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Diffstat (limited to 'clang/lib/Sema/SemaCast.cpp')
| -rw-r--r-- | clang/lib/Sema/SemaCast.cpp | 2929 |
1 files changed, 2929 insertions, 0 deletions
diff --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp new file mode 100644 index 000000000000..0ebb5c68f7c2 --- /dev/null +++ b/clang/lib/Sema/SemaCast.cpp @@ -0,0 +1,2929 @@ +//===--- 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<int>(x)' +// +//===----------------------------------------------------------------------===// + +#include "clang/Sema/SemaInternal.h" +#include "clang/AST/ASTContext.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 "llvm/ADT/SmallVector.h" +#include <set> +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) +}; + +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 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<ImplicitCastExpr>(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()); + } + 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; + } + }; +} + +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); + + +/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_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_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, + 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: + 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_ViableCandidates; + 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<PointerType>()) { + From = Ptr->getPointeeType(); + DifferentPtrness++; + } + QualType To = src->getType(); + if (auto Ptr = To->getAs<PointerType>()) { + To = Ptr->getPointeeType(); + DifferentPtrness--; + } + if (!DifferentPtrness) { + auto RecFrom = From->getAs<RecordType>(); + auto RecTo = To->getAs<RecordType>(); + if (RecFrom && RecTo) { + auto DeclFrom = RecFrom->getAsCXXRecordDecl(); + if (!DeclFrom->isCompleteDefinition()) + S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) + << DeclFrom->getDeclName(); + auto DeclTo = RecTo->getAsCXXRecordDecl(); + if (!DeclTo->isCompleteDefinition()) + S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) + << DeclTo->getDeclName(); + } + } +} + +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\<DestType\>(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() { + 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<PointerType>(); + const ReferenceType *DestReference = nullptr; + if (DestPointer) { + DestPointee = DestPointer->getPointeeType(); + } else if ((DestReference = DestType->getAs<ReferenceType>())) { + 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<RecordType>(); + if (DestPointee->isVoidType()) { + assert(DestPointer && "Reference to void is not possible"); + } else if (DestRecord) { + if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, + diag::err_bad_dynamic_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<PointerType>()) { + SrcPointee = SrcPointer->getPointeeType(); + } else { + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) + << OrigSrcType << 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<RecordType>(); + if (SrcRecord) { + if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, + diag::err_bad_dynamic_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<CXXRecordDecl>(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; + } + + // Done. Everything else is run-time checks. + Kind = CK_Dynamic; +} + +/// CheckConstCast - Check that a const_cast\<DestType\>(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\<char*\>(str)); +void CastOperation::CheckConstCast() { + 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(); +} + +/// Check that a reinterpret_cast\<DestType\>(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"); +} + +/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is +/// valid. +/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code +/// like this: +/// char *bytes = reinterpret_cast\<char*\>(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<int>; 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); + } else { + SrcExpr = ExprError(); + } +} + + +/// CheckStaticCast - Check that a static_cast\<DestType\>(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() { + if (isPlaceholder()) { + checkNonOverloadPlaceholders(); + if (SrcExpr.isInvalid()) + 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<PointerType>(); + if (!SrcPtrType) + return false; + auto *DestPtrType = DestType->getAs<PointerType>(); + 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<const B&>(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<EnumType>()) { + 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 (SrcType->isIntegralOrEnumerationType()) { + Kind = 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<PointerType>()) { + QualType SrcPointee = SrcPointer->getPointeeType(); + if (SrcPointee->isVoidType()) { + if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { + 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<PointerType>()) + if (auto DestPointer = DestType->getAs<PointerType>()) + if (SrcPointer->getPointeeType()->getAs<RecordType>() && + DestPointer->getPointeeType()->getAs<RecordType>()) + 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<RValueReferenceType>(); + 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. + bool DerivedToBase; + bool ObjCConversion; + bool ObjCLifetimeConversion; + bool FunctionConversion; + QualType FromType = SrcExpr->getType(); + QualType ToType = R->getPointeeType(); + if (CStyle) { + FromType = FromType.getUnqualifiedType(); + ToType = ToType.getUnqualifiedType(); + } + + Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( + SrcExpr->getBeginLoc(), ToType, FromType, DerivedToBase, ObjCConversion, + ObjCLifetimeConversion, FunctionConversion); + 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 (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<ReferenceType>(); + 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<PointerType>(); + if (!DestPointer) { + return TC_NotApplicable; + } + + const PointerType *SrcPointer = SrcType->getAs<PointerType>(); + 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<RecordType>() || !SrcType->getAs<RecordType>()) { + 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<const B&>(*((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<unsigned> 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<MemberPointerType>(); + 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<CXXMethodDecl>(Fn); + SrcType = Self.Context.getMemberPointerType(Fn->getType(), + Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); + WasOverloadedFunction = true; + } + } + + const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); + 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_dynamic_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<ReferenceType>()) { + // 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<T2&>; + // -- a glvalue of type T1 can be explicitly converted to an xvalue of + // type T2 using the cast const_cast<T2&&>; 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<T2&&>. + + if (isa<LValueReferenceType>(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<RValueReferenceType>(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<T*>(&a) +// reinterpret_cast<T&>(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<PointerType>() || !DestType->getAs<PointerType>()) { + return; + } + SrcTy = SrcType->getPointeeType(); + DestTy = DestType->getPointeeType(); + } else { + if (!DestType->getAs<ReferenceType>()) { + 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<TagType>() || DestTy->getAs<TagType>()) { + 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<PointerType>()) + if (SrcPtrTy->isObjCSelType()) { + QualType DT = DestType; + if (isa<PointerType>(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<PointerType>()->getPointeeType()->castAs<FunctionType>(); + const auto *DstFTy = + DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); + 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<UnaryOperator>(Src)) + if (UO->getOpcode() == UO_AddrOf) + Src = UO->getSubExpr()->IgnoreParenImpCasts(); + auto *DRE = dyn_cast<DeclRefExpr>(Src); + if (!DRE) + return; + auto *FD = dyn_cast<FunctionDecl>(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<TokenValue, 6> 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, SourceLocation Loc, + 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(Loc, Diag) << SrcType << DestType; + } +} + +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.resolveAndFixAddressOfOnlyViableOverloadCandidate( + 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<ReferenceType>()) { + 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<T&>(x) has the + // same effect as the conversion *reinterpret_cast<T*>(&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_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<MemberPointerType>(), + *SrcMemPtr = SrcType->getAs<MemberPointerType>(); + 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) { + // 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; + } + + // 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). + bool MicrosoftException = Self.getLangOpts().MicrosoftExt && + !DestType->isBooleanType(); + if ((Self.Context.getTypeSize(SrcType) > + Self.Context.getTypeSize(DestType)) && + !MicrosoftException) { + 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.getBegin(), 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; + } + + // 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) { + 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(); + auto SrcPtrType = SrcType->getAs<PointerType>(); + if (!SrcPtrType) + return TC_NotApplicable; + auto DestPtrType = DestType->getAs<PointerType>(); + if (!DestPtrType) + return TC_NotApplicable; + auto SrcPointeeType = SrcPtrType->getPointeeType(); + auto DestPointeeType = DestPtrType->getPointeeType(); + if (SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace()) + return TC_NotApplicable; + if (!DestPtrType->isAddressSpaceOverlapping(*SrcPtrType)) { + 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()); + return Self.Context.hasSameType(SrcPointeeTypeWithoutAS, + DestPointeeTypeWithoutAS) + ? TC_Success + : 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<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) { + const PointerType *DestPPtr = cast<PointerType>(DestPtr); + const PointerType *SrcPPtr = cast<PointerType>(SrcPtr); + QualType DestPPointee = DestPPtr->getPointeeType(); + QualType SrcPPointee = SrcPPtr->getPointeeType(); + if (Nested ? DestPPointee.getAddressSpace() != + SrcPPointee.getAddressSpace() + : !DestPPtr->isAddressSpaceOverlapping(*SrcPPtr)) { + 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; + } + + // AltiVec vector initialization with a single literal. + if (const VectorType *vecTy = DestType->getAs<VectorType>()) + 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); + if (SrcExpr.isInvalid()) + return; + + if (isValidCast(tcr)) + Kind = CK_AddressSpaceConversion; + + if (tcr == TC_NotApplicable) { + // ... or if that is not possible, a static_cast, ignoring const, ... + 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. + 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(); + } 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<CallExpr>(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; + + 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; + } + + // 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; + } + + if (!DestType->isScalarType() && !DestType->isVectorType()) { + const RecordType *DestRecordTy = DestType->getAs<RecordType>(); + + 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 or vector. + + // Require the operand to be a scalar or vector. + if (!SrcType->isScalarType() && !SrcType->isVectorType()) { + 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 (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { + 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<ObjCSelectorExpr>(SrcExpr.get())) { + Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); + 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.getBegin(), 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.getLangOpts().OpenCL && + !Self.getOpenCLOptions().isEnabled("cl_khr_fp16")) { + 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<PointerType>(); + if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) { + if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { + 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; + } + } + + 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<InitListExpr>(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, 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<CXXBindTemporaryExpr>(SubExpr)) + SubExpr = BindExpr->getSubExpr(); + if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr)) + ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc)); + + return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, + Op.ValueKind, CastTypeInfo, Op.Kind, + Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc)); +} |