2006-12-22  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR middle-end/7651
	* c.opt (Wclobbered): New.
	* doc/invoke.texi (Wclobbered): Document it.
	(Wextra): Enabled by -Wextra.
	* c-opts.c (c_common_post_options): Enabled by -Wextra.
	* flow.c (rest_of_handle_life): Replace Wextra with Wclobbered.
	* function.c (setjmp_vars_warning): Only warn for Wclobbered.
	(setjmp_args_warning): Likewise.

testsuite/

	* gcc.dg/attr-returns_twice-1.c: Replace Wextra with Wclobbered.
	* gcc.dg/setjmp-1.c: Add explicit Wclobbered.

From-SVN: r120151