#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,
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
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.
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:
// 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());
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
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,
// 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;
- }
+ // conversion as well.
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
// 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
// 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())) {
// 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();
}
}
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
/// 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.
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
///
/// 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;
}
projects / clang / commitdiff