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    SubjectRe: Patch to remove undefined C code
    On Tue, 17 Oct 2000, Bernd Schmidt wrote:

    > On Tue, 17 Oct 2000, Richard Guenther wrote:
    >
    > > On Mon, 16 Oct 2000, Bernd Schmidt wrote:
    > >
    > > > I've been playing with some gcc patches to detect code with undefined
    > > > behaviour of the i = i++ variety. The patch below fixes all places in
    > > > the kernel that I could find. Note that in some cases, it wasn't
    > > > entirely clear what the code intended, so I had to guess.
    > > >
    > > > I haven't tested this patch at all other than to make sure it compiles.
    > >
    > > The following one is wrong, tho - should be rather
    > > str[i] = dn[i]; i++;
    >
    > Nope. (Well, at least you need to add extra braces.) The comma is a
    > sequence point.

    Umm, I thought, dn[i], i++ evaluates to i and dn[i++] evaluates
    to dn[i], so it should be either i++, dn[i-1] or the one I showed
    above?

    Richard.

    > > > diff -x log.build -x .* -dru linux-2.4/drivers/isdn/sc/debug.c linux-2.4-fixed/drivers/isdn/sc/debug.c
    > > > --- linux-2.4/drivers/isdn/sc/debug.c Thu Apr 2 01:21:04 1998
    > > > +++ linux-2.4-fixed/drivers/isdn/sc/debug.c Mon Oct 16 14:53:49 2000
    > > > @@ -70,6 +70,6 @@
    > > > int i = 0;
    > > >
    > > > while(dn[i] != ',')
    > > > - str[i] = dn[i++];
    > > > + str[i] = dn[i], i++;
    > > > str[i] = 0x0;
    > > > }
    >
    >
    > Bernd
    >

    --
    Richard Guenther <richard.guenther@student.uni-tuebingen.de>
    WWW: http://www.anatom.uni-tuebingen.de/~richi/
    The GLAME Project: http://www.glame.de/

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