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From:   =?UTF-8?Q?SZEDER_G=C3=A1bor?= <szeder.dev@gmail.com>
Date:   Tue, 19 Sep 2017 15:45:23 +0200
Message-ID: <CAM0VKjmuyp0pn29s8=diCpA0FPjjFJH-LcxQmOJH6Z-7WZNurA@mail.gmail.com>
Subject: Re: [PATCH] for_each_string_list_item(): behave correctly for empty list
To:     Michael Haggerty <mhagger@alum.mit.edu>
Cc:     Stefan Beller <sbeller@google.com>,
        Junio C Hamano <gitster@pobox.com>,
        Jonathan Nieder <jrnieder@gmail.com>,
        Alex Riesen <raa.lkml@gmail.com>,
        "git@vger.kernel.org" <git@vger.kernel.org>
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On Tue, Sep 19, 2017 at 3:38 PM, SZEDER G=C3=A1bor <szeder.dev@gmail.com> w=
rote:
> A bit "futuristic" option along these lines could be something like
> this, using a scoped loop variable in the outer loop to ensure that
> it's executed at most once:
>
>   #define for_each_string_list_item(item,list) \
>       for (int f_e_s_l_i =3D 1; (list)->items && f_e_s_l_i; f_e_s_l_i =3D=
 0) \
>           for (item =3D (list)->items; item < (list)->items + (list)->nr;=
 ++item)
>
> The high number of underscores are an attempt to make reasonably sure
> that the macro's loop variable doesn't shadow any variable in its
> callers or isn't being shadowed in the loop body, which might(?)
> trigger warnings in some compilers.

Well, and a poor attempt at that, because, of course, the loop
variable would still be shadowed in nested for_each_string_list_item
loops...  And our codebase has these loops nested in
entry.c:finish_delayed_checkout().

OTOH, we don't seem to care too much about shadowed variables, since
building with -Wshadow gives 91 warnings in current master...