2018-09-17  Martin Jambor  <mjambor@suse.cz>

	gcc/
	* doc/invoke.texi (Warning Options): Likewise.

	gcc/c-family/
	* c.opt (Wabsolute-value): New.

	gcc/c/
	* c-parser.c: (warn_for_abs): New function.
	(c_parser_postfix_expression_after_primary): Call it.

	testsuite/
	* gcc.dg/warn-abs-1.c: New test.
	* gcc.dg/dfp/warn-abs-2.c: Likewise.

From-SVN: r264368