re PR c++/50512 (surprising change in overloading resolution)

	PR c++/50512
	* call.c (compare_ics): Only consider rvaluedness_matches_p
	if the target type is the same or it too differs in rvalueness.

From-SVN: r179208

gcc/cp/ChangeLog

 2011-09-26  Jason Merrill  <jason@redhat.com>
 
+	PR c++/50512
+	* call.c (compare_ics): Only consider rvaluedness_matches_p
+	if the target type is the same or it too differs in rvalueness.
+
 	PR c++/50523
 	* call.c (implicit_conversion): Mask out inappropriate LOOKUP
 	flags at the top of the function.

gcc/cp/call.c

@@ -7864,18 +7864,25 @@ compare_ics (conversion *ics1, conversion *ics2)
      types to which the references refer are the same type except for
      top-level cv-qualifiers, and the type to which the reference
      initialized by S2 refers is more cv-qualified than the type to
-     which the reference initialized by S1 refers */
+     which the reference initialized by S1 refers.
+
+     DR 1328 [over.match.best]: the context is an initialization by
+     conversion function for direct reference binding (13.3.1.6) of a
+     reference to function type, the return type of F1 is the same kind of
+     reference (i.e. lvalue or rvalue) as the reference being initialized,
+     and the return type of F2 is not.  */
 
   if (ref_conv1 && ref_conv2)
     {
-      if (!ref_conv1->this_p && !ref_conv2->this_p)
+      if (!ref_conv1->this_p && !ref_conv2->this_p
+	  && (ref_conv1->rvaluedness_matches_p
+	      != ref_conv2->rvaluedness_matches_p)
+	  && (same_type_p (ref_conv1->type, ref_conv2->type)
+	      || (TYPE_REF_IS_RVALUE (ref_conv1->type)
+		  != TYPE_REF_IS_RVALUE (ref_conv2->type))))
 	{
-	  if (ref_conv1->rvaluedness_matches_p
-	      > ref_conv2->rvaluedness_matches_p)
-	    return 1;
-	  if (ref_conv2->rvaluedness_matches_p
-	      > ref_conv1->rvaluedness_matches_p)
-	    return -1;
+	  return (ref_conv1->rvaluedness_matches_p
+		  - ref_conv2->rvaluedness_matches_p);
 	}
 
       if (same_type_ignoring_top_level_qualifiers_p (to_type1, to_type2))

gcc/testsuite/ChangeLog

 2011-09-26  Jason Merrill  <jason@redhat.com>
 
+	PR c++/50512
+	* g++.dg/overload/rvalue3.C: New.
+
 	PR c++/50523
 	* g++.dg/overload/ref-conv2.C: New.
 

gcc/testsuite/g++.dg/overload/rvalue3.C

+// PR c++/50512
+
+void foo (const char *const& s);
+template<typename C> void foo (const C& x) { x.a; }
+
+void f () {
+  foo ("abc");
+}