tree.h (CASE_LOW_SEEN, [...]): New macros for manipulating temporary visit flags on CASE_LABEL_EXPRs.


	* tree.h (CASE_LOW_SEEN, CASE_HIGH_SEEN): New macros for manipulating
	temporary visit flags on CASE_LABEL_EXPRs.
	* c-common.c (match_case_to_enum): Add function comment.  Avoid
	O(N) loop, by looking up both CASE_LOW_SEEN and CASE_HIGH_SEEN.
	(c_do_switch_warnings):  Reorganize to record CASE_LOW_SEEN and
	CASE_HIGH_SEEN for enumerated types.  If the switch expression is
	a constant, only warn if that constant value isn't handled.

	* gcc.dg/Wswitch-enum-2.c: New test case.
	* gcc.dg/Wswitch-enum-3.c: Likewise.

From-SVN: r116481