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A small error message improvement and some comment cleanup for static_cast. 

llvm-svn: 58762
This commit is contained in:
Sebastian Redl 2008-11-05 17:54:26 +00:00
parent 87002dbea1
commit 6a43b1c435
2 changed files with 28 additions and 14 deletions
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40
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -340,12 +340,18 @@ void
Sema::CheckStaticCast(Expr *&SrcExpr, QualType DestType,
const SourceRange &OpRange)
{
// Conversions are tried roughly in the order the standard specifies them.
// This is necessary because there are some conversions that can be
// interpreted in more than one way, and the order disambiguates.
// DR 427 specifies that paragraph 5 is to be applied before paragraph 2.
// 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.
// This option is unambiguous and simple, so put it here.
// C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
if (DestType->isVoidType()) {
return;
@ -353,6 +359,7 @@ Sema::CheckStaticCast(Expr *&SrcExpr, QualType DestType,
// C++ 5.2.9p5, reference downcast.
// See the function for details.
// DR 427 specifies that this is to be applied before paragraph 2.
if (IsStaticReferenceDowncast(SrcExpr, DestType)) {
return;
}
@ -361,15 +368,17 @@ Sema::CheckStaticCast(Expr *&SrcExpr, QualType DestType,
// [...] if the declaration "T t(e);" is well-formed, [...].
ImplicitConversionSequence ICS = TryDirectInitialization(SrcExpr, DestType);
if (ICS.ConversionKind != ImplicitConversionSequence::BadConversion) {
if (ICS.ConversionKind == ImplicitConversionSequence::StandardConversion &&
ICS.Standard.First != ICK_Identity)
{
assert(ICS.ConversionKind != ImplicitConversionSequence::EllipsisConversion
&& "Direct initialization cannot result in ellipsis conversion");
// UserDefinedConversionSequence has a StandardConversionSequence as a
// prefix. Accessing Standard is therefore safe.
// FIXME: Of course, this is definitely not enough.
if(ICS.Standard.First != ICK_Identity) {
DefaultFunctionArrayConversion(SrcExpr);
}
// FIXME: Test the details, such as accessible base.
return;
}
// FIXME: Missing the validation of the conversion, e.g. for an accessible
// base.
// C++ 5.2.9p6: May apply the reverse of any standard conversion, except
// lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
@ -419,9 +428,14 @@ Sema::CheckStaticCast(Expr *&SrcExpr, QualType DestType,
if (SrcPointee->isVoidType()) {
if (const PointerType *DestPointer = DestType->getAsPointerType()) {
QualType DestPointee = DestPointer->getPointeeType();
if (DestPointee->isObjectType() &&
DestPointee.isAtLeastAsQualifiedAs(SrcPointee))
{
if (DestPointee->isObjectType()) {
// This is definitely the intended conversion, but it might fail due
// to a const violation.
if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away,
"static_cast", DestType.getAsString(),
OrigSrcType.getAsString(), OpRange);
}
return;
}
}

2
clang/test/SemaCXX/static-cast.cpp
View File

@ -113,7 +113,7 @@ void t_529_10()
// Bad code below
(void)static_cast<int*>((const void*)0); // expected-error {{static_cast from 'void const *' to 'int *' is not allowed}}
(void)static_cast<int*>((const void*)0); // expected-error {{static_cast from 'void const *' to 'int *' casts away constness}}
(void)static_cast<void (*)()>((void*)0); // expected-error {{static_cast from 'void *' to 'void (*)(void)' is not allowed}}
}