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Update const_cast semantics for rvalue references. Add tests for 

reinterpret_cast and const_cast using rvalue references.

llvm-svn: 124007
This commit is contained in:
Douglas Gregor 2011-01-22 00:19:52 +00:00
parent 465184ae10
commit c1ed20cfba
3 changed files with 37 additions and 5 deletions
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9
clang/lib/Sema/SemaCXXCast.cpp
View File

@ -1050,9 +1050,8 @@ 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->getAs<LValueReferenceType>()) {
if (!SrcExpr->isLValue()) {
if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) {
// 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.
@ -1156,8 +1155,8 @@ static TryCastResult TryReinterpretCast(Sema &Self, Expr *SrcExpr,
if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
bool LValue = DestTypeTmp->isLValueReferenceType();
if (LValue && !SrcExpr->isLValue()) {
// Cannot cast non-lvalue to reference type. See the similar comment in
// const_cast.
// Cannot cast non-lvalue to lvalue reference type. See the similar
// comment in const_cast.
msg = diag::err_bad_cxx_cast_rvalue;
return TC_NotApplicable;
}

17
clang/test/CXX/expr/expr.post/expr.const.cast/p1-0x.cpp Normal file
View File

@ -0,0 +1,17 @@
// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
// The result of the expression const_cast<T>(v) is of type T. If T is
// an lvalue reference to object type, the result is an lvalue; if T
// is an rvalue reference to object type, the result is an xvalue;.
unsigned int f(int);
template<typename T> T& lvalue();
template<typename T> T&& xvalue();
template<typename T> T prvalue();
void test_classification(const int *ptr) {
int *ptr0 = const_cast<int *&&>(ptr);
int *ptr1 = const_cast<int *&&>(xvalue<const int*>());
int *ptr2 = const_cast<int *&&>(prvalue<const int*>());
}

16
clang/test/CXX/expr/expr.post/expr.reinterpret.cast/p1-0x.cpp Normal file
View File

@ -0,0 +1,16 @@
// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
// If T is an lvalue reference type or an rvalue reference to function
// type, the result is an lvalue; if T is an rvalue reference to
// object type, the result is an xvalue;
unsigned int f(int);
template<typename T> T&& xvalue();
void test_classification(char *ptr) {
int (&fr0)(int) = reinterpret_cast<int (&&)(int)>(f);
int &&ir0 = reinterpret_cast<int &&>(*ptr);
int &&ir1 = reinterpret_cast<int &&>(0);
int &&ir2 = reinterpret_cast<int &&>('a');
int &&ir3 = reinterpret_cast<int &&>(xvalue<char>());
}