re PR c/86453 (error: type variant differs by TYPE_PACKED in free_lang_data since r255469)

2018-07-12  Richard Biener  <rguenther@suse.de>

	PR c/86453
	* c-attribs.c (handle_packed_attribute): Do not build a variant
	type with TYPE_PACKED, instead ignore the attribute if we may
	not apply to the original type.

	* g++.dg/warn/pr86453.C: New testcase.

From-SVN: r262575

gcc/c-family/ChangeLog

+2018-07-12  Richard Biener  <rguenther@suse.de>
+
+	PR c/86453
+	* c-attribs.c (handle_packed_attribute): Do not build a variant
+	type with TYPE_PACKED, instead ignore the attribute if we may
+	not apply to the original type.
+
 2018-07-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/86443

gcc/c-family/c-attribs.c

@@ -502,8 +502,13 @@ handle_packed_attribute (tree *node, tree name, tree ARG_UNUSED (args),
   if (TYPE_P (*node))
     {
       if (!(flags & (int) ATTR_FLAG_TYPE_IN_PLACE))
-	*node = build_variant_type_copy (*node);
-      TYPE_PACKED (*node) = 1;
+	{
+	  warning (OPT_Wattributes,
+		   "%qE attribute ignored for type %qT", name, *node);
+	  *no_add_attrs = true;
+	}
+      else
+	TYPE_PACKED (*node) = 1;
     }
   else if (TREE_CODE (*node) == FIELD_DECL)
     {

gcc/testsuite/ChangeLog

 2018-07-12  Richard Biener  <rguenther@suse.de>
 
+	PR c/86453
+	* g++.dg/warn/pr86453.C: New testcase.
+
+2018-07-12  Richard Biener  <rguenther@suse.de>
+
 	PR middle-end/86479
 	* gcc.dg/graphite/pr86479.c: New testcase.
 

gcc/testsuite/g++.dg/warn/pr86453.C

+// { dg-do compile }
+// { dg-additional-options "-flto" { target lto } }
+struct X {
+  int *__attribute__((aligned(2), packed)) a; // { dg-warning "attribute ignored" }
+} b;