* tree.c (tree_size): For all 'c' and 'x' nodes, look directly
at the sizes of the relevant structures, rather than relying
on TREE_CODE_LENGTH. Call lang_hooks.tree_size to get the
sizes of any such we don't know about. Use
lang_hooks.identifier_size for IDENTIFIER_NODE.
(initializer_zerop): Use CONSTRUCTOR_ELTS.
* tree.def: Update commentary. Make fourth element of
the definition for all 'c' and 'x' nodes zero.
* langhooks.h: New hook, tree_size / LANG_HOOKS_TREE_SIZE.
* langhooks-def.h: Update to match.
* langhooks.c: New default, lhd_tree_size.
ada:
* ada-tree.def: Make fourth element for GNAT_LOOP_ID zero.
* misc.c (gnat_tree_size): New function.
(LANG_HOOKS_TREE_SIZE): Override.
cp:
* cp-tree.def: Make fourth element for all 'c' and 'x' nodes zero.
* cp-lang.c (cp_tree_size): New function.
(LANG_HOOKS_TREE_SIZE): Override.