diff options
Diffstat (limited to 'clang/lib/Sema/SemaCXXCast.cpp')
| -rw-r--r-- | clang/lib/Sema/SemaCXXCast.cpp | 1127 |
1 files changed, 620 insertions, 507 deletions
diff --git a/clang/lib/Sema/SemaCXXCast.cpp b/clang/lib/Sema/SemaCXXCast.cpp index daf6800ea0c..f83a9f291a6 100644 --- a/clang/lib/Sema/SemaCXXCast.cpp +++ b/clang/lib/Sema/SemaCXXCast.cpp @@ -19,11 +19,20 @@ #include <set> using namespace clang; -enum TryStaticCastResult { - TSC_NotApplicable, ///< The cast method is not applicable. - TSC_Success, ///< The cast method is appropriate and successful. - TSC_Failed ///< The cast method is appropriate, but failed. A - ///< diagnostic has been emitted. +enum TryCastResult { + TC_NotApplicable, ///< The cast method is not applicable. + TC_Success, ///< The cast method is appropriate and successful. + TC_Failed ///< The cast method is appropriate, but failed. A + ///< diagnostic has been emitted. +}; + +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) }; static void CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType, @@ -39,22 +48,51 @@ static void CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, const SourceRange &DestRange); static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType); -static TryStaticCastResult TryLValueToRValueCast( - Sema &Self, Expr *SrcExpr, QualType DestType, const SourceRange &OpRange); -static TryStaticCastResult TryStaticReferenceDowncast( - Sema &Self, Expr *SrcExpr, QualType DestType, const SourceRange &OpRange); -static TryStaticCastResult TryStaticPointerDowncast( - Sema &Self, QualType SrcType, QualType DestType, const SourceRange &OpRange); -static TryStaticCastResult TryStaticMemberPointerUpcast( - Sema &Self, QualType SrcType, QualType DestType, const SourceRange &OpRange); -static TryStaticCastResult TryStaticDowncast(Sema &Self, QualType SrcType, - QualType DestType, - const SourceRange &OpRange, - QualType OrigSrcType, - QualType OrigDestType); -static TryStaticCastResult TryStaticImplicitCast(Sema &Self, Expr *SrcExpr, - QualType DestType, - const SourceRange &OpRange); + +// 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, unsigned &msg); +static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg); +static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg); +static TryCastResult TryStaticDowncast(Sema &Self, QualType SrcType, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + QualType OrigSrcType, + QualType OrigDestType, unsigned &msg); +static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, + QualType DestType,bool CStyle, + const SourceRange &OpRange, + unsigned &msg); +static TryCastResult TryStaticImplicitCast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg); +static TryCastResult TryStaticCast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg); +static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, + bool CStyle, unsigned &msg); +static TryCastResult TryReinterpretCast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg); /// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's. Action::OwningExprResult @@ -104,336 +142,208 @@ Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, return ExprError(); } -/// 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 -CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType, - const SourceRange &OpRange, const SourceRange &DestRange) +/// CastsAwayConstness - Check if the pointer conversion from SrcType to +/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by +/// the cast checkers. Both arguments must denote pointer (possibly to member) +/// types. +bool +CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType) { - QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType(); - - DestType = Self.Context.getCanonicalType(DestType); - QualType SrcType = SrcExpr->getType(); - if (const LValueReferenceType *DestTypeTmp = - DestType->getAsLValueReferenceType()) { - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { - // Cannot cast non-lvalue to lvalue reference type. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) - << "const_cast" << OrigDestType << SrcExpr->getSourceRange(); - return; - } - - // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 - // [...] if a pointer to T1 can be [cast] to the type pointer to T2. - DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); - SrcType = Self.Context.getPointerType(SrcType); - } else { - // C++ 5.2.11p1: Otherwise, the result is an rvalue and the - // lvalue-to-rvalue, array-to-pointer, and function-to-pointer standard - // conversions are performed on the expression. - Self.DefaultFunctionArrayConversion(SrcExpr); - SrcType = SrcExpr->getType(); - } - - // 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. + // Casting away constness is defined in C++ 5.2.11p8 with reference to + // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since + // the rules are non-trivial. So first we construct Tcv *...cv* as described + // in C++ 5.2.11p8. + assert((SrcType->isPointerType() || SrcType->isMemberPointerType()) && + "Source type is not pointer or pointer to member."); + assert((DestType->isPointerType() || DestType->isMemberPointerType()) && + "Destination type is not pointer or pointer to member."); - if (!DestType->isPointerType() && !DestType->isMemberPointerType()) { - // 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 [...] - Self.Diag(OpRange.getBegin(), diag::err_bad_const_cast_dest) - << OrigDestType << DestRange; - return; - } - 