[Bug middle-end/56210] New: invalid -Warray-bounds warning

[jim at meyering dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56210

             Bug #: 56210
           Summary: invalid -Warray-bounds warning
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jim@meyering.net


The following code evokes what looks like an invalid warning with
-Warray-bounds.
It is independent of char signedness (same with -funsigned-char or with
-fsigned-char), so should be different from bug#35903.

$ cat k.c
#include <string.h>
#include <stdio.h>

void
f (void)
{
    char *p = ";";
    while (*p) {
        static char key[] = "abc";
        if (strncmp(p, key, 3) == 0) {
            p += 3;
            printf("%s\n", p);
            return;
        }
        if ((p = strchr(p, ';')) == NULL)
            return;
        p++;
    }
}
$ gcc -save-temps -O2 -Wall -c k.c
k.c: In function 'f':
k.c:12:19: warning: array subscript is above array bounds [-Warray-bounds]
             printf("%s\n", p);
                   ^
$ gcc -v
Using built-in specs.
COLLECT_GCC=/p/bin/gcc
COLLECT_LTO_WRAPPER=/p/p/gcc-2013-01-16.09h15/libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /h/j/w/co/gcc/configure --prefix=/p/p/gcc-2013-01-16.09h15
--enable-languages='c++ go'
Thread model: posix
gcc version 4.8.0 20130116 (experimental) (GCC)


Attaching the .i file momentarily...