The problem here was that we were improperly treating
static_cast<std::remove_reference<T>::type&&>(x) as an lvalue because
the dereference was inside a NON_DEPENDENT_EXPR, which we always treat
as an lvalue. That seems like a bad assumption, but we can fix this bug
simply by moving the dereference outside.
Tested x86_64-pc-linux-gnu, applied to trunk and 4.5, will apply to 4.6
after 4.6.0.
commit 91300f260ac2bb684e62e28a1e63b8646d1d49cc
Author: Jason Merrill <ja...@redhat.com>
Date: Fri Mar 25 11:16:54 2011 +0100
PR c++/48289
* pt.c (build_non_dependent_expr): Keep dereferences outside the
NON_DEPENDENT_EXPR.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c8c1010..9032dd9 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18846,24 +18846,17 @@ build_non_dependent_expr (tree expr)
TREE_OPERAND (expr, 0),
build_non_dependent_expr (TREE_OPERAND (expr, 1)));
+ /* Keep dereferences outside the NON_DEPENDENT_EXPR so lvalue_kind
+ doesn't need to look inside. */
+ if (TREE_CODE (expr) == INDIRECT_REF && REFERENCE_REF_P (expr))
+ return convert_from_reference (build_non_dependent_expr
+ (TREE_OPERAND (expr, 0)));
+
/* If the type is unknown, it can't really be non-dependent */
gcc_assert (TREE_TYPE (expr) != unknown_type_node);
- /* Otherwise, build a NON_DEPENDENT_EXPR.
-
- REFERENCE_TYPEs are not stripped for expressions in templates
- because doing so would play havoc with mangling. Consider, for
- example:
-
- template <typename T> void f<T& g>() { g(); }
-
- In the body of "f", the expression for "g" will have
- REFERENCE_TYPE, even though the standard says that it should
- not. The reason is that we must preserve the syntactic form of
- the expression so that mangling (say) "f<g>" inside the body of
- "f" works out correctly. Therefore, the REFERENCE_TYPE is
- stripped here. */
- return build1 (NON_DEPENDENT_EXPR, non_reference (TREE_TYPE (expr)), expr);
+ /* Otherwise, build a NON_DEPENDENT_EXPR. */
+ return build1 (NON_DEPENDENT_EXPR, TREE_TYPE (expr), expr);
}
/* ARGS is a vector of expressions as arguments to a function call.
diff --git a/gcc/testsuite/g++.dg/cpp0x/move1.C
b/gcc/testsuite/g++.dg/cpp0x/move1.C
new file mode 100644
index 0000000..12e363a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/move1.C
@@ -0,0 +1,15 @@
+// { dg-options "-std=c++0x -pedantic-errors" }
+
+#include <utility>
+
+class A { };
+
+static void g ( A && ) { }
+
+template < class T > class B {
+public:
+ void f ( ) {
+ A a;
+ g ( std :: move ( a ) );
+ }
+};
