Here's the patch I'm applying to the trunk.  The patch for 3.2.1 will be a
bit different.

2002-08-02  Jason Merrill  <jason@redhat.com>

	* langhooks-def.h (LANG_HOOKS_EXPR_SIZE): New macro.
	* langhooks.c (lhd_expr_size): Define default.
	* langhooks.h (struct lang_hooks): Add expr_size.
	* explow.c (expr_size): Call it.
	* expr.c (store_expr): Don't copy an expression of size zero.
	(expand_expr) [CONSTRUCTOR]: Use expr_size to calculate how much
	to store.
	* Makefile.in (builtins.o): Depend on langhooks.h.
cp/
	* cp-lang.c (LANG_HOOKS_EXPR_SIZE): Define.
	(cp_expr_size): New fn.
	* call.c (build_over_call): Lose empty class hackery.
	(convert_arg_to_ellipsis): Promote non-POD warning to error.
	* typeck.c (build_modify_expr): Don't use save_expr on an lvalue.