[Bug c/29771] New: u != '\377' always true (u is unsigned char)

[r dot c dot ladan at gmail dot com]

Compiling this program using -Wall -Wcast-qual:

>>>>

#include <stdio.h>

int main(int argc, char *argv[]) {
        unsigned char u;
        u = '\377';
        printf("u=%i\n", u); /* 255, as expected */
/*      if (u != '\0')*/                /* ok */
        if (u != '\377')                /* ERROR (?) : always true due to
limited range of data type */
                printf("wow");
        return(0);
}

<<<<

gives the warning "comparison is always true due to limited range of data type"

platform is i386/Pentium 4M running FreeBSD 6.2-BETA3

Note the operator !=

Also, the complementary comparison u != '\0' does *not* give a warning
"comparison is always false due to limited data type"


-- 
           Summary: u != '\377' always true (u is unsigned char)
           Product: gcc
           Version: 3.4.6
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: r dot c dot ladan at gmail dot com
 GCC build triplet: i386-undermydesk-freebsd
  GCC host triplet: i386-undermydesk-freebsd
GCC target triplet: i386-undermydesk-freebsd


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29771