From 9cc11e70031365972424b43f439021d88096b146 Mon Sep 17 00:00:00 2001 From: Sebastian Redl Date: Sat, 25 Jul 2009 15:41:38 +0000 Subject: [PATCH] Implement C++ semantics for C-style and functional-style casts. This regresses Clang extension conversions, like vectors, but allows conversions via constructors and conversion operators. Add custom conversions to static_cast. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77076 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/clang/Basic/DiagnosticSemaKinds.td | 52 +- lib/Sema/Sema.h | 13 +- lib/Sema/SemaCXXCast.cpp | 1489 +++++++++++--------- lib/Sema/SemaExpr.cpp | 8 +- lib/Sema/SemaOverload.cpp | 2 +- test/Parser/cxx-ambig-paren-expr.cpp | 6 +- test/SemaCXX/cstyle-cast.cpp | 231 +++ test/SemaCXX/dcl_ambig_res.cpp | 2 +- test/SemaCXX/decl-expr-ambiguity.cpp | 2 +- test/SemaCXX/static-cast.cpp | 22 +- test/SemaTemplate/instantiate-cast.cpp | 8 +- www/cxx_status.html | 16 +- 12 files changed, 1109 insertions(+), 742 deletions(-) create mode 100644 test/SemaCXX/cstyle-cast.cpp diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td index 9d2b2a9adf..d9e6af455f 100644 --- a/include/clang/Basic/DiagnosticSemaKinds.td +++ b/include/clang/Basic/DiagnosticSemaKinds.td @@ -1395,36 +1395,46 @@ def note_property_impl_required : Note< // C++ casts -def err_bad_cxx_cast_generic : Error<"%0 from %2 to %1 is not allowed">; -def err_bad_cxx_cast_rvalue : Error<"%0 from rvalue to reference type %1">; +// These messages adhere to the TryCast pattern: %0 is an int specifying the +// cast type, %1 is the source type, %2 is the destination type. +def err_bad_cxx_cast_generic : Error< + "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|" + "functional-style cast}0 from %1 to %2 is not allowed">; +def err_bad_cxx_cast_rvalue : Error< + "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|" + "functional-style cast}0 from rvalue to reference type %2">; def err_bad_cxx_cast_const_away : Error< - "%0 from %2 to %1 casts away constness">; + "%select{const_cast|static_cast|reinterpret_cast|dynamic_cast|C-style cast|" + "functional-style cast}0 from %1 to %2 casts away constness">; def err_bad_const_cast_dest : Error< - "const_cast to %0, which is not a reference, pointer-to-object, " - "or pointer-to-data-member">; - -def err_bad_reinterpret_cast_same_type : Error< - "source and destination type of reinterpret_cast are not distinct">; -def ext_reinterpret_cast_fn_obj : Extension< - "reinterpret_cast between pointer-to-function and pointer-to-object is " - "an extension">; - + "%select{const_cast||||C-style cast|functional-style cast}0 to %2, " + "which is not a reference, pointer-to-object, or pointer-to-data-member">; +def ext_cast_fn_obj : Extension< + "cast between pointer-to-function and pointer-to-object is an extension">; def err_bad_reinterpret_cast_small_int : Error< - "cast from pointer to smaller type %0 loses information">; + "cast from pointer to smaller type %2 loses information">; +def err_bad_lvalue_to_rvalue_cast : Error< + "cannot cast from lvalue of type %1 to rvalue reference type %2; types are " + "not compatible">; +def err_bad_static_cast_pointer_nonpointer : Error< + "cannot cast from type %1 to pointer type %2">; +def err_bad_static_cast_member_pointer_nonmp : Error< + "cannot cast from type %1 to member pointer type %2">; + +// These messages don't adhere to the pattern. +// FIXME: Display the path somehow better. +def err_ambiguous_base_to_derived_cast : Error< + "ambiguous cast from base %0 to derived %1:%2">; +def err_static_downcast_via_virtual : Error< + "cannot cast %0 to %1 via virtual base %2">; +def err_downcast_from_inaccessible_base : Error< + "cannot cast %1 to %0 due to inaccessible conversion path">; def err_bad_dynamic_cast_not_ref_or_ptr : Error< "%0 is not a reference or pointer">; def err_bad_dynamic_cast_not_class : Error<"%0 is not a class">; def err_bad_dynamic_cast_incomplete : Error<"%0 is an incomplete type">; def err_bad_dynamic_cast_not_ptr : Error<"%0 is not a pointer">; def err_bad_dynamic_cast_not_polymorphic : Error<"%0 is not polymorphic">; -// FIXME: Display the path somehow better. -def err_ambiguous_base_to_derived_cast : Error< - "ambiguous static_cast from base %0 to derived %1:%2">; -def err_static_downcast_via_virtual : Error< - "cannot cast %0 to %1 via virtual base %2">; -def err_bad_lvalue_to_rvalue_cast : Error< - "cannot cast from lvalue of type %0 to rvalue reference to %1; types are " - "not compatible">; // Other C++ expressions def err_need_header_before_typeid : Error< diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h index 164c65f02c..c23002f9a0 100644 --- a/lib/Sema/Sema.h +++ b/lib/Sema/Sema.h @@ -3169,9 +3169,10 @@ public: bool AllowExplicit = false, bool ForceRValue = false); - /// CheckCastTypes - Check type constraints for casting between types. + /// CheckCastTypes - Check type constraints for casting between types under + /// C semantics. bool CheckCastTypes(SourceRange TyRange, QualType CastTy, Expr *&CastExpr); - + // CheckVectorCast - check type constraints for vectors. // Since vectors are an extension, there are no C standard reference for this. // We allow casting between vectors and integer