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. - Self.Diag(OpRange.getBegin(), diag::err_bad_const_cast_dest) - << OrigDestType << DestRange; - return; - } - SrcType = Self.Context.getCanonicalType(SrcType); + QualType UnwrappedSrcType = SrcType, UnwrappedDestType = DestType; + llvm::SmallVector<unsigned, 8> cv1, cv2; - // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are - // completely equal. - // FIXME: const_cast should probably not be able to convert between pointers - // to different address spaces. - // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers - // in multi-level pointers may change, but the level count must be the same, - // as must be the final pointee type. - while (SrcType != DestType && - Self.UnwrapSimilarPointerTypes(SrcType, DestType)) { - SrcType = SrcType.getUnqualifiedType(); - DestType = DestType.getUnqualifiedType(); + // Find the qualifications. + while (Self.UnwrapSimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { + cv1.push_back(UnwrappedSrcType.getCVRQualifiers()); + cv2.push_back(UnwrappedDestType.getCVRQualifiers()); } + assert(cv1.size() > 0 && "Must have at least one pointer level."); - // Doug Gregor said to disallow this until users complain. -#if 0 - // If we end up with constant arrays of equal size, unwrap those too. A cast - // from const int [N] to int (&)[N] is invalid by my reading of the - // standard, but g++ accepts it even with -ansi -pedantic. - // No more than one level, though, so don't embed this in the unwrap loop - // above. - const ConstantArrayType *SrcTypeArr, *DestTypeArr; - if ((SrcTypeArr = Self.Context.getAsConstantArrayType(SrcType)) && - (DestTypeArr = Self.Context.getAsConstantArrayType(DestType))) + // Construct void pointers with those qualifiers (in reverse order of + // unwrapping, of course). + QualType SrcConstruct = Self.Context.VoidTy; + QualType DestConstruct = Self.Context.VoidTy; + for (llvm::SmallVector<unsigned, 8>::reverse_iterator i1 = cv1.rbegin(), + i2 = cv2.rbegin(); + i1 != cv1.rend(); ++i1, ++i2) { - if (SrcTypeArr->getSize() != DestTypeArr->getSize()) { - // Different array sizes. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "const_cast" << OrigDestType << OrigSrcType << OpRange; - return; - } - SrcType = SrcTypeArr->getElementType().getUnqualifiedType(); - DestType = DestTypeArr->getElementType().getUnqualifiedType(); + SrcConstruct = Self.Context.getPointerType( + SrcConstruct.getQualifiedType(*i1)); + DestConstruct = Self.Context.getPointerType( + DestConstruct.getQualifiedType(*i2)); } -#endif - // Since we're dealing in canonical types, the remainder must be the same. - if (SrcType != DestType) { - // Cast between unrelated types. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "const_cast" << OrigDestType << OrigSrcType << OpRange; - return; - } + // Test if they're compatible. + return SrcConstruct != DestConstruct && + !Self.IsQualificationConversion(SrcConstruct, DestConstruct); } -/// 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); +/// 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 -CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType, - const SourceRange &OpRange, const SourceRange &DestRange) +CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, + const SourceRange &OpRange, + const SourceRange &DestRange) { QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType(); - DestType = Self.Context.getCanonicalType(DestType); - QualType SrcType = SrcExpr->getType(); - if (const LValueReferenceType *DestTypeTmp = - DestType->getAsLValueReferenceType()) { - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { - // Cannot cast non-lvalue to reference type. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) - << "reinterpret_cast" << OrigDestType << SrcExpr->getSourceRange(); - return; - } - // 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. - // This code does this transformation for the checked types. - DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); - SrcType = Self.Context.getPointerType(SrcType); - } else if (const RValueReferenceType *DestTypeTmp = - DestType->getAsRValueReferenceType()) { - // Both the reference conversion and the rvalue rules apply. - Self.DefaultFunctionArrayConversion(SrcExpr); - SrcType = SrcExpr->getType(); + // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, + // or "pointer to cv void". - DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); - SrcType = Self.Context.getPointerType(SrcType); + QualType DestPointee; + const PointerType *DestPointer = DestType->getAsPointerType(); + const ReferenceType *DestReference = DestType->getAsReferenceType(); + if (DestPointer) { + DestPointee = DestPointer->getPointeeType(); + } else if (DestReference) { + DestPointee = DestReference->getPointeeType(); } else { - // C++ 5.2.10p1: [...] the lvalue-to-rvalue, array-to-pointer, and - // function-to-pointer standard conversions are performed on the - // expression v. - Self.DefaultFunctionArrayConversion(SrcExpr); - SrcType = SrcExpr->getType(); - } - - // Canonicalize source for comparison. - SrcType = Self.Context.getCanonicalType(SrcType); - - const MemberPointerType *DestMemPtr = DestType->getAsMemberPointerType(), - *SrcMemPtr = SrcType->getAsMemberPointerType(); - 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->getPointeeType()->isFunctionType() != - SrcMemPtr->getPointeeType()->isFunctionType()) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "reinterpret_cast" << OrigDestType << OrigSrcType << OpRange; - return; - } - - // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away - // constness. - if (CastsAwayConstness(Self, SrcType, DestType)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away) - << "reinterpret_cast" << OrigDestType << OrigSrcType << OpRange; - return; - } - - // A valid member pointer cast. - return; - } - - // See below for the enumeral issue. - if (SrcType->isNullPtrType() && DestType->isIntegralType() && - !DestType->isEnumeralType()) { - // 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)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_small_int) - << OrigDestType << DestRange; - } + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) + << OrigDestType << DestRange; return; } - bool destIsPtr = DestType->isPointerType(); - bool srcIsPtr = SrcType->isPointerType(); - 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. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "reinterpret_cast" << OrigDestType << OrigSrcType << OpRange; + const RecordType *DestRecord = DestPointee->getAsRecordType(); + 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)) + return; + } else { + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) + << DestPointee.getUnqualifiedType() << DestRange; return; } - 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. The intent is not - // entirely clear here, since all other paragraphs explicitly forbid casts - // to the same type. However, the behavior of compilers is pretty consistent - // on this point: allow same-type conversion if the involved types are - // pointers, disallow otherwise. - 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 effective class type, + // [...] - // Note: Clang treats enumeration types as integral types. If this is ever - // changed for C++, the additional check here will be redundant. - if (DestType->isIntegralType() && !DestType->isEnumeralType()) { - 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. - if (Self.Context.getTypeSize(SrcType) > - Self.Context.getTypeSize(DestType)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_small_int) - << OrigDestType << DestRange; + QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); + QualType SrcPointee; + if (DestPointer) { + if (const PointerType *SrcPointer = SrcType->getAsPointerType()) { + SrcPointee = SrcPointer->getPointeeType(); + } else { + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) + << OrigSrcType << SrcExpr->getSourceRange(); + return; } - return; + } else if (DestReference->isLValueReferenceType()) { + if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { + Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) + << CT_Dynamic << OrigSrcType << OrigDestType << OpRange; + } + SrcPointee = SrcType; + } else { + SrcPointee = SrcType; } - if (SrcType->isIntegralType() || SrcType->isEnumeralType()) { - assert(destIsPtr && "One type must be a pointer"); - // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly - // converted to a pointer. + const RecordType *SrcRecord = SrcPointee->getAsRecordType(); + if (SrcRecord) { + if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, + diag::err_bad_dynamic_cast_incomplete, + SrcExpr->getSourceRange())) + return; + } else { + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) + << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange(); return; } - if (!destIsPtr || !srcIsPtr) { - // With the valid non-pointer conversions out of the way, we can be even - // more stringent. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "reinterpret_cast" << OrigDestType << OrigSrcType << OpRange; - 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++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. - if (CastsAwayConstness(Self, SrcType, DestType)) { + // 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_const_away) - << "reinterpret_cast" << OrigDestType << OrigSrcType << OpRange; + << CT_Dynamic << OrigSrcType << OrigDestType << OpRange; return; } - // 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; - } - - // 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. - if (!Self.getLangOptions().CPlusPlus0x) { - Self.Diag(OpRange.getBegin(), diag::ext_reinterpret_cast_fn_obj) - << OpRange; - } + // C++ 5.2.7p3: If the type of v is the same as the required result type, + // [except for cv]. + if (DestRecord == SrcRecord) { return; } - if (DestType->isFunctionPointerType()) { - // See above. - if (!Self.getLangOptions().CPlusPlus0x) { - Self.Diag(OpRange.getBegin(), diag::ext_reinterpret_cast_fn_obj) - << OpRange; - } + // C++ 5.2.7p5 + // Upcasts are resolved statically. + if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { + Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, + OpRange.getBegin(), OpRange); + // Diagnostic already emitted on error. return; } - // 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. + // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. + const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(Self.Context); + assert(SrcDecl && "Definition missing"); + if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { + Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) + << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange(); + } + + // Done. Everything else is run-time checks. } -/// CastsAwayConstness - Check if the pointer conversion from SrcType to -/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by -/// the cast checkers. Both arguments must