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Date:   Sat, 29 Jun 2019 09:49:04 +0200 (CEST)
From:   Julia Lawall <>
To:     Markus Elfring <>
cc:     Wen Yang <>,,, Yi Wang <>,
        Gilles Muller <>,
        Nicolas Palix <>,
        Michal Marek <>,
        Masahiro Yamada <>
Subject: Re: [v2] coccinelle: semantic code search for missing of_node_put

On Sat, 29 Jun 2019, Markus Elfring wrote:

> >> +if (x == NULL || ...) S
> >> +... when != e = (T)x
> >> +    when != true x == NULL
> >
> > I wonder if this code exclusion specification is really required
> > after a null pointer was checked before.
> I would like to add another view for this implementation detail.
> The when constraint can express a software desire which can be reasonable
> to some degree. You would like to be sure that a null pointer will not occur
> after a corresponding check succeeded.

He wants to be sure that the true branch through a NULL pointer check is
not taken.

> * But I feel unsure about the circumstances under which the Coccinelle software
>   can determine this aspect actually.
> * I find that it can eventually make sense only after the content of
>   the local variable (which is identified by “x”) was modified.
>   Thus I would find the exclusion of assignments more useful at this place.

I assume that it was added because it was found to be useful.  Please
actually try things out before declaring them to be useless.


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