re PR c++/49105 ([C++0x][SFINAE] ICE during list-initialization of rvalue-references to const)

	PR c++/49105
	* typeck.c (build_const_cast_1): Handle rvalue references.

From-SVN: r174092

gcc/cp/ChangeLog

 2011-05-23  Jason Merrill  <jason@redhat.com>
 
+	PR c++/49105
+	* typeck.c (build_const_cast_1): Handle rvalue references.
+
 	PR c++/47263
 	* decl.c (use_eh_spec_block): Do use an EH spec block for a
 	lambda op().

gcc/cp/typeck.c

@@ -6241,14 +6241,29 @@ build_const_cast_1 (tree dst_type, tree expr, tsubst_flags_t 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 & tf_error)
 	    error ("invalid const_cast of an rvalue of type %qT to type %qT",

gcc/testsuite/ChangeLog

 2011-05-23  Jason Merrill  <jason@redhat.com>
 
+	* g++.dg/cpp0x/rv-cast2.C: New.
+
 	* g++.dg/cpp0x/enum14.C: New.
 
 2011-05-23  Jakub Jelinek  <jakub@redhat.com>

gcc/testsuite/g++.dg/cpp0x/rv-cast2.C

+// 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>());
+}