2007-05-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
	
	PR middle-end/7651
	PR c++/11856
	PR c/12963
	PR c/23587
	PR other/29694
	* c.opt (Wtype-limits): New.
	* doc/invoke.texi (Wtype-limits): Document it.
	(Wextra): Enabled by -Wextra.
	* c-opts.c (c_common_post_options): Enabled by -Wextra.
	* c-common.c (shorten_compare): Warn with Wtype-limits.

testsuite/
	* gcc.dg/compare6.c: Replace Wall with Wtype-limits.
	* gcc.dg/Wtype-limits.c: New.
	* gcc.dg/Wtype-limits-Wextra.c: New.
	* gcc.dg/Wtype-limits-no.c: New.
	* g++.dg/warn/Wtype-limits.C: New.
	* g++.dg/warn/Wtype-limits-Wextra.C: New.
	* g++.dg/warn/Wtype-limits-no.C: New.

From-SVN: r124875