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Teach static_cast and dynamic_cast about rvalue references. 

llvm-svn: 124006
This commit is contained in:
Douglas Gregor 2011-01-22 00:06:57 +00:00
parent 3f9047e321
commit 465184ae10
3 changed files with 51 additions and 13 deletions
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26
clang/lib/Sema/SemaCXXCast.cpp
View File

@ -341,7 +341,9 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
DestPointee = DestPointer->getPointeeType();
} else if ((DestReference = DestType->getAs<ReferenceType>())) {
DestPointee = DestReference->getPointeeType();
VK = isa<LValueReferenceType>(DestReference) ? VK_LValue : VK_RValue;
VK = isa<LValueReferenceType>(DestReference) ? VK_LValue
: isa<RValueReferenceType>(DestReference) ? VK_XValue
: VK_RValue;
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
<< OrigDestType << DestRange;
@ -364,10 +366,8 @@ CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
// 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,
// [...]
// an lvalue of a complete class type, [...]. If T is an rvalue reference
// type, v shall be an expression having a complete class type, [...]
QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
QualType SrcPointee;
if (DestPointer) {
@ -578,8 +578,9 @@ static TryCastResult TryStaticCast(Sema &Self, Expr *&SrcExpr,
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".
// C++0x [expr.static.cast]p3:
// A glvalue 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) {
Kind = CK_NoOp;
@ -695,13 +696,14 @@ static TryCastResult TryStaticCast(Sema &Self, Expr *&SrcExpr,
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".
// C++0x [expr.static.cast]p3:
// A glvalue 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->getAs<RValueReferenceType>();
if (!R)
return TC_NotApplicable;
if (!SrcExpr->isLValue())
if (!SrcExpr->isGLValue())
return TC_NotApplicable;
// Because we try the reference downcast before this function, from now on
@ -710,15 +712,13 @@ TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType,
bool DerivedToBase;
bool ObjCConversion;
if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(),
SrcExpr->getType(), R->getPointeeType(),
R->getPointeeType(), SrcExpr->getType(),
DerivedToBase, ObjCConversion) <
Sema::Ref_Compatible_With_Added_Qualification) {
msg = diag::err_bad_lvalue_to_rvalue_cast;
return TC_Failed;
}
// FIXME: We should probably have an AST node for lvalue-to-rvalue
// conversions.
return TC_Success;
}

14
clang/test/CXX/expr/expr.post/expr.dynamic.cast/p3-0x.cpp Normal file
View File

@ -0,0 +1,14 @@
// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
struct X { virtual ~X(); };
struct Y : public X { };
struct Z; // expected-note{{forward declaration of 'Z'}}
void test(X &x, Y &y, Z &z) {
// If T is an rvalue reference type, v shall be an expression having
// a complete class type, and the result is an xvalue of the type
// referred to by T.
Y &&yr0 = dynamic_cast<Y&&>(x);
Y &&yr1 = dynamic_cast<Y&&>(static_cast<X&&>(x));
Y &&yr2 = dynamic_cast<Y&&>(z); // expected-error{{'Z' is an incomplete type}}
}

24
clang/test/CXX/expr/expr.post/expr.static.cast/p3-0x.cpp Normal file
View File

@ -0,0 +1,24 @@
// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
// A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
// cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1" (8.5.3).
struct A { };
struct B : A { };
template<typename T> T& lvalue();
template<typename T> T&& xvalue();
void test(A &a, B &b) {
A &&ar0 = static_cast<A&&>(a);
A &&ar1 = static_cast<A&&>(b);
A &&ar2 = static_cast<A&&>(lvalue<A>());
A &&ar3 = static_cast<A&&>(lvalue<B>());
A &&ar4 = static_cast<A&&>(xvalue<A>());
A &&ar5 = static_cast<A&&>(xvalue<B>());
const A &&ar6 = static_cast<const A&&>(a);
const A &&ar7 = static_cast<const A&&>(b);
const A &&ar8 = static_cast<const A&&>(lvalue<A>());
const A &&ar9 = static_cast<const A&&>(lvalue<B>());
const A &&ar10 = static_cast<const A&&>(xvalue<A>());
const A &&ar11 = static_cast<const A&&>(xvalue<B>());
}