denote pointer (possibly to member) -/// types. -bool -CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType) +/// 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 +CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType, + const SourceRange &OpRange, const SourceRange &DestRange) { - // Casting away constness is defined in C++ 5.2.11p8 with reference to - // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since - // the rules are non-trivial. So first we construct Tcv *...cv* as described - // in C++ 5.2.11p8. - assert((SrcType->isPointerType() || SrcType->isMemberPointerType()) && - "Source type is not pointer or pointer to member."); - assert((DestType->isPointerType() || DestType->isMemberPointerType()) && - "Destination type is not pointer or pointer to member."); - - QualType UnwrappedSrcType = SrcType, UnwrappedDestType = DestType; - llvm::SmallVector<unsigned, 8> cv1, cv2; + if (!DestType->isLValueReferenceType()) + Self.DefaultFunctionArrayConversion(SrcExpr); - // Find the qualifications. - while (Self.UnwrapSimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { - cv1.push_back(UnwrappedSrcType.getCVRQualifiers()); - cv2.push_back(UnwrappedDestType.getCVRQualifiers()); - } - assert(cv1.size() > 0 && "Must have at least one pointer level."); + unsigned msg = diag::err_bad_cxx_cast_generic; + if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success + && msg != 0) + Self.Diag(OpRange.getBegin(), msg) << CT_Const + << SrcExpr->getType() << DestType << OpRange; +} - // Construct void pointers with those qualifiers (in reverse order of - // unwrapping, of course). - QualType SrcConstruct = Self.Context.VoidTy; - QualType DestConstruct = Self.Context.VoidTy; - for (llvm::SmallVector<unsigned, 8>::reverse_iterator i1 = cv1.rbegin(), - i2 = cv2.rbegin(); - i1 != cv1.rend(); ++i1, ++i2) - { - SrcConstruct = Self.Context.getPointerType( - SrcConstruct.getQualifiedType(*i1)); - DestConstruct = Self.Context.getPointerType( - DestConstruct.getQualifiedType(*i2)); - } +/// 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 +CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType, + const SourceRange &OpRange, const SourceRange &DestRange) +{ + if (!DestType->isLValueReferenceType()) + Self.DefaultFunctionArrayConversion(SrcExpr); - // Test if they're compatible. - return SrcConstruct != DestConstruct && - !Self.IsQualificationConversion(SrcConstruct, DestConstruct); + unsigned msg = diag::err_bad_cxx_cast_generic; + if (TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange, msg) + != TC_Success && msg != 0) + Self.Diag(OpRange.getBegin(), msg) << CT_Reinterpret + << SrcExpr->getType() << DestType << OpRange; } + /// 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. @@ -441,6 +351,31 @@ void CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType, const SourceRange &OpRange) { + // 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()) { + return; + } + + if (!DestType->isLValueReferenceType()) + Self.DefaultFunctionArrayConversion(SrcExpr); + + unsigned msg = diag::err_bad_cxx_cast_generic; + if (TryStaticCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange, msg) + != TC_Success && msg != 0) + Self.Diag(OpRange.getBegin(), msg) << CT_Static + << SrcExpr->getType() << DestType << OpRange; +} + +/// 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, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg) +{ // The order the tests is not entirely arbitrary. There is one conversion // that can be handled in two different ways. Given: // struct A {}; @@ -453,45 +388,39 @@ CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType, // conversion using B's conversion constructor. // DR 427 specifies that the downcast is to be applied here. - // FIXME: With N2812, casts to rvalue refs will change. - // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". - if (DestType->isVoidType()) { - return; - } + // 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. - if (TryStaticReferenceDowncast(Self, SrcExpr, DestType, OpRange) - > TSC_NotApplicable) { - return; - } + tcr = TryStaticReferenceDowncast(Self, SrcExpr, DestType, CStyle,OpRange,msg); + if (tcr != TC_NotApplicable) + return tcr; // N2844 5.2.9p3: An lvalue of type "cv1 T1" can be cast to type "rvalue // reference to cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". - if (TryLValueToRValueCast(Self, SrcExpr, DestType, OpRange) > - TSC_NotApplicable) { - return; - } + tcr = TryLValueToRValueCast(Self, SrcExpr, DestType, 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, [...]. - if (TryStaticImplicitCast(Self, SrcExpr, DestType, OpRange) > - TSC_NotApplicable) { - return; - } + tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CStyle, OpRange, msg); + 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. - // The lvalue-to-rvalue, array-to-pointer and function-to-pointer conversions - // are applied to the expression. QualType OrigSrcType = SrcExpr->getType(); - Self.DefaultFunctionArrayConversion(SrcExpr); QualType SrcType = Self.Context.getCanonicalType(SrcExpr->getType()); @@ -506,25 +435,23 @@ CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType, if (DestType->isEnumeralType()) { if (SrcType->isComplexType() || SrcType->isVectorType()) { // Fall through - these cannot be converted. - } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) { - return; - } + } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) + return