linux-kernel - Re: [4/5] Coccinelle: put_device: Extend when constraints for two SmPL ellipses

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Date:   Tue, 14 May 2019 08:52:54 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Markus Elfring <Markus.Elfring@....de>
cc:     Gilles Muller <Gilles.Muller@...6.fr>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Wen Yang <wen.yang99@....com.cn>, cocci@...teme.lip6.fr,
        linux-kernel@...r.kernel.org, Yi Wang <wang.yi59@....com.cn>
Subject: Re: [4/5] Coccinelle: put_device: Extend when constraints for two
 SmPL ellipses



On Tue, 14 May 2019, Markus Elfring wrote:

> >> A SmPL ellipsis was specified for a search approach so that additional
> >> source code would be tolerated between an assignment to a local variable
> >> and the corresponding null pointer check.
> >>
> >> But such code should be restricted.
> >> * The local variable must not be reassigned there.
> >> * It must also not be forwarded to an other assignment target.
> >>
> >> Take additional casts for these code exclusion specifications into account
> >> together with optional parentheses.
> >
> > NACK.
>
> Can you agree to any information which I presented in the commit message?
>
>
> > You don't need so many type metavariables.
>
> It seems that the Coccinelle software can cope also with my SmPL code addition.
> You might feel uncomfortable with the suggested changes for a while.

It's ugly.  Much more ugly than msg =

>
>
> > Type metavariables in the same ... can be the same.
>
> Such information is good to know for the proper usage of specifications
> after a SmPL ellipsis.
>
> * Can it become required to identify involved source code placeholders
>   by extra metavariables?

I don't understand the question.

> * Would you like to clarify the probability any more how often the shown
>   type casts will be identical?

No idea about this one either.

Basically, if you have T && T, the two T's have to be the same, and T is
not pure.  If you have T || T, then only one will be matched and T remains
pure.  If you have T on two separate ...s then you are in the && case.  If
you have T in two branches of a disjunction or in two whens on the same
... you are in the || case.  Just as you can use the variable e1 over and
over on the same when, you can use the same T.

julia