datatypes of the same size. @@ -3184,7 +3185,11 @@ public: // or vectors and the element type of that vector. // returns true if the cast is invalid bool CheckExtVectorCast(SourceRange R, QualType VectorTy, QualType Ty); - + + /// CXXCheckCStyleCast - Check constraints of a C-style or function-style + /// cast under C++ semantics. + bool CXXCheckCStyleCast(SourceRange R, QualType CastTy, Expr *&CastExpr); + /// CheckMessageArgumentTypes - Check types in an Obj-C message send. /// \param Method - May be null. /// \param [out] ReturnType - The return type of the send. @@ -3196,7 +3201,7 @@ public: /// CheckCXXBooleanCondition - Returns true if conversion to bool is invalid. bool CheckCXXBooleanCondition(Expr *&CondExpr); - + /// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have /// the specified width and sign. If an overflow occurs, detect it and emit /// the specified diagnostic. diff --git a/lib/Sema/SemaCXXCast.cpp b/lib/Sema/SemaCXXCast.cpp index daf6800ea0..f83a9f291a 100644 --- a/lib/Sema/SemaCXXCast.cpp +++ b/lib/Sema/SemaCXXCast.cpp @@ -19,11 +19,20 @@ #include 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 @@ -104,291 +142,6 @@ Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, return ExprError(); } -/// CheckConstCast - Check that a const_cast\(SrcExpr) is valid. -/// Refer to C++ 5.2.11 for details. const_cast is typically used in code -/// like this: -/// const char *str = "literal"; -/// legacy_function(const_cast\(str)); -void -CheckConstCast(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 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. - - 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); - - // 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(); - } - - // 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))) - { - 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(); - } -#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; - } -} - -/// CheckReinterpretCast - Check that a reinterpret_cast\(SrcExpr) is -/// valid. -/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code -/// like this: -/// char *bytes = reinterpret_cast\(int_ptr); -void -CheckReinterpretCast(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(x) has the - // same effect as the conversion *reinterpret_cast(&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(); - - DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); - SrcType = Self.Context.getPointerType(SrcType); - } 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; - } - 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; - 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; - } - - // 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; - } - 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; - } - - 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; - } - - // 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; - } - - // 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; - } - return; - } - - if (DestType->isFunctionPointerType()) { - // See above. - if (!Self.getLangOptions().CPlusPlus0x) { - Self.Diag(OpRange.getBegin(), diag::ext_reinterpret_cast_fn_obj) - << OpRange; - } - 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. -} - /// 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) @@ -434,385 +187,6 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType) !Self.IsQualificationConversion(SrcConstruct, DestConstruct); } -/// CheckStaticCast - Check that a static_cast\(SrcExpr) is valid. -/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making -/// implicit conversions explicit and getting rid of data loss warnings. -void -CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType, - const SourceRange &OpRange) -{ - // The order the tests is not entirely arbitrary. There is one conversion - // that can be handled in two different ways. Given: - // struct A {}; - // struct B : public A { - // B(); B(const A&); - // }; - // const A &a = B(); - // the cast static_cast(a) could be seen as either a static - // reference downcast, or an explicit invocation of the user-defined - // conversion using B's conversion constructor. - // DR 427 specifies that the downcast is to be applied here. - - // 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; - } - - // 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; - } - - // 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; - } - - // 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; - } - - // 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. - - // 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()); - - // 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->isComplexType() || SrcType->isVectorType()) { - // Fall through - these cannot be converted. - } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) { - return; - } - } - - // 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; - } - - // 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; - } - - // 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->getAsPointerType()) { - QualType SrcPointee = SrcPointer->getPointeeType(); - if (SrcPointee->isVoidType()) { - if (const PointerType *DestPointer = DestType->getAsPointerType()) { - QualType DestPointee = DestPointer->getPointeeType(); - 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; - } - return; - } - } - } - } - - // 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; -} - -/// Tests whether a conversion according to N2844 is valid. -TryStaticCastResult -TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) -{ - // 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; - - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) - return TSC_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. - 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; - } - - // FIXME: Similar to CheckReferenceInit, we actually need more AST annotation - // than nothing. - return TSC_Success; -} - -/// Tests whether a conversion according to C++ 5.2.9p5 is valid. -TryStaticCastResult -TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) -{ - // 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. - - if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) { - return TSC_NotApplicable; - } - - const ReferenceType *DestReference = DestType->getAsReferenceType(); - if (!DestReference) { - return TSC_NotApplicable; - } - QualType DestPointee = DestReference->getPointeeType(); - - return TryStaticDowncast(Self, SrcExpr->getType(), DestPointee, OpRange, - SrcExpr->getType(), DestType); -} - -/// Tests whether a conversion according to C++ 5.2.9p8 is valid. -TryStaticCastResult -TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange) -{ - // 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 *SrcPointer = SrcType->getAsPointerType(); - if (!SrcPointer) { - return TSC_NotApplicable; - } - - const PointerType *DestPointer = DestType->getAsPointerType(); - if (!DestPointer) { - return TSC_NotApplicable; - } - - return TryStaticDowncast(Self, SrcPointer->getPointeeType(), - DestPointer->getPointeeType(), - OpRange, SrcType, DestType); -} - -/// 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 -TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange, QualType OrigSrcType, - QualType OrigDestType) -{ - // Downcast can only happen in class hierarchies, so we need classes. - if (!DestType->isRecordType() || !SrcType->isRecordType()) { - return TSC_NotApplicable; - } - - BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false, - /*DetectVirtual=*/true); - if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { - return TSC_NotApplicable; - } - - // Target type does derive from source type. Now we're serious. If an error - // appears now, it's not ignored. - // This may not be entirely in line with the standard. Take for example: - // struct A {}; - // struct B : virtual A { - // B(A&); - // }; - // - // void f() - // { - // (void)static_cast(*((A*)0)); - // } - // As far as the standard is concerned, p5 does not apply (A is virtual), so - // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. - // However, both GCC and Comeau reject this example, and accepting it would - // mean more complex code if we're to preserve the nice error message. - // FIXME: Being 100% compliant here would be nice to have. - - // Must preserve cv, as always. - if (!DestType.isAtLeastAsQualifiedAs(SrcType)) { - Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away) - << "static_cast" << OrigDestType << OrigSrcType << OpRange; - return TSC_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. - Paths.clear(); - Paths.setRecordingPaths(true); - Self.IsDerivedFrom(DestType, SrcType, Paths); - std::string PathDisplayStr; - std::set DisplayedPaths; - for (BasePaths::paths_iterator Path = Paths.begin(); - Path != Paths.end(); ++Path) { - if (DisplayedPaths.insert(Path->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() + " -> "; - PathDisplayStr += DestType.getAsString(); - } - } - - Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) - << SrcType.getUnqualifiedType() << DestType.getUnqualifiedType() - << PathDisplayStr << OpRange; - return TSC_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; - } - - // FIXME: Test accessibility. - - return TSC_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 [...]. -/// -TryStaticCastResult -TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType, - const SourceRange &OpRange) -{ - const MemberPointerType *SrcMemPtr = SrcType->getAsMemberPointerType(); - if (!SrcMemPtr) - return TSC_NotApplicable; - const MemberPointerType *DestMemPtr = DestType->getAsMemberPointerType(); - if (!DestMemPtr) - return TSC_NotApplicable; - - // T == T, modulo cv - if (Self.Context.getCanonicalType( - SrcMemPtr->getPointeeType().getUnqualifiedType()) != - Self.Context.getCanonicalType(DestMemPtr->getPointeeType(). - getUnqualifiedType())) - return TSC_NotApplicable; - - // B base of D - QualType SrcClass(SrcMemPtr->getClass(), 0); - QualType DestClass(DestMemPtr->getClass(), 0); - BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false, - /*DetectVirtual=*/true); - if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { - return TSC_NotApplicable; - } - - // B is a base of D. But is it an allowed base? If not, it's a hard error. - if (Paths.isAmbiguous(DestClass)) { - Paths.clear(); - Paths.setRecordingPaths(true); - bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); - assert(StillOkay); - StillOkay = StillOkay; - std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); - Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) - << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; - return TSC_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; - } - - // FIXME: Test accessibility. - - return TSC_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 [...]