DR 1571

	DR 1571
	* call.c (reference_binding): Recurse on user-defined conversion.

From-SVN: r209521

gcc/cp/ChangeLog

 2014-04-18  Jason Merrill  <jason@redhat.com>
 
+	DR 1571
+	* call.c (reference_binding): Recurse on user-defined conversion.
+
 	PR c++/60872
 	* call.c (standard_conversion): Don't try to apply restrict to void.
 

gcc/cp/call.c

@@ -1684,20 +1684,30 @@ reference_binding (tree rto, tree rfrom, tree expr, bool c_cast_p, int flags,
   if (!conv)
     return NULL;
 
+  if (conv->user_conv_p)
+    {
+      /* If initializing the temporary used a conversion function,
+	 recalculate the second conversion sequence.  */
+      for (conversion *t = conv; t; t = next_conversion (t))
+	if (t->kind == ck_user
+	    && DECL_CONV_FN_P (t->cand->fn))
+	  {
+	    tree ftype = TREE_TYPE (TREE_TYPE (t->cand->fn));
+	    int sflags = (flags|LOOKUP_NO_CONVERSION)&~LOOKUP_NO_TEMP_BIND;
+	    conversion *new_second
+	      = reference_binding (rto, ftype, NULL_TREE, c_cast_p,
+				   sflags, complain);
+	    if (!new_second)
+	      return NULL;
+	    return merge_conversion_sequences (t, new_second);
+	  }
+    }
+
   conv = build_conv (ck_ref_bind, rto, conv);
   /* This reference binding, unlike those above, requires the
      creation of a temporary.  */
   conv->need_temporary_p = true;
-  if (TYPE_REF_IS_RVALUE (rto))
-    {
-      conv->rvaluedness_matches_p = 1;
-      /* In the second case, if the reference is an rvalue reference and
-	 the second standard conversion sequence of the user-defined
-	 conversion sequence includes an lvalue-to-rvalue conversion, the
-	 program is ill-formed.  */
-      if (conv->user_conv_p && next_conversion (conv)->kind == ck_rvalue)
-	conv->bad_p = 1;
-    }
+  conv->rvaluedness_matches_p = TYPE_REF_IS_RVALUE (rto);
 
   return conv;
 }

gcc/testsuite/g++.dg/cpp0x/overload3.C

@@ -13,5 +13,5 @@ struct wrap
 int main()
 {
   wrap w;
-  f(w);				// { dg-error "lvalue" }
+  f(w);				// { dg-error "" }
 }

gcc/testsuite/g++.dg/cpp0x/rv-init1.C

+// Core DR 1604/1571/1572
+// { dg-require-effective-target c++11 }
+
+struct Banana { };
+struct Enigma { operator const Banana(); };
+struct Doof { operator Banana&(); };
+void enigmatic() {
+  typedef const Banana ConstBanana;
+  Banana &&banana1 = ConstBanana(); // { dg-error "" }
+  Banana &&banana2 = Enigma();      // { dg-error "" }
+  Banana &&banana3 = Doof();        // { dg-error "" }
+}
+
+class A {
+public:
+  operator volatile int &();
+};
+A a;
+
+const int & ir1a = a.operator volatile int&(); // { dg-error "" }
+const int & ir2a = a;			       // { dg-error "" }
+
+struct X {
+  operator int&();
+} x;
+int&& rri2 = X();		// { dg-error "" }