gcc/

gcc/
	* c-common.c (c_fully_fold_internal): Issue a warning if a binary
	operation overflows.  Likewise non-cast unary arithmetic.
	If one arm of a conditional expression is always taken,
	inhibit evaluation warnings for the other arm.  Likewise inhibit
	evaluation warnings for the second && or || operand if the first
	operand is enough to determine the result.
	* c-typeck.c (build_conditional_expr): Apply the same inhibition
	rules here.
	(build_binary_op): Prevent duplicate evaluation warnings.

gcc/testsuite/
	* gcc.dg/overflow-warn-8.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@150594 138bc75d-0d04-0410-961f-82ee72b054a4