/// 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);
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, CastExpr::CastKind &Kind)
{
// 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,
Kind, msg)
!= TC_Success && msg != 0)
Self.Diag(OpRange.getBegin(), msg) << CT_Static
<< 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)
{
// The order the tests is not entirely arbitrary. There is one conversion
// that can be handled in two different ways. Given:
// struct A {};
// struct B : public A {
// B(); B(const A&);
// };
// const A &a = B();
// the cast static_cast<const B&>(a) could be seen as either a static
// reference downcast, or an explicit invocation of the user-defined
// conversion using B's conversion constructor.
// DR 427 specifies that the downcast is to be applied here.
// 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;
}
/// 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)
{
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();
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.
}
/// 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)
{
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;
}
}
