Bug#681557: gcc-4.7: misleading warning in xserver-xorg-input-mouse (array subscript is above array bounds)

[Petr Salinger]

Package: gcc-4.7
Version: 4.7.1-2
User: debian-...@lists.debian.org
Usertags: kfreebsd
Hi,

current gcc produces (at least on kfreebsd-amd64) misleading warning 
during compilation of xserver-xorg-input-mouse.
It together with -Werror leads to #665390.

Attached please find reduced testcase, it probably produces the same 
warning also on (linux-)amd64.

gcc -Wall -O2 bsd_mouse-bounds.c -c
  bsd_mouse-bounds.c: In function 'CheckProtocol':
  bsd_mouse-bounds.c:35:30: warning: array subscript is above array bounds 
[-Warray-bounds]

Petr

extern int xf86NameCmp(const char *s1, const char *s2);
extern void *xcalloc(int, int);

typedef const char **(*BuiltinNamesProc)(void);
typedef int (*CheckProtocolProc)(const char *protocol);

typedef struct {
 BuiltinNamesProc BuiltinNames;
 CheckProtocolProc CheckProtocol;
} OSMouseInfoRec, *OSMouseInfoPtr;



static const char *internalNames[] = {
 ((void *)0)
};

static const char *miscNames[] = {
 "SysMouse",
 ((void *)0)
};

static const char **
BuiltinNames(void)
{
    return internalNames;
}


static int
CheckProtocol(const char *protocol)
{
    int i;

    for (i = 0; internalNames[i]; i++)
        if (xf86NameCmp(protocol, internalNames[i]) == 0)
            return 1;
    for (i = 0; miscNames[i]; i++)
        if (xf86NameCmp(protocol, miscNames[i]) == 0)
            return 1;
    return 0;

}
OSMouseInfoPtr
OSMouseInit(int flags)
{
    OSMouseInfoPtr p;

    p = xcalloc(sizeof(OSMouseInfoRec), 1);
    if (!p)
        return ((void *)0);
    p->BuiltinNames = BuiltinNames;
    p->CheckProtocol = CheckProtocol;

    return p;
}