TC_Success; } // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. - if (TryStaticPointerDowncast(Self, SrcType, DestType, OpRange) - > TSC_NotApplicable) { - return; - } + tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg); + 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. - if (TryStaticMemberPointerUpcast(Self, SrcType, DestType, OpRange) - > TSC_NotApplicable) { - return; - } + tcr = TryStaticMemberPointerUpcast(Self, SrcType, DestType, CStyle, + OpRange, msg); + 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 @@ -537,59 +464,55 @@ CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType, if (DestPointee->isIncompleteOrObjectType()) { // This is definitely the intended conversion, but it might fail due // to a const violation. - if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away) - << "static_cast" << DestType << OrigSrcType << OpRange; + if (!CStyle && !DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { + msg = diag::err_bad_cxx_cast_const_away; + return TC_Failed; } - return; + return TC_Success; } } } } // We tried everything. Everything! Nothing works! :-( - // FIXME: Error reporting could be a lot better. Should store the reason why - // every substep failed and, at the end, select the most specific and report - // that. - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_generic) - << "static_cast" << DestType << OrigSrcType - << OpRange; + return TC_NotApplicable; } /// Tests whether a conversion according to N2844 is valid. -TryStaticCastResult +TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) + unsigned &msg) { // N2844 5.2.9p3: An lvalue 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->getAsRValueReferenceType(); if (!R) - return TSC_NotApplicable; + return TC_NotApplicable; if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) - return TSC_NotApplicable; + 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; if (Self.CompareReferenceRelationship(SrcExpr->getType(), R->getPointeeType(), DerivedToBase) < Sema::Ref_Compatible_With_Added_Qualification) { - Self.Diag(OpRange.getBegin(), diag::err_bad_lvalue_to_rvalue_cast) - << SrcExpr->getType() << R->getPointeeType() << OpRange; - return TSC_Failed; + msg = diag::err_bad_lvalue_to_rvalue_cast; + return TC_Failed; } // FIXME: Similar to CheckReferenceInit, we actually need more AST annotation // than nothing. - return TSC_Success; + return TC_Success; } /// Tests whether a conversion according to C++ 5.2.9p5 is valid. -TryStaticCastResult +TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) + bool CStyle, const SourceRange &OpRange, + unsigned &msg) { // 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, @@ -600,24 +523,27 @@ TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, // variant of this rule, the intent is clearly for it to apply to the this // conversion as well. - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { - return TSC_NotApplicable; - } - const ReferenceType *DestReference = DestType->getAsReferenceType(); if (!DestReference) { - return TSC_NotApplicable; + return TC_NotApplicable; + } + bool RValueRef = DestReference->isRValueReferenceType(); + if (!RValueRef && SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { + // 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(); - return TryStaticDowncast(Self, SrcExpr->getType(), DestPointee, OpRange, - SrcExpr->getType(), DestType); + return TryStaticDowncast(Self, SrcExpr->getType(), DestPointee, CStyle, + OpRange, SrcExpr->getType(), DestType, msg); } /// Tests whether a conversion according to C++ 5.2.9p8 is valid. -TryStaticCastResult +TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange) + bool CStyle, const SourceRange &OpRange, unsigned &msg) { // 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 @@ -627,38 +553,39 @@ TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, // In addition, DR54 clarifies that the base must be accessible in the // current context. - const PointerType *SrcPointer = SrcType->getAsPointerType(); - if (!SrcPointer) { - return TSC_NotApplicable; - } - const PointerType *DestPointer = DestType->getAsPointerType(); if (!DestPointer) { - return TSC_NotApplicable; + return TC_NotApplicable; + } + + const PointerType *SrcPointer = SrcType->getAsPointerType(); + if (!SrcPointer) { + msg = diag::err_bad_static_cast_pointer_nonpointer; + return TC_NotApplicable; } return TryStaticDowncast(Self, SrcPointer->getPointeeType(), - DestPointer->getPointeeType(), - OpRange, SrcType, DestType); + DestPointer->getPointeeType(), CStyle, + OpRange, SrcType, DestType, msg); } /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to /// DestType, both of which must be canonical, is possible and allowed. -TryStaticCastResult +TryCastResult TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange, QualType OrigSrcType, - QualType OrigDestType) + bool CStyle, const SourceRange &OpRange, QualType OrigSrcType, + QualType OrigDestType, unsigned &msg) { // Downcast can only happen in class hierarchies, so we need classes. if (!DestType->isRecordType() || !SrcType->isRecordType()) { - return TSC_NotApplicable; + return TC_NotApplicable; } - BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false, + BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle, /*DetectVirtual=*/true); if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { - return TSC_NotApplicable; + return TC_NotApplicable; } // Target type does derive from source type. Now we're serious. If an error @@ -679,11 +606,10 @@ TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, // 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. - if (!DestType.isAtLeastAsQualifiedAs(SrcType)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away) - << "static_cast" << OrigDestType << OrigSrcType << OpRange; - return TSC_Failed; + // Must preserve cv, as always, unless we're in C-style mode. + if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { + msg = diag::err_bad_cxx_cast_const_away; + return TC_Failed; } if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { @@ -691,20 +617,22 @@ TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, // 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. - Paths.clear(); - Paths.setRecordingPaths(true); - Self.IsDerivedFrom(DestType, SrcType, Paths); + if (!Paths.isRecordingPaths()) { + Paths.clear(); + Paths.setRecordingPaths(true); + Self.IsDerivedFrom(DestType, SrcType, Paths); + } std::string PathDisplayStr; std::set<unsigned> DisplayedPaths; - for (BasePaths::paths_iterator Path = Paths.begin(); - Path != Paths.end(); ++Path) { - if (DisplayedPaths.insert(Path->back().SubobjectNumber).second) { + for (BasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end(); + PI != PE; ++PI) { + if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) { // We haven't displayed a path to this particular base // class subobject yet. PathDisplayStr += "\n "; - for (BasePath::const_reverse_iterator Element = Path->rbegin(); - Element != Path->rend(); ++Element) - PathDisplayStr += Element->Base->getType().getAsString() + " -> "; + for (BasePath::const_reverse_iterator EI = PI->rbegin(),EE = PI->rend(); + EI != EE; ++EI) + PathDisplayStr += EI->Base->getType().getAsString() + " -> "; PathDisplayStr += DestType.getAsString(); } } @@ -712,19 +640,26 @@ TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) << SrcType.getUnqualifiedType() << DestType.getUnqualifiedType() << PathDisplayStr << OpRange; - return TSC_Failed; + msg = 0; + return TC_Failed; } if (Paths.getDetectedVirtual() != 0) { QualType VirtualBase(Paths.getDetectedVirtual(), 0); Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) << OrigSrcType << OrigDestType << VirtualBase << OpRange; - return TSC_Failed; + msg = 0; + return TC_Failed; } - // FIXME: Test accessibility. + if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType, + diag::err_downcast_from_inaccessible_base, Paths, + OpRange.getBegin(), DeclarationName())) { + msg = 0; + return TC_Failed; + } - return TSC_Success; + return TC_Success; } /// TryStaticMemberPointerUpcast - Tests whether a conversion according to @@ -734,31 +669,34 @@ TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, /// converted to an rvalue of type "pointer to member of B of type cv2 T", /// where B is a base class of D [...]. /// -TryStaticCastResult +TryCastResult TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange) + bool CStyle, const SourceRange &OpRange, + unsigned &msg) { - const MemberPointerType *SrcMemPtr = SrcType->getAsMemberPointerType(); - if (!SrcMemPtr) - return TSC_NotApplicable; const MemberPointerType *DestMemPtr = DestType->getAsMemberPointerType(); if (!DestMemPtr) - return TSC_NotApplicable; + return TC_NotApplicable; + const MemberPointerType *SrcMemPtr = SrcType->getAsMemberPointerType(); + if (!SrcMemPtr) { + msg = diag::err_bad_static_cast_member_pointer_nonmp; + return TC_NotApplicable; + } // T == T, modulo cv if (Self.Context.getCanonicalType( SrcMemPtr->getPointeeType().getUnqualifiedType()) != Self.Context.getCanonicalType(DestMemPtr->getPointeeType(). getUnqualifiedType())) - return TSC_NotApplicable; + return TC_NotApplicable; // B base of D QualType SrcClass(SrcMemPtr->getClass(), 0); QualType DestClass(DestMemPtr->getClass(), 0); - BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false, + BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle, /*DetectVirtual=*/true); if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { - return TSC_NotApplicable; + return TC_NotApplicable; } // B is a base of D. But is it an allowed base? If not, it's a hard error. @@ -771,18 +709,25 @@ TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType, std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; - return TSC_Failed; + 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; - return TSC_Failed; + msg = 0; + return TC_Failed; } - // FIXME: Test accessibility. + if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType, + diag::err_downcast_from_inaccessible_base, Paths, + OpRange.getBegin(), DeclarationName())) { + msg = 0; + return TC_Failed; + } - return TSC_Success; + return TC_Success; } /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 @@ -790,143 +735,311 @@ TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType, /// /// 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 [...]