Russell King wrote:
> I think you've misunderstood the patch. The problem is that:
>
> char wibble = -1;
>
> ...
>
> if (wibble == -1)
> printk("wibble is -1\n");
> else
> printk("wibble is not -1\n");
>
> will always print "wibble is not -1" on a native unsigned char machine.
> This is a bug, which occurs very often when people don't keep their wits
> about them when using "char" to represent signed numbers. Philip's patch
> solves those discovered in the kernel thus far.
>
> Unfortunately, people forget about signed-ness issues. I actually wish
> that GCC would warn more about this type of unportable code. (eg,
> detecting an assignment or test between a bare "char" type and a
> negative number).
I suggest you write to <gcc@gcc.gnu.org> describing the warning you'd
like to see implemented. Probably nobody thought of adding it until
now.
You might consider including assumptions about bare bitfields too, whose
signedness can vary between machines.
-- Jamie
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