Re: [PATCH] unpack-objects: fix compilation warning/error due to missing braces

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Jul 12, 2022, 06:28 UTC
Message-ID: <CAPig+cQMJcUc4gpRDpR=Q8M44rTjUA7SWgXNmzrnDH7V12z0dQ@mail.gmail.com>
In-Reply-To: <xmqq7d4kp8l6.fsf@gitster.g>

On Mon, Jul 11, 2022 at 12:38 AM Junio C Hamano <gitster@pobox.com> wrote:

Show 21 quoted lines

> Eric Sunshine <sunshine@sunshineco.com> writes:
> > On Sun, Jul 10, 2022 at 10:00 PM Han Xin <chiyutianyi@gmail.com> wrote:
> >> On Sun, Jul 10, 2022 at 4:12 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
> >> > [1]: `cc --version` => "Apple LLVM version 10.0.0 (clang-1000.10.44.4)"
> >> > -       git_zstream zstream = { 0 };
> >> > +       git_zstream zstream = {{ 0 }};
> >>
> >> Not a comment, just wondering, when should I use "{ { 0 } }" and when
> >> should I use "{ 0 }"?
> >
> > I don't have a good answer. More modern `clang` versions don't seem to
> > complain about plain old `{0}` here, but the older `clang` with which
> > I'm stuck does complain.
>
> I think, from the language-lawyer perspective, "{ 0 }" is how we
> should spell these initialization when we are not using designated
> initializers, even when the first member of the struct happens to be
> a struct.
>
> The older clