[Bug c/60439] No warning for case overflow in switch statement.

[chengniansun at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60439

--- Comment #3 from Chengnian Sun <chengniansun at gmail dot com> ---
(In reply to Marek Polacek from comment #2)
> Right.  So I think there's nothing much to do.  Please reopen if you
> strongly disagree.

Hi Marek, 

>From the perspective of type system, I think no warning is fine. But from the
viewpoint of practice, IMHO this should be an overlooked case, as at runtime
there is indeed overflow. 

The reason that I filed this report is not only that Clang emits a warning on
this issue (shown as below), but also that Gcc is able to handle the value
range of expressions (if I under the report PR60036 correctly).

------------------------------------------------------------------- 

$: clang-trunk -Wswitch s.c  -c
s.c:3:8: warning: overflow converting case value to switch condition type
(111111 to 7) [-Wswitch]
  case 111111: return 1; /*warning here*/
       ^
s.c:8:3: warning: switch condition has boolean value
  switch(c && d) {
  ^      ~~~~~~