. -TryStaticCastResult -TryStaticImplicitCast(Sema &Self, Expr *SrcExpr, QualType DestType, - const SourceRange &OpRange) -{ - 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; - } - if (DestType->isRecordType()) { - // FIXME: Use an implementation of C++ [over.match.ctor] for this. - return TSC_NotApplicable; - } - - // FIXME: To get a proper error from invalid conversions here, we need to - // reimplement more of this. - ImplicitConversionSequence ICS = Self.TryImplicitConversion( - SrcExpr, DestType); - return ICS.ConversionKind == ImplicitConversionSequence::BadConversion ? - TSC_NotApplicable : TSC_Success; -} - /// CheckDynamicCast - Check that a dynamic_cast\(SrcExpr) is valid. /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- /// checked downcasts in class hierarchies. @@ -844,7 +218,7 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, if (DestPointee->isVoidType()) { assert(DestPointer && "Reference to void is not possible"); } else if (DestRecord) { - if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, + if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, diag::err_bad_dynamic_cast_incomplete, DestRange)) return; @@ -873,7 +247,7 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, } 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; + << CT_Dynamic << OrigSrcType << OrigDestType << OpRange; } SrcPointee = SrcType; } else { @@ -901,7 +275,7 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType 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) - << "dynamic_cast" << OrigDestType << OrigSrcType << OpRange; + << CT_Dynamic << OrigSrcType << OrigDestType << OpRange; return; } @@ -930,3 +304,742 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType, // Done. Everything else is run-time checks. } + +/// CheckConstCast - Check that a const_cast\(SrcExpr) is valid. +/// Refer to C++ 5.2.11 for details. const_cast is typically used in code +/// like this: +/// const char *str = "literal"; +/// legacy_function(const_cast\(str)); +void +CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType, + const SourceRange &OpRange, const SourceRange &DestRange) +{ + if (!DestType->isLValueReferenceType()) + Self.DefaultFunctionArrayConversion(SrcExpr); + + 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; +} + +/// CheckReinterpretCast - Check that a reinterpret_cast\(SrcExpr) is +/// valid. +/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code +/// like this: +/// char *bytes = reinterpret_cast\(int_ptr); +void +CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType, + const SourceRange &OpRange, const SourceRange &DestRange) +{ + if (!DestType->isLValueReferenceType()) + Self.DefaultFunctionArrayConversion(SrcExpr); + + 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\(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 +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 {}; + // struct B : public A { + // B(); B(const A&); + // }; + // const A &a = B(); + // the cast static_cast(a) could be seen as either a static + // reference downcast, or an explicit invocation of the user-defined + // conversion using B's conversion constructor. + // DR 427 specifies that the downcast is to be applied here. + + // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". + // Done outside this function. + + TryCastResult tcr; + + // C++ 5.2.9p5, reference downcast. + // See the function for details. + // DR 427 specifies that this is to be applied before paragraph 2. + tcr = TryStaticReferenceDowncast(Self, SrcExpr, 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". + 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, [...]. + 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. + + QualType OrigSrcType = SrcExpr->getType(); + + QualType SrcType = Self.Context.getCanonicalType(SrcExpr->getType()); + + // 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->isComplexType() || SrcType->isVectorType()) { + // Fall through - these cannot be converted. + } 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. + 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. + 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 + // just the usual constness stuff. + if (const PointerType *SrcPointer = SrcType->getAsPointerType()) { + QualType SrcPointee = SrcPointer->getPointeeType(); + if (SrcPointee->isVoidType()) { + if (const PointerType *DestPointer = DestType->getAsPointerType()) { + QualType DestPointee = DestPointer->getPointeeType(); + if (DestPointee->isIncompleteOrObjectType()) { + // This is definitely the intended conversion, but it might fail due + // to a const violation. + if (!CStyle && !DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { + msg = diag::err_bad_cxx_cast_const_away; + return TC_Failed; + } + return TC_Success; + } + } + } + } + + // 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, + 