tree.h (tree_common): Note front-end dependencies on layout of this structure.

        * tree.h (tree_common): Note front-end dependencies on layout of
        this structure.

From-SVN: r21118

gcc/ChangeLog

+Mon Jul 13 23:26:43 1998  Jeffrey A Law  (law@cygnus.com)
+
+	* tree.h (tree_common): Note front-end dependencies on layout of
+	this structure.
+
 Mon Jul 13 23:18:39 1998  Craig Burley  <burley@gnu.org>
 
 	* stmt.c (expand_expr_stmt): If not assigning fresh

gcc/tree.h

@@ -154,7 +154,11 @@ typedef union tree_node *tree;
 /* Every kind of tree node starts with this structure,
    so all nodes have these fields.
 
-   See the accessor macros, defined below, for documentation of the fields.  */
+   See the accessor macros, defined below, for documentation of the fields. 
+
+   DO NOT change the layout of tree_common unless absolutely necessary.  Some
+   front-ends (namely g++) depend on the internal layout of this tructure.
+   See my_tree_cons in the cp subdir for such uglyness.  Ugh.  */
 
 struct tree_common
 {