[Bug c/30020] New: missing limited range warning for a switch statement

[Bug c/30020] New: missing limited range warning for a switch statement

[sebor at roguewave dot com]

I would expect gcc to issue the same or similar warning for both functions
below but the unreachable label in the switch statement isn't flagged even
with -Wall.

In addition, a new portability warning mode/option would be useful that would
point out cases like those below irrespective of -funsigned-char or other such
options.

$ cat t.c && gcc -Wall -c -funsigned-char t.c
int foo (char c)
{
    switch (c) { case -1: return -1; };
    return 0;
}

int bar (char c)
{
    if (c == -1) return -1;
    return 0;
}
t.c: In function `bar':
t.c:9: warning: comparison is always false due to limited range of data type


-- 
           Summary: missing limited range warning for a switch statement
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sebor at roguewave dot com
 GCC build triplet: all
  GCC host triplet: all
GCC target triplet: all


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30020

[Bug c/30020] missing limited range warning for a switch statement

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-11-30 11:04 -------
I think it is harder in this case as the char is promoted to int and then we
don't demote it until after the front-end is doing its parsing ...


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
  GCC build triplet|all                         |
   GCC host triplet|all                         |
 GCC target triplet|all                         |
           Keywords|                            |diagnostic


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30020