* c-common.c (warn_format, warn_format_y2k,
	warn_format_extra_args, warn_format_nonliteral): Define.
	(check_format_info): Check warn_format_nonliteral and
	warn_format_extra_args.
	(check_format_info_main): Check warn_format_y2k.
	(set_Wformat): New function.
	* c-common.h (warn_format_y2k, warn_format_extra_args,
	warn_format_nonliteral, set_Wformat): Declare.
	* c-decl.c (warn_format): Remove definition.
	(c_decode_option): Handle -Wformat-nonliteral,
	-Wno-format-extra-args and -Wno-format-y2k, and negated versions.
	Use set_Wformat.
	* invoke.texi: Document these new options and -Wformat=2.
	* toplev.c (documented_lang_options): Add these new options.

cp:
	* decl2.c (warn_format): Remove definition.
	(lang_decode_option): Handle -Wformat-nonliteral,
	-Wno-format-extra-args and -Wno-format-y2k.  Use set_Wformat.

testsuite:
	* gcc.dg/format-no-exargs-1.c, gcc.dg/format-no-y2k-1.c,
	gcc.dg/format-nonlit-1.c, gcc.dg/format-nonlit-2.c: New tests.

From-SVN: r37933