. -TryStaticCastResult +TryCastResult TryStaticImplicitCast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) + bool CStyle, const SourceRange &OpRange, unsigned &msg) { if (DestType->isReferenceType()) { // At this point of CheckStaticCast, if the destination is a reference, // this has to work. There is no other way that works. - return Self.CheckReferenceInit(SrcExpr, DestType) ? - TSC_Failed : TSC_Success; + // On the other hand, if we're checking a C-style cast, we've still got + // the reinterpret_cast way. In that case, we pass an ICS so we don't + // get error messages. + ImplicitConversionSequence ICS; + bool failed = Self.CheckReferenceInit(SrcExpr, DestType, CStyle ? &ICS : 0); + if (!failed) + return TC_Success; + if (CStyle) + return TC_NotApplicable; + // If we didn't pass the ICS, we already got an error message. + msg = 0; + return TC_Failed; } if (DestType->isRecordType()) { - // FIXME: Use an implementation of C++ [over.match.ctor] for this. - return TSC_NotApplicable; + // There are no further possibilities for the target type being a class, + // neither in static_cast nor in a C-style cast. So we can fail here. + // FIXME: We need to store this constructor in the AST. + if (Self.PerformInitializationByConstructor(DestType, &SrcExpr, 1, + OpRange.getBegin(), OpRange, DeclarationName(), Sema::IK_Direct)) + return TC_Success; + // The function already emitted an error. + msg = 0; + return TC_Failed; } // FIXME: To get a proper error from invalid conversions here, we need to // reimplement more of this. + // FIXME: This does not actually perform the conversion, and thus does not + // check for ambiguity or access. ImplicitConversionSequence ICS = Self.TryImplicitConversion( SrcExpr, DestType); return ICS.ConversionKind == ImplicitConversionSequence::BadConversion ? - TSC_NotApplicable : TSC_Success; + TC_NotApplicable : TC_Success; } -/// 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 -CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, - const SourceRange &OpRange, - const SourceRange &DestRange) -{ - QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType(); +/// TryConstCast - See if a const_cast from source to destination is allowed, +/// and perform it if it is. +static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, + bool CStyle, unsigned &msg) { DestType = Self.Context.getCanonicalType(DestType); + QualType SrcType = SrcExpr->getType(); + if (const LValueReferenceType *DestTypeTmp = + DestType->getAsLValueReferenceType()) { + if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { + // 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; + } - // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, - // or "pointer to cv void". + // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 + // [...] if a pointer to T1 can be [cast] to the type pointer to T2. + DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); + SrcType = Self.Context.getPointerType(SrcType); + } - QualType DestPointee; - const PointerType *DestPointer = DestType->getAsPointerType(); - const ReferenceType *DestReference = DestType->getAsReferenceType(); - if (DestPointer) { - DestPointee = DestPointer->getPointeeType(); - } else if (DestReference) { - DestPointee = DestReference->getPointeeType(); - } else { - Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) - << OrigDestType << DestRange; - return; + // 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()) { + // 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; } + SrcType = Self.Context.getCanonicalType(SrcType); - const RecordType *DestRecord = DestPointee->getAsRecordType(); - 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)) - return; - } else { - Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) - << DestPointee.getUnqualifiedType() << DestRange; - return; + // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are + // completely equal. + // FIXME: const_cast should probably not be able to convert between pointers + // to different address spaces. + // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers + // in multi-level pointers may change, but the level count must be the same, + // as must be the final pointee type. + while (SrcType != DestType && + Self.UnwrapSimilarPointerTypes(SrcType, DestType)) { + SrcType = SrcType.getUnqualifiedType(); + DestType = DestType.getUnqualifiedType(); } - // 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 effective class type, - // [...] + // Since we're dealing in canonical types, the remainder must be the same. + if (SrcType != DestType) + return TC_NotApplicable; - QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); - QualType SrcPointee; - if (DestPointer) { - if (const PointerType *SrcPointer = SrcType->getAsPointerType()) { - SrcPointee = SrcPointer->getPointeeType(); - } else { - Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) - << OrigSrcType << SrcExpr->getSourceRange(); - return; + return TC_Success; +} + +static TryCastResult TryReinterpretCast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + const SourceRange &OpRange, + unsigned &msg) { + QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType(); + + DestType = Self.Context.getCanonicalType(DestType); + QualType SrcType = SrcExpr->getType(); + if (const ReferenceType *DestTypeTmp = DestType->getAsReferenceType()) { + bool LValue = DestTypeTmp->isLValueReferenceType(); + if (LValue && SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { + // Cannot cast non-lvalue to reference type. See the similar comment in + // const_cast. + msg = diag::err_bad_cxx_cast_rvalue; + return TC_NotApplicable; } - } else if (DestReference->isLValueReferenceType()) { - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) - << "dynamic_cast" << OrigDestType << 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. + // This code does this transformation for the checked types. + DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); + SrcType = Self.Context.getPointerType(SrcType); + } + + // Canonicalize source for comparison. + SrcType = Self.Context.getCanonicalType(SrcType); + + const