Index: include/clang/Basic/DiagnosticSemaKinds.td =================================================================== --- include/clang/Basic/DiagnosticSemaKinds.td +++ include/clang/Basic/DiagnosticSemaKinds.td @@ -5942,6 +5942,9 @@ def err_bad_lvalue_to_rvalue_cast : Error< "cannot cast from lvalue of type %1 to rvalue reference type %2; types are " "not compatible">; +def err_bad_rvalue_to_rvalue_cast : Error< + "cannot cast from rvalue reference of type %1 to rvalue reference type %2; types are " + "not compatible">; def err_bad_static_cast_pointer_nonpointer : Error< "cannot cast from type %1 to pointer type %2">; def err_bad_static_cast_member_pointer_nonmp : Error< Index: lib/Sema/SemaCast.cpp =================================================================== --- lib/Sema/SemaCast.cpp +++ lib/Sema/SemaCast.cpp @@ -1134,9 +1134,9 @@ } /// Tests whether a conversion according to N2844 is valid. -TryCastResult -TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, - bool CStyle, CastKind &Kind, CXXCastPath &BasePath, +TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, + QualType DestType, bool CStyle, + CastKind &Kind, CXXCastPath &BasePath, unsigned &msg) { // C++11 [expr.static.cast]p3: // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to @@ -1145,6 +1145,7 @@ if (!R) return TC_NotApplicable; + // FIXME C++1z doesn't allow this conversions for xvalues. if (!SrcExpr->isGLValue()) return TC_NotApplicable; @@ -1161,14 +1162,14 @@ ToType = ToType.getUnqualifiedType(); } - if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(), - ToType, FromType, - DerivedToBase, ObjCConversion, - ObjCLifetimeConversion) - != Sema::Ref_Compatible) { - if (CStyle) + Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( + SrcExpr->getLocStart(), ToType, FromType, DerivedToBase, ObjCConversion, + ObjCLifetimeConversion); + if (RefResult != Sema::Ref_Compatible) { + if (CStyle || RefResult == Sema::Ref_Incompatible) return TC_NotApplicable; - msg = diag::err_bad_lvalue_to_rvalue_cast; + msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast + : diag::err_bad_rvalue_to_rvalue_cast; return TC_Failed; } Index: test/CXX/expr/expr.post/expr.static.cast/p3-p4-0x.cpp =================================================================== --- /dev/null +++ test/CXX/expr/expr.post/expr.static.cast/p3-p4-0x.cpp @@ -0,0 +1,37 @@ +// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s +// expected-no-diagnostics + +// 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" (8.5.3). +// p4 +// Otherwise, an expression e can be explicitly converted to a type T using a +// static_cast of the form static_cast(e) if the declaration T t(e); is +// well-formed, for some invented temporary variable t (8.5). [...] +struct A { }; +struct B : A { }; + +struct C { explicit operator A&&(); }; +struct D { operator B(); }; + +template T& lvalue(); +template T&& xvalue(); +template T prvalue(); + +void test(A &a, B &b) { + A &&ar0 = static_cast(prvalue()); + A &&ar1 = static_cast(prvalue()); + A &&ar2 = static_cast(lvalue()); + A &&ar3 = static_cast(xvalue()); + A &&ar4 = static_cast(prvalue()); + A &&ar5 = static_cast(lvalue()); + A &&ar6 = static_cast(xvalue()); + A &&ar7 = static_cast(prvalue()); + + const A &&ar8 = static_cast(prvalue()); + const A &&ar9 = static_cast(prvalue()); + const A &&ar10 = static_cast(lvalue()); + const A &&ar11 = static_cast(xvalue()); + const A &&ar12 = static_cast(prvalue()); + const A &&ar13 = static_cast(lvalue()); +} Index: test/SemaCXX/rval-references.cpp =================================================================== --- test/SemaCXX/rval-references.cpp +++ test/SemaCXX/rval-references.cpp @@ -30,11 +30,15 @@ int &&virr2 = 0; int &&virr3 = virr2; // expected-error {{rvalue reference to type 'int' cannot bind to lvalue of type 'int'}} int i1 = 0; + const double d1 = 0; + const int ci1 = 1; int &&virr4 = i1; // expected-error {{rvalue reference to type 'int' cannot bind to lvalue of type 'int'}} int &&virr5 = ret_irr(); int &&virr6 = static_cast(i1); - (void)static_cast(i1); // expected-error {{types are not compatible}} - + (void)static_cast(i1); // expected-error {{reference to type 'not_int' could not bind to an lvalue of type 'int'}} + (void)static_cast(static_cast(i1)); // expected-error {{cannot cast from rvalue reference of type 'const int' to rvalue reference type 'int &&'}} + (void)static_cast(ci1); // expected-error {{types are not compatible}} + (void)static_cast(d1); int i2 = over(i1); not_int ni1 = over(0); int i3 = over(virr2);