From 64c58ffe439f284f8ff22900f2bbd4923e92d835 Mon Sep 17 00:00:00 2001
From: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 25 May 2011 01:08:38 +0000
Subject: [PATCH] 	PR c++/49105
 	* typeck.c (build_const_cast_1): Handle rvalue references.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@174162 138bc75d-0d04-0410-961f-82ee72b054a4

index 9a81ea5..578eb83 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -6220,14 +6220,29 @@ build_const_cast_1 (tree dst_type, tree expr, bool complain,
 
   /* [expr.const.cast]
 
-     An lvalue of type T1 can be explicitly converted to an lvalue of
-     type T2 using the cast const_cast<T2&> (where T1 and T2 are object
-     types) if a pointer to T1 can be explicitly converted to the type
-     pointer to T2 using a const_cast.  */
+     For two object types T1 and T2, if a pointer to T1 can be explicitly
+     converted to the type "pointer to T2" using a const_cast, then the
+     following conversions can also be made:
+
+     -- an lvalue of type T1 can be explicitly converted to an lvalue of
+     type T2 using the cast const_cast<T2&>;
+
+     -- a glvalue of type T1 can be explicitly converted to an xvalue of
+     type T2 using the cast const_cast<T2&&>; and
+
+     -- if T1 is a class type, a prvalue of type T1 can be explicitly
+     converted to an xvalue of type T2 using the cast const_cast<T2&&>.  */
+
   if (TREE_CODE (dst_type) == REFERENCE_TYPE)
     {
       reference_type = dst_type;
-      if (! real_lvalue_p (expr))
+      if (!TYPE_REF_IS_RVALUE (dst_type)
+	  ? real_lvalue_p (expr)
+	  : (CLASS_TYPE_P (TREE_TYPE (dst_type))
+	     ? lvalue_p (expr)
+	     : lvalue_or_rvalue_with_address_p (expr)))
+	/* OK.  */;
+      else
 	{
 	  if (complain)
 	    error ("invalid const_cast of an rvalue of type %qT to type %qT",
new file mode 100644
index 0000000..94ee4ca
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/rv-cast2.C
@@ -0,0 +1,21 @@
+// Test for const_cast to reference (5.2.11/4).
+// { dg-options -std=c++0x }
+
+template <class T> T&& xval();
+template <class T> T& lval();
+template <class T> T prval();
+
+struct A { };
+
+int main()
+{
+  const_cast<int&>(lval<int>());
+  const_cast<int&>(xval<int>());   // { dg-error "" }
+  const_cast<int&>(prval<int>());  // { dg-error "" }
+  const_cast<int&&>(lval<int>());
+  const_cast<int&&>(xval<int>());
+  const_cast<int&&>(prval<int>()); // { dg-error "" }
+  const_cast<A&&>(lval<A>());
+  const_cast<A&&>(xval<A>());
+  const_cast<A&&>(prval<A>());
+}
-- 
1.7.0.4