MemberPointerType *DestMemPtr = DestType->getAsMemberPointerType(), + *SrcMemPtr = SrcType->getAsMemberPointerType(); + 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->getPointeeType()->isFunctionType() != + SrcMemPtr->getPointeeType()->isFunctionType()) + return TC_NotApplicable; + + // 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 (!CStyle && CastsAwayConstness(Self, SrcType, DestType)) { + msg = diag::err_bad_cxx_cast_const_away; + return TC_Failed; } - SrcPointee = SrcType; - } else { - SrcPointee = SrcType; + + // A valid member pointer cast. + return TC_Success; } - const RecordType *SrcRecord = SrcPointee->getAsRecordType(); - if (SrcRecord) { - if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, - diag::err_bad_dynamic_cast_incomplete, - SrcExpr->getSourceRange())) - return; - } else { - Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) - << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange(); - return; + // See below for the enumeral issue. + if (SrcType->isNullPtrType() && DestType->isIntegralType() && + !DestType->isEnumeralType()) { + // 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; + } + return TC_Success; } - 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."); + bool destIsPtr = DestType->isPointerType(); + bool srcIsPtr = SrcType->isPointerType(); + 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; + } - // 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_const_away) - << "dynamic_cast" << OrigDestType << OrigSrcType << OpRange; - return; + 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. The intent is not + // entirely clear here, since all other paragraphs explicitly forbid casts + // to the same type. However, the behavior of compilers is pretty consistent + // on this point: allow same-type conversion if the involved types are + // pointers, disallow otherwise. + return TC_Success; } - // C++ 5.2.7p3: If the type of v is the same as the required result type, - // [except for cv]. - if (DestRecord == SrcRecord) { - return; + // Note: Clang treats enumeration types as integral types. If this is ever + // changed for C++, the additional check here will be redundant. + if (DestType->isIntegralType() && !DestType->isEnumeralType()) { + 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. + if (Self.Context.getTypeSize(SrcType) > + Self.Context.getTypeSize(DestType)) { + msg = diag::err_bad_reinterpret_cast_small_int; + return TC_Failed; + } + return TC_Success; } - // C++ 5.2.7p5 - // Upcasts are resolved statically. - if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { - Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, - OpRange.getBegin(), OpRange); - // Diagnostic already emitted on error. - return; + if (SrcType->isIntegralType() || SrcType->isEnumeralType()) { + assert(destIsPtr && "One type must be a pointer"); + // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly + // converted to a pointer. + return TC_Success; } - // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. - const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(Self.Context); - assert(SrcDecl && "Definition missing"); - if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { - Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) - << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange(); + if (!destIsPtr || !srcIsPtr) { + // With the valid non-pointer conversions out of the way, we can be even + // more stringent. + return TC_NotApplicable; } - // Done. Everything else is run-time checks. + // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. + // The C-style cast operator can. + if (!CStyle && CastsAwayConstness(Self, SrcType, DestType)) { + msg = diag::err_bad_cxx_cast_const_away; + return TC_Failed; + } + + // 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 TC_Success; + } + + // 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. + if (!Self.getLangOptions().CPlusPlus0x) + Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange; + return TC_Success; + } + + if (DestType->isFunctionPointerType()) { + // See above. + if (!Self.getLangOptions().CPlusPlus0x) + Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange; + return TC_Success; + } + + // 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 TC_Success; +} + + +bool Sema::CXXCheckCStyleCast(SourceRange R, QualType CastTy, Expr *&CastExpr) +{ + // 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 (CastTy->isVoidType()) + return false; + + // If the type is dependent, we won't do any other semantic analysis now. + if (CastTy->isDependentType() || CastExpr->isTypeDependent()) + return false; + + if (!CastTy->isLValueReferenceType()) + DefaultFunctionArrayConversion(CastExpr); + + // 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 ... + unsigned msg = diag::err_bad_cxx_cast_generic; + TryCastResult tcr = TryConstCast(*this, CastExpr, CastTy, /*CStyle*/true,msg); + if (tcr == TC_NotApplicable) { + // ... or if that is not possible, a static_cast, ignoring const, ... + tcr = TryStaticCast(*this, CastExpr, CastTy, /*CStyle*/true, R, msg); + if (tcr == TC_NotApplicable) { + // ... and finally a reinterpret_cast, ignoring const. + tcr = TryReinterpretCast(*this, CastExpr, CastTy, /*CStyle*/true, R, msg); + } + } + + // FIXME: Differentiate functional-style and C-style cast. + if (tcr != TC_Success && msg != 0) + Diag(R.getBegin(), msg) << CT_CStyle + << CastExpr->getType() << CastTy << R; + + return tcr != TC_Success; } |
