re PR c++/43680 ([DR 1022] G++ is too aggressive in optimizing away bounds checking...

re PR c++/43680 ([DR 1022] G++ is too aggressive in optimizing away bounds checking with enums)

	PR c++/43680
gcc:
	* c.opt (-fstrict-enums): New.
	* doc/invoke.texi (C++ Dialect Options): Document -fstrict-enums.
gcc/cp:
	* decl.c (finish_enum): Use the TYPE_MIN_VALUE and TYPE_MAX_VALUE
	from the selected underlying type unless -fstrict-enums.  Set
	ENUM_UNDERLYING_TYPE to	have the restricted range.
	* cvt.c (type_promotes_to): Use ENUM_UNDERLYING_TYPE.
	* class.c (check_bitfield_decl): Likewise.

From-SVN: r159006