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 TC_NotApplicable; + + if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) + 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) { + msg = diag::err_bad_lvalue_to_rvalue_cast; + return TC_Failed; + } + + // FIXME: Similar to CheckReferenceInit, we actually need more AST annotation + // than nothing. + 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, 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, + // 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->getAsReferenceType(); + if (!DestReference) { + 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, CStyle, + OpRange, SrcExpr->getType(), DestType, msg); +} + +/// Tests whether a conversion according to C++ 5.2.9p8 is valid. +TryCastResult +TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, + 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 + // 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->getAsPointerType(); + if (!DestPointer) { + 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(), 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. +TryCastResult +TryStaticDowncast(Sema &Self, QualType SrcType, QualType DestType, + 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 TC_NotApplicable; + } + + BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle, + /*DetectVirtual=*/true); + if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { + return TC_NotApplicable; + } + + // Target type does derive from source type. Now we're serious. If an error + // appears now, it's not ignored. + // This may not be entirely in line with the standard. Take for example: + // struct A {}; + // struct B : virtual A { + // B(A&); + // }; + // + // void f() + // { + // (void)static_cast(*((A*)0)); + // } + // As far as the standard is concerned, p5 does not apply (A is virtual), so + // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. + // However, both GCC and Comeau reject this example, and accepting it would + // mean more complex code if we're to preserve the nice error message. + // FIXME: Being 100% compliant here would be nice to have. + + // Must preserve cv, as always, unless we're in C-style mode. + if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { + msg = diag::err_bad_cxx_cast_const_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(DestType, SrcType, Paths); + } + std::string PathDisplayStr; + std::set DisplayedPaths; + 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 EI = PI->rbegin(),EE = PI->rend(); + EI != EE; ++EI) + PathDisplayStr += EI->Base->getType().getAsString() + " -> "; + PathDisplayStr += DestType.getAsString(); + } + } + + Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) + << SrcType.getUnqualifiedType() << DestType.getUnqualifiedType() + << PathDisplayStr << OpRange; + 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; + msg = 0; + return TC_Failed; + } + + if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType, + diag::err_downcast_from_inaccessible_base, Paths, + OpRange.getBegin(), DeclarationName())) { + msg = 0; + return TC_Failed; + } + + 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, QualType SrcType, QualType DestType, + bool CStyle, const SourceRange &OpRange, + unsigned &msg) +{ + const MemberPointerType *DestMemPtr = DestType->getAsMemberPointerType(); + if (!DestMemPtr) + 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 TC_NotApplicable; + + // B base of D + QualType SrcClass(SrcMemPtr->getClass(), 0); + QualType DestClass(DestMemPtr->getClass(), 0); + BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle, + /*DetectVirtual=*/true); + if (!Self.IsDerivedFrom(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(DestClass)) { + Paths.clear(); + Paths.setRecordingPaths(true); + bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); + assert(StillOkay); + StillOkay = 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 && Self.CheckBaseClassAccess(DestType, SrcType, + diag::err_downcast_from_inaccessible_base, Paths, + OpRange.getBegin(), DeclarationName())) { + msg = 0; + return TC_Failed; + } + + 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, Expr *SrcExpr, QualType DestType, + 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. + // 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()) { + // 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 ? + TC_NotApplicable : 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, 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++ 5.2.11p4: 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); + } + + // 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); + + // 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(); + } + + // Since we're dealing in canonical types, the remainder must be the same. + if (SrcType != DestType) + return TC_NotApplicable; + + 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; + } + + // C++ 5.2.10p10: [...] a reference cast reinterpret_cast(x) has the + // same effect as the conversion *reinterpret_cast(&x) with the + // built-in & and * operators. + // 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; + } + + // A valid member pointer cast. + return TC_Success; + } + + // 