[Bug c/16367] New: No worning with -ansi -pedantic about passing unsigned char * to strcmp if using -O2

["sampo dot nurmentaus at movial dot fi" <gcc-bugzilla at gcc dot gnu dot org>]

gcc -v -save-temps  -ansi -pedantic  -g  -O2 -Wall -Wmissing-prototypes
-Wmissing-declarations -Werror  -MT keke.lo -MD -MP -MF  -fPIC -DPIC -c  keke.c
-o keke.o

does not issue a warning if I try to pass unsigned char * to strcmp that takes
char * If i change -O2 to -O0 the warning is shown.
-fstrict-aliasing/-fno-strict-aliasing has no effect on this. This takes place
when a call to a function returning unsigned char * from a struct member is
given as an argument to strcmp as in example below:
(no precompiler output given, since I have no idea how to
attach it in bugzilla!)

#include <string.h>

struct mopo {
    unsigned char *keke;
};

unsigned char *kake(struct mopo *m);


int main(int argc, char **argv)
{
    struct mopo m;

    m.keke=(unsigned char *)argv[0];
        
    strcmp(kake(&m),"keke");
    return 0;
}

unsigned char *kake( struct mopo *m )
{
    return m->keke;
}

thanks in advance,

Sampo Nurmentaus

-- 
           Summary: No worning with -ansi -pedantic about passing unsigned
                    char * to strcmp if using -O2
           Product: gcc
           Version: 3.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sampo dot nurmentaus at movial dot fi
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386 gnu linux
  GCC host triplet: i386 gnu linux
GCC target triplet: i386 gnu linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16367