeralType() ? diag::warn_void_pointer_to_enum_cast : diag::warn_void_pointer_to_int_cast; else if (DestType->isEnumeralType()) Diag = diag::warn_pointer_to_enum_cast; else Diag = diag::warn_pointer_to_int_cast; Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange; } } if (Self.getLangOpts().OpenCL && !Self.getOpenCLOptions().isAvailableOption( "cl_khr_fp16", Self.getLangOpts())) { if (DestType->isHalfType()) { Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_opencl_cast_to_half) << DestType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } } // ARC imposes extra restrictions on casts. if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) { checkObjCConversion(Sema::CCK_CStyleCast); if (SrcExpr.isInvalid()) return; const PointerType *CastPtr = DestType->getAs(); if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) { if (const PointerType *ExprPtr = SrcType->getAs()) { Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); if (CastPtr->getPointeeType()->isObjCLifetimeType() && ExprPtr->getPointeeType()->isObjCLifetimeType() && !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_typecheck_incompatible_ownership) << SrcType << DestType << Sema::AA_Casting << SrcExpr.get()->getSourceRange(); return; } } } else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_arc_convesion_of_weak_unavailable) << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); SrcExpr = ExprError(); return; } } if (!checkCastFunctionType(Self, SrcExpr, DestType)) Self.Diag(OpRange.getBegin(), diag::warn_cast_function_type) << SrcType << DestType << OpRange; DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); DiagnoseBadFunctionCast(Self, SrcExpr, DestType); Kind = Self.PrepareScalarCast(SrcExpr, DestType); if (SrcExpr.isInvalid()) return; if (Kind == CK_BitCast) checkCastAlign(); } void CastOperation::CheckBuiltinBitCast() { QualType SrcType = SrcExpr.get()->getType(); if (Self.RequireCompleteType(OpRange.getBegin(), DestType, diag::err_typecheck_cast_to_incomplete) || Self.RequireCompleteType(OpRange.getBegin(), SrcType, diag::err_incomplete_type)) { SrcExpr = ExprError(); return; } if (SrcExpr.get()->isRValue()) SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(), /*IsLValueReference=*/false); CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType); CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType); if (DestSize != SourceSize) { Self.Diag(OpRange.getBegin(), diag::err_bit_cast_type_size_mismatch) << (int)SourceSize.getQuantity() << (int)DestSize.getQuantity(); SrcExpr = ExprError(); return; } if (!DestType.isTriviallyCopyableType(Self.Context)) { Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable) << 1; SrcExpr = ExprError(); return; } if (!SrcType.isTriviallyCopyableType(Self.Context)) { Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable) << 0; SrcExpr = ExprError(); return; } Kind = CK_LValueToRValueBitCast; } /// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either /// const, volatile or both. static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, QualType DestType) { if (SrcExpr.isInvalid()) return; QualType SrcType = SrcExpr.get()->getType(); if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) || DestType->isLValueReferenceType())) return; QualType TheOffendingSrcType, TheOffendingDestType; Qualifiers CastAwayQualifiers; if (CastsAwayConstness(Self, SrcType, DestType, true, false, &TheOffendingSrcType, &TheOffendingDestType, &CastAwayQualifiers) != CastAwayConstnessKind::CACK_Similar) return; // FIXME: 'restrict' is not properly handled here. int qualifiers = -1; if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) { qualifiers = 0; } else if (CastAwayQualifiers.hasConst()) { qualifiers = 1; } else if (CastAwayQualifiers.hasVolatile()) { qualifiers = 2; } // This is a variant of int **x; const int **y = (const int **)x; if (qualifiers == -1) Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual2) << SrcType << DestType; else Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual) << TheOffendingSrcType << TheOffendingDestType << qualifiers; } ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, TypeSourceInfo *CastTypeInfo, SourceLocation RPLoc, Expr *CastExpr) { CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); Op.OpRange = SourceRange(LPLoc, CastExpr->getEndLoc()); if (getLangOpts().CPlusPlus) { Op.CheckCXXCStyleCast(/*FunctionalCast=*/ false, isa(CastExpr)); } else { Op.CheckCStyleCast(); } if (Op.SrcExpr.isInvalid()) return ExprError(); // -Wcast-qual DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType); return Op.complete(CStyleCastExpr::Create( Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(), &Op.BasePath, CurFPFeatureOverrides(), CastTypeInfo, LPLoc, RPLoc)); } ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, QualType Type, SourceLocation LPLoc, Expr *CastExpr, SourceLocation RPLoc) { assert(LPLoc.isValid() && "List-initialization shouldn't get here."); CastOperation Op(*this, Type, CastExpr); Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getEndLoc()); Op.CheckCXXCStyleCast(/*FunctionalCast=*/true, /*ListInit=*/false); if (Op.SrcExpr.isInvalid()) return ExprError(); auto *SubExpr = Op.SrcExpr.get(); if (auto *BindExpr = dyn_cast(SubExpr)) SubExpr = BindExpr->getSubExpr(); if (auto *ConstructExpr = dyn_cast(SubExpr)) ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc)); return Op.complete(CXXFunctionalCastExpr::Create( Context, Op.ResultType, Op.ValueKind, CastTypeInfo, Op.Kind, Op.SrcExpr.get(), &Op.BasePath, CurFPFeatureOverrides(), LPLoc, RPLoc)); }