Implement C++0x unrestricted unions (N2544)

	Implement C++0x unrestricted unions (N2544)
	* class.c (check_field_decl): Loosen union handling in C++0x.
	* method.c (walk_field_subobs): Split out from...
	(synthesized_method_walk): ...here.  Set msg before loops.
	(process_subob_fn): Check for triviality in union members.
	* init.c (sort_mem_initializers): Splice out uninitialized
	anonymous unions and union members.
	(push_base_cleanups): Don't automatically destroy anonymous unions
	and union members.

From-SVN: r162187

1 files changed, 41 insertions, 12 deletions

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 20f921d..4e7cab3 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -708,23 +708,34 @@ sort_mem_initializers (tree t, tree mem_inits)
 
      If a ctor-initializer specifies more than one mem-initializer for
      multiple members of the same union (including members of
-     anonymous unions), the ctor-initializer is ill-formed.  */
+     anonymous unions), the ctor-initializer is ill-formed.
+
+     Here we also splice out uninitialized union members.  */
   if (uses_unions_p)
     {
       tree last_field = NULL_TREE;
-      for (init = sorted_inits; init; init = TREE_CHAIN (init))
+      tree *p;
+      for (p = &sorted_inits; *p; )
 	{
 	  tree field;
 	  tree field_type;
 	  int done;
 
-	  /* Skip uninitialized members and base classes.  */
-	  if (!TREE_VALUE (init)
-	      || TREE_CODE (TREE_PURPOSE (init)) != FIELD_DECL)
-	    continue;
+	  init = *p;
+
+	  field = TREE_PURPOSE (init);
+
+	  /* Skip base classes.  */
+	  if (TREE_CODE (field) != FIELD_DECL)
+	    goto next;
+
+	  /* If this is an anonymous union with no explicit initializer,
+	     splice it out.  */
+	  if (!TREE_VALUE (init) && ANON_UNION_TYPE_P (TREE_TYPE (field)))
+	    goto splice;
+
 	  /* See if this field is a member of a union, or a member of a
 	     structure contained in a union, etc.  */
-	  field = TREE_PURPOSE (init);
 	  for (field_type = DECL_CONTEXT (field);
 	       !same_type_p (field_type, t);
 	       field_type = TYPE_CONTEXT (field_type))
@@ -732,14 +743,19 @@ sort_mem_initializers (tree t, tree mem_inits)
 	      break;
 	  /* If this field is not a member of a union, skip it.  */
 	  if (TREE_CODE (field_type) != UNION_TYPE)
-	    continue;
+	    goto next;
+
+	  /* If this union member has no explicit initializer, splice
+	     it out.  */
+	  if (!TREE_VALUE (init))
+	    goto splice;
 
 	  /* It's only an error if we have two initializers for the same
 	     union type.  */
 	  if (!last_field)
 	    {
 	      last_field = field;
-	      continue;
+	      goto next;
 	    }
 
 	  /* See if LAST_FIELD and the field initialized by INIT are
@@ -785,6 +801,13 @@ sort_mem_initializers (tree t, tree mem_inits)
 	  while (!done);
 
 	  last_field = field;
+
+	next:
+	  p = &TREE_CHAIN (*p);
+	  continue;
+	splice:
+	  *p = TREE_CHAIN (*p);
+	  continue;
 	}
     }
 
@@ -3353,21 +3376,27 @@ push_base_cleanups (void)
       finish_decl_cleanup (NULL_TREE, expr);
     }
 
+  /* Don't automatically destroy union members.  */
+  if (TREE_CODE (current_class_type) == UNION_TYPE)
+    return;
+
   for (member = TYPE_FIELDS (current_class_type); member;
        member = TREE_CHAIN (member))
     {
-      if (TREE_TYPE (member) == error_mark_node
+      tree this_type = TREE_TYPE (member);
+      if (this_type == error_mark_node
 	  || TREE_CODE (member) != FIELD_DECL
 	  || DECL_ARTIFICIAL (member))
 	continue;
-      if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (member)))
+      if (ANON_UNION_TYPE_P (this_type))
+	continue;
+      if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (this_type))
 	{
 	  tree this_member = (build_class_member_access_expr
 			      (current_class_ref, member,
 			       /*access_path=*/NULL_TREE,
 			       /*preserve_reference=*/false,
 			       tf_warning_or_error));
-	  tree this_type = TREE_TYPE (member);
 	  expr = build_delete (this_type, this_member,
 			       sfk_complete_destructor,
 			       LOOKUP_NONVIRTUAL|LOOKUP_DESTRUCTOR|LOOKUP_NORMAL,