2008-08-06  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR 8715
	* c-common.c (warn_for_sign_compare): New. Handle separately the
	case that 'constant' is zero.
	* c-typeck.c (build_binary_op): Move code to c-common.c
cp/
	* typeck.c (cp_build_binary_op): Move code to c-common.c.
testsuite/
	* gcc.dg/pr8715.c: New.
	* g++.dg/warn/pr8715.C: New.

From-SVN: r138814