Odd smatch issue?

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

static long
lx_cap_update_priv(void)
{
        const int lx_cap_mapping[4] = { 0, 0, 0 };
        int i = 63;
        /* enabling the below line disables the warning */
        //int cap_set = i == 0;
        lx_cap_mapping[i];
}


/home/gk/src/smatch/smatch: a.c:8 lx_cap_update_priv() error: buffer overflow 'lx_cap_mapping' 4 <= 63

Distilled down from some real code, obviously, but it seems odd that
just *looking* at "i" means smatch can't figure out its max value?

thanks
john