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; + } + + 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; + } + + 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; + } + + // 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; + } + + 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; + } + + if (!destIsPtr || !srcIsPtr) { + // With the valid non-pointer conversions out of the way, we can be even + // more stringent. + return TC_NotApplicable; + } + + // 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; +} diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp index 98d1f4c6af..458655868a 100644 --- a/lib/Sema/SemaExpr.cpp +++ b/lib/Sema/SemaExpr.cpp @@ -2919,14 +2919,15 @@ Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg initlist, /// CheckCastTypes - Check type constraints for casting between types. bool Sema::CheckCastTypes(SourceRange TyR, QualType castType, Expr *&castExpr) { + if (getLangOptions().CPlusPlus) + return CXXCheckCStyleCast(TyR, castType, castExpr); + UsualUnaryConversions(castExpr); // C99 6.5.4p2: the cast type needs to be void or scalar and the expression // type needs to be scalar. if (castType->isVoidType()) { // Cast to void allows any expr type. - } else if (castType->isDependentType() || castExpr->isTypeDependent()) { - // We can't check any more until template instantiation time. } else if (!castType->isScalarType() && !castType->isVectorType()) { if (Context.getCanonicalType(castType).getUnqualifiedType() == Context.getCanonicalType(castExpr->getType().getUnqualifiedType()) && @@ -3040,7 +3041,8 @@ Sema::ActOnCastExpr(SourceLocation LParenLoc, TypeTy *Ty, if (CheckCastTypes(SourceRange(LParenLoc, RParenLoc), castType, castExpr)) return ExprError(); - return Owned(new (Context) CStyleCastExpr(castType, castExpr, castType, + return Owned(new (Context) CStyleCastExpr(castType.getNonReferenceType(), + castExpr, castType, LParenLoc, RParenLoc)); } diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp index dc5f3e8e73..dc8d40b72d 100644 --- a/lib/Sema/SemaOverload.cpp +++ b/lib/Sema/SemaOverload.cpp @@ -1136,7 +1136,7 @@ bool Sema::isObjCPointerConversion(QualType FromType, QualType ToType, /// CheckPointerConversion - Check the pointer conversion from the /// expression From to the type ToType. This routine checks for -/// ambiguous (FIXME: or inaccessible) derived-to-base pointer +/// ambiguous or inaccessible derived-to-base pointer /// conversions for which IsPointerConversion has already returned /// true. It returns true and produces a diagnostic if there was an /// error, or returns false otherwise. diff --git a/test/Parser/cxx-ambig-paren-expr.cpp b/test/Parser/cxx-ambig-paren-expr.cpp index 1712d849d5..324f6b5f9f 100644 --- a/test/Parser/cxx-ambig-paren-expr.cpp +++ b/test/Parser/cxx-ambig-paren-expr.cpp @@ -5,9 +5,9 @@ void f() { int x, *px; // Type id. - (T())x; // expected-error {{used type 'T ()'}} - (T())+x; // expected-error {{used type 'T ()'}} - (T())*px; // expected-error {{used type 'T ()'}} + (T())x; // expected-error {{cast from 'int' to 'T ()'}} + (T())+x; // expected-error {{cast from 'int' to 'T ()'}} + (T())*px; // expected-error {{cast from 'int' to 'T ()'}} // Expression. x = (T()); diff --git a/test/SemaCXX/cstyle-cast.cpp b/test/SemaCXX/cstyle-cast.cpp new file mode 100644 index 0000000000..9c47df927e --- /dev/null +++ b/test/SemaCXX/cstyle-cast.cpp @@ -0,0 +1,231 @@ +// RUN: clang-cc -fsyntax-only -verify -faccess-control %s + +struct A {}; + +// ----------- const_cast -------------- + +typedef char c; +typedef c *cp; +typedef cp *cpp; +typedef cpp *cppp; +typedef cppp &cpppr; +typedef const cppp &cpppcr; +typedef const char cc; +typedef cc *ccp; +typedef volatile ccp ccvp; +typedef ccvp *ccvpp; +typedef const volatile ccvpp ccvpcvp; +typedef ccvpcvp *ccvpcvpp; +typedef int iar[100]; +typedef iar &iarr; +typedef int (*f)(int); + +void t_cc() +{ + ccvpcvpp var = 0; + // Cast away deep consts and volatiles. + char ***var2 = (cppp)(var); + char ***const &var3 = var2; + // Const reference to reference. + char ***&var4 = (cpppr)(var3); + // Drop reference. Intentionally without qualifier change. + char *** var5 = (cppp)(var4); + const int ar[100] = {0}; + // Array decay. Intentionally without qualifier change. + int *pi = (int*)(ar); + f fp = 0; + // Don't misidentify fn** as a function pointer. + f *fpp = (f*)(&fp); + int const A::* const A::*icapcap = 0; + int A::* A::* iapap = (int A::* A::*)(icapcap); +} + +// ----------- static_cast ------------- + +struct B : public A {}; // Single public base. +struct C1 : public virtual B {}; // Single virtual base. +struct C2 : public virtual B {}; +struct D : public C1, public C2 {}; // Diamond +struct E : private A {}; // Single private base. +struct F : public C1 {}; // Single path to B with virtual. +struct G1 : public B {}; +struct G2 : public B {}; +struct H : public G1, public G2 {}; // Ambiguous path to B. + +enum Enum { En1, En2 }; +enum Onom { On1, On2 }; + +struct Co1 { operator int(); }; +struct Co2 { Co2(int); }; +struct Co3 { }; +struct Co4 { Co4(Co3); operator Co3(); }; + +// Explicit implicits +void t_529_2() +{ + int i = 1; + (void)(float)(i); + double d = 