re PR c++/61392 (internal compiler error: in write_template_arg_literal, at cp/mangle.c:3072)

	PR c++/61392
	* mangle.c (write_expression): Use unresolved-name mangling for
	DR850 case.

From-SVN: r215414

gcc/cp/ChangeLog

 2014-09-19  Jason Merrill  <jason@redhat.com>
 
+	PR c++/61392
+	* mangle.c (write_expression): Use unresolved-name mangling for
+	DR850 case.
+
 	PR c++/61465
 	* call.c (convert_like_real) [ck_identity]: Call mark_rvalue_use
 	after pulling out an element from a CONSTRUCTOR.

gcc/cp/mangle.c

@@ -2861,11 +2861,16 @@ write_expression (tree expr)
 	    {
 	      write_string (operator_name_info[(int)code].mangled_name);
 	      ob = TREE_OPERAND (ob, 0);
+	      write_expression (ob);
 	    }
-	  else
-	    write_string ("dt");
+	  else if (!is_dummy_object (ob))
+	    {
+	      write_string ("dt");
+	      write_expression (ob);
+	    }
+	  /* else, for a non-static data member with no associated object (in
+	     unevaluated context), use the unresolved-name mangling.  */
 
-	  write_expression (ob);
 	  write_member_name (TREE_OPERAND (expr, 1));
 	  return;
 	}

gcc/cp/semantics.c

@@ -1685,7 +1685,7 @@ finish_non_static_data_member (tree decl, tree object, tree qualifying_scope)
   if (object == error_mark_node)
     return error_mark_node;
 
-  /* DR 613: Can use non-static data members without an associated
+  /* DR 613/850: Can use non-static data members without an associated
      object in sizeof/decltype/alignof.  */
   if (is_dummy_object (object) && cp_unevaluated_operand == 0
       && (!processing_template_decl || !current_class_ref))

gcc/testsuite/g++.dg/abi/mangle63.C

+// DR 850 makes this valid
+// { dg-do compile { target c++11 } }
+
+template<class T> struct A
+{
+  int mem;
+  template<class U> decltype(U()+mem) f();
+};
+int i = A<int>().f<int>();
+
+// { dg-final { scan-assembler "_ZN1AIiE1fIiEEDTplcvT__E3memEv" } }