[Bug c/27126] New: -Wswitch-enums doesn't detect impossible cases in switch()

[Bug c/27126] New: -Wswitch-enums doesn't detect impossible cases in switch()

[ramune+gcc at net-ronin dot org]

Given:

int main(void)
{
enum foo { A, B, C, D} bar;
        bar = D;
        if(bar == A) {
                ;
        } else if(bar == B) {
                ;
        } else {
                switch(bar) {
                        case C:
                        case D:
                        ;
                }
        }
        return 0;
}

barbeque/zarathustra:src: /usr/local/bin/gcc-4.1.0 -Wswitch-enum a.c
a.c: In function 'main':
a.c:10: warning: enumeration value 'A' not handled in switch
a.c:10: warning: enumeration value 'B' not handled in switch

A & B aren't valid targets for the switch statement by the time it's hit as
they have been handled by the if statements above.

Locally built gcc:

barbeque/zarathustra:src: /usr/local/bin/gcc-4.1.0 -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.1.0/configure --prefix=/usr/local/stow/gcc-4.1.0
--enable-languages=c,c++,objc --infodir=/usr/local/stow/gcc-4.1.0/share/info
--mandir=/usr/local/stow/gcc-4.1.0/share/man --enable-shared --enable-threads
--enable-tls --program-suffix=-4.1.0 --enable-__cxa_atexit
--enable-version-specific-runtime-libs
--enable-targets=x86_64-unknown-linux-gnu --enable-bootstrap=lean
--disable-biarch --disable-multilib
Thread model: posix
gcc version 4.1.0

On Debian/stable from amd64.debian.net.

Also happens on gcc 3.3.5 from the Debian apt archives.


-- 
           Summary: -Wswitch-enums doesn't detect impossible cases in
                    switch()
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ramune+gcc at net-ronin dot org
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27126

[Bug c/27126] -Wswitch-enums doesn't detect impossible cases in switch()

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2006-04-12 10:17 -------
Confirmed.  But this is unlikely to be fixed as it would require moving the
diagnostic to the middle-end where this information is available.  And
diagosticts from the middle-end are notoriously frowned upon.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
  GCC build triplet|x86_64-unknown-linux-gnu    |
   GCC host triplet|x86_64-unknown-linux-gnu    |
 GCC target triplet|x86_64-unknown-linux-gnu    |
           Keywords|                            |diagnostic
           Priority|P3                          |P5
   Last reconfirmed|0000-00-00 00:00:00         |2006-04-12 10:17:19
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27126

[Bug c/27126] -Wswitch-enums doesn't detect impossible cases in switch()

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-04-13 01:27 -------


*** This bug has been marked as a duplicate of 23577 ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27126