1.0; + (void)(float)(d); + (void)(int)(d); + (void)(char)(i); + (void)(unsigned long)(i); + (void)(int)(En1); + (void)(double)(En1); + (void)(int&)(i); + (void)(const int&)(i); + + int ar[1]; + (void)(const int*)(ar); + (void)(void (*)())(t_529_2); + + (void)(void*)(0); + (void)(void*)((int*)0); + (void)(volatile const void*)((const int*)0); + (void)(A*)((B*)0); + (void)(A&)(*((B*)0)); + (void)(const B*)((C1*)0); + (void)(B&)(*((C1*)0)); + (void)(A*)((D*)0); + (void)(const A&)(*((D*)0)); + (void)(int B::*)((int A::*)0); + (void)(void (B::*)())((void (A::*)())0); + (void)(A*)((E*)0); // C-style cast ignores access control + (void)(void*)((const int*)0); // const_cast appended + + (void)(int)(Co1()); + (void)(Co2)(1); + (void)(Co3)((Co4)(Co3())); + + // Bad code below + //(void)(A*)((H*)0); // {{static_cast from 'struct H *' to 'struct A *' is not allowed}} +} + +// Anything to void +void t_529_4() +{ + (void)(1); + (void)(t_529_4); +} + +// Static downcasts +void t_529_5_8() +{ + (void)(B*)((A*)0); + (void)(B&)(*((A*)0)); + (void)(const G1*)((A*)0); + (void)(const G1&)(*((A*)0)); + (void)(B*)((const A*)0); // const_cast appended + (void)(B&)(*((const A*)0)); // const_cast appended + (void)(E*)((A*)0); // access control ignored + (void)(E&)(*((A*)0)); // access control ignored + + // Bad code below + + (void)(C1*)((A*)0); // expected-error {{cannot cast 'struct A *' to 'struct C1 *' via virtual base 'struct B'}} + (void)(C1&)(*((A*)0)); // expected-error {{cannot cast 'struct A' to 'struct C1 &' via virtual base 'struct B'}} + (void)(D*)((A*)0); // expected-error {{cannot cast 'struct A *' to 'struct D *' via virtual base 'struct B'}} + (void)(D&)(*((A*)0)); // expected-error {{cannot cast 'struct A' to 'struct D &' via virtual base 'struct B'}} + (void)(H*)((A*)0); // expected-error {{ambiguous cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} + (void)(H&)(*((A*)0)); // expected-error {{ambiguous cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} + + // TODO: Test DR427. This requires user-defined conversions, though. +} + +// Enum conversions +void t_529_7() +{ + (void)(Enum)(1); + (void)(Enum)(1.0); + (void)(Onom)(En1); + + // Bad code below + + (void)(Enum)((int*)0); // expected-error {{C-style cast from 'int *' to 'enum Enum' is not allowed}} +} + +// Void pointer to object pointer +void t_529_10() +{ + (void)(int*)((void*)0); + (void)(const A*)((void*)0); + (void)(int*)((const void*)0); // const_cast appended +} + +// Member pointer upcast. +void t_529_9() +{ + (void)(int A::*)((int B::*)0); + + // Bad code below + (void)(int A::*)((int H::*)0); // expected-error {{ambiguous conversion from pointer to member of derived class 'struct H'}} + (void)(int A::*)((int F::*)0); // expected-error {{conversion from pointer to member of class 'struct F'}} +} + +// -------- reinterpret_cast ----------- + +enum test { testval = 1 }; +struct structure { int m; }; +typedef void (*fnptr)(); + +// Test conversion between pointer and integral types, as in p3 and p4. +void integral_conversion() +{ + void *vp = (void*)(testval); + long l = (long)(vp); + (void)(float*)(l); + fnptr fnp = (fnptr)(l); + (void)(char)(fnp); // expected-error {{cast from pointer to smaller type 'char' loses information}} + (void)(long)(fnp); +} + +void pointer_conversion() +{ + int *p1 = 0; + float *p2 = (float*)(p1); + structure *p3 = (structure*)(p2); + typedef int **ppint; + ppint *deep = (ppint*)(p3); + (void)(fnptr*)(deep); +} + +void constness() +{ + int ***const ipppc = 0; + int const *icp = (int const*)(ipppc); + (void)(int*)(icp); // const_cast appended + int const *const **icpcpp = (int const* const**)(ipppc); // const_cast appended + int *ip = (int*)(icpcpp); + (void)(int const*)(ip); + (void)(int const* const* const*)(ipppc); +} + +void fnptrs() +{ + typedef int (*fnptr2)(int); + fnptr fp = 0; + (void)(fnptr2)(fp); + void *vp = (void*)(fp); + (void)(fnptr)(vp); +} + +void refs() +{ + long l = 0; + char &c = (char&)(l); + // Bad: from rvalue + (void)(int&)(&c); // expected-error {{C-style cast from rvalue to reference type 'int &'}} +} + +void memptrs() +{ + const int structure::*psi = 0; + (void)(const float structure::*)(psi); + (void)(int structure::*)(psi); // const_cast appended + + void (structure::*psf)() = 0; + (void)(int (structure::*)())(psf); + + (void)(void (structure::*)())(psi); // expected-error {{C-style cast from 'int const struct structure::*' to 'void (struct structure::*)()' is not allowed}} + (void)(int structure::*)(psf); // expected-error {{C-style cast from 'void (struct structure::*)()' to 'int struct structure::*' is not allowed}} +} diff --git a/test/SemaCXX/dcl_ambig_res.cpp b/test/SemaCXX/dcl_ambig_res.cpp index c392647a3b..495a6e6e42 100644 --- a/test/SemaCXX/dcl_ambig_res.cpp +++ b/test/SemaCXX/dcl_ambig_res.cpp @@ -50,7 +50,7 @@ void foo5() void foo6() { (void)(int(1)); //expression - (void)(int())1; // expected-error{{used type}} + (void)(int())1; // expected-error{{to 'int ()'}} } // [dcl.ambig.res]p7: diff --git a/test/SemaCXX/decl-expr-ambiguity.cpp b/test/SemaCXX/decl-expr-ambiguity.cpp index 05e25e9bb8..1b444c16cd 100644 --- a/test/SemaCXX/decl-expr-ambiguity.cpp +++ b/test/SemaCXX/decl-expr-ambiguity.cpp @@ -19,7 +19,7 @@ void