re PR c/24255 (__transparent_union__ mishandled)

        PR c/24255
        * tree.h (DECL_TRANSPARENT_UNION): Remove.
        * function.c (assign_parm_find_data_types): Don't support it.
        * print-tree.c (print_node): Likewise.
        * c-common.c (handle_transparent_union_attribute): Likewise.
        Use build_duplicate_type.
        * tree-inline.c (remap_type_1): Split out of remap_type;
        properly remap aggregate fields.
        (build_duplicate_type): New.
        * doc/extend.texi (Variable Attributes): Remove documentation
        for transparent_union.

From-SVN: r105338

1 files changed, 27 insertions, 23 deletions

diff --git a/gcc/c-common.c b/gcc/c-common.c
index 4114fbf2b19..c5b409e77c0 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -4309,39 +4309,43 @@ handle_transparent_union_attribute (tree *node, tree name,
 				    tree ARG_UNUSED (args), int flags,
 				    bool *no_add_attrs)
 {
-  tree decl = NULL_TREE;
-  tree *type = NULL;
-  int is_type = 0;
+  tree type = NULL;
+
+  *no_add_attrs = true;
 
   if (DECL_P (*node))
     {
-      decl = *node;
-      type = &TREE_TYPE (decl);
-      is_type = TREE_CODE (*node) == TYPE_DECL;
+      if (TREE_CODE (*node) != TYPE_DECL)
+	goto ignored;
+      node = &TREE_TYPE (*node);
+      type = *node;
     }
   else if (TYPE_P (*node))
-    type = node, is_type = 1;
+    type = *node;
+  else
+    goto ignored;
 
-  if (is_type
-      && TREE_CODE (*type) == UNION_TYPE
-      && (decl == 0
-	  || (TYPE_FIELDS (*type) != 0
-	      && TYPE_MODE (*type) == DECL_MODE (TYPE_FIELDS (*type)))))
+  if (TREE_CODE (type) == UNION_TYPE)
     {
+      /* When IN_PLACE is set, leave the check for FIELDS and MODE to
+	 the code in finish_struct.  */
       if (!(flags & (int) ATTR_FLAG_TYPE_IN_PLACE))
-	*type = build_variant_type_copy (*type);
-      TYPE_TRANSPARENT_UNION (*type) = 1;
-    }
-  else if (decl != 0 && TREE_CODE (decl) == PARM_DECL
-	   && TREE_CODE (*type) == UNION_TYPE
-	   && TYPE_MODE (*type) == DECL_MODE (TYPE_FIELDS (*type)))
-    DECL_TRANSPARENT_UNION (decl) = 1;
-  else
-    {
-      warning (OPT_Wattributes, "%qE attribute ignored", name);
-      *no_add_attrs = true;
+	{
+	  if (TYPE_FIELDS (type) == NULL_TREE
+	      || TYPE_MODE (type) != DECL_MODE (TYPE_FIELDS (type)))
+	    goto ignored;
+
+	  /* A type variant isn't good enough, since we don't a cast
+	     to such a type removed as a no-op.  */
+	  *node = type = build_duplicate_type (type);
+	}
+
+      TYPE_TRANSPARENT_UNION (type) = 1;
+      return NULL_TREE;
     }
 
+ ignored:
+  warning (OPT_Wattributes, "%qE attribute ignored", name);
   return NULL_TREE;
 }