f() { (int(1)); // expected-warning {{expression result unused}} // type-id - (int())1; // expected-error {{used type 'int ()' where arithmetic or pointer type is required}} + (int())1; // expected-error {{C-style cast from 'int' to 'int ()' is not allowed}} // Declarations. int fd(T(a)); // expected-warning {{parentheses were disambiguated as a function declarator}} diff --git a/test/SemaCXX/static-cast.cpp b/test/SemaCXX/static-cast.cpp index b5c515d5e1..8db8e33b93 100644 --- a/test/SemaCXX/static-cast.cpp +++ b/test/SemaCXX/static-cast.cpp @@ -1,11 +1,11 @@ -// RUN: clang-cc -fsyntax-only -verify %s +// RUN: clang-cc -fsyntax-only -verify -faccess-control %s struct A {}; struct B : public A {}; // Single public base. struct C1 : public virtual B {}; // Single virtual base. struct C2 : public virtual B {}; struct D : public C1, public C2 {}; // Diamond -struct E : private A {}; // Single private base. +struct E : private A {}; // Single private base. expected-note 2 {{'private' inheritance specifier here}} struct F : public C1 {}; // Single path to B with virtual. struct G1 : public B {}; struct G2 : public B {}; @@ -14,6 +14,11 @@ struct H : public G1, public G2 {}; // Ambiguous path to B. enum Enum { En1, En2 }; enum Onom { On1, On2 }; +struct Co1 { operator int(); }; +struct Co2 { Co2(int); }; +struct Co3 { }; +struct Co4 { Co4(Co3); operator Co3(); }; + // Explicit implicits void t_529_2() { @@ -45,7 +50,9 @@ void t_529_2() (void)static_cast((int A::*)0); (void)static_cast((void (A::*)())0); - // TODO: User-defined conversions + (void)static_cast(Co1()); + (void)static_cast(1); + (void)static_cast(static_cast(Co3())); // Bad code below @@ -80,11 +87,10 @@ void t_529_5_8() (void)static_cast(*((A*)0)); // expected-error {{cannot cast 'struct A' to 'struct D &' via virtual base 'struct B'}} (void)static_cast((const A*)0); // expected-error {{static_cast from 'struct A const *' to 'struct B *' casts away constness}} (void)static_cast(*((const A*)0)); // expected-error {{static_cast from 'struct A const' to 'struct B &' casts away constness}} - // Accessibility is not yet tested - //(void)static_cast((A*)0); // {{static_cast from 'struct A *' to 'struct E *' is not allowed}} - //(void)static_cast(*((A*)0)); // {{static_cast from 'struct A' to 'struct E &' is not allowed}} - (void)static_cast((A*)0); // expected-error {{ambiguous static_cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} - (void)static_cast(*((A*)0)); // expected-error {{ambiguous static_cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} + (void)static_cast((A*)0); // expected-error {{cannot cast 'struct A' to 'struct E' due to inaccessible}} + (void)static_cast(*((A*)0)); // expected-error {{cannot cast 'struct A' to 'struct E' due to inaccessible}} + (void)static_cast((A*)0); // expected-error {{ambiguous cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} + (void)static_cast(*((A*)0)); // expected-error {{ambiguous cast from base 'struct A' to derived 'struct H':\n struct A -> struct B -> struct G1 -> struct H\n struct A -> struct B -> struct G2 -> struct H}} (void)static_cast((B*)0); // expected-error {{static_cast from 'struct B *' to 'struct E *' is not allowed}} (void)static_cast(*((B*)0)); // expected-error {{non-const lvalue reference to type 'struct E' cannot be initialized with a value of type 'struct B'}} diff --git a/test/SemaTemplate/instantiate-cast.cpp b/test/SemaTemplate/instantiate-cast.cpp index d99f3e5566..d9088c8f6f 100644 --- a/test/SemaTemplate/instantiate-cast.cpp +++ b/test/SemaTemplate/instantiate-cast.cpp @@ -1,6 +1,6 @@ // RUN: clang-cc -fsyntax-only -verify %s -struct A { int x; }; +struct A { int x; }; // expected-note 2 {{candidate}} class Base { public: @@ -23,7 +23,7 @@ struct Constructible { template struct CStyleCast0 { void f(T t) { - (void)((U)t); // FIXME:ugly expected-error{{operand}} + (void)((U)t); // expected-error{{C-style cast from 'struct A' to 'int'}} } }; @@ -36,7 +36,7 @@ template struct CStyleCast0; // expected-note{{instantiation}} template struct StaticCast0 { void f(T t) { - (void)static_cast(t); // expected-error{{static_cast}} + (void)static_cast(t); // expected-error{{initialization of 'struct A'}} } }; @@ -89,7 +89,7 @@ template struct ConstCast0; // expected-note{{instantiatio template struct FunctionalCast1 { void f(T t) { - (void)U(t); // FIXME:ugly expected-error{{operand}} + (void)U(t); // expected-error{{C-style cast from 'struct A' to 'int'}} } }; diff --git a/www/cxx_status.html b/www/cxx_status.html index e6ac8ae98b..74edb9ce0d 100644 --- a/www/cxx_status.html +++ b/www/cxx_status.html @@ -540,10 +540,10 @@ welcome!

    5.2.3 [expr.type.conv] - - + + - Only between non-class types + Allows some invalid pointer conversions, AST has little information     5.2.4 [expr.pseudo] @@ -588,10 +588,10 @@ welcome!

    5.2.9 [expr.static.cast] - + - Some custom conversions don't work. + Allows some invalid pointer conversions, AST has little information     5.2.10 [expr.reinterpret.cast] @@ -694,10 +694,10 @@ welcome!

  5.4 [expr.cast] - - + + - Too lenient, and may not always have correct semantics + Allows some invalid pointer conversions, AST has little information   5.5 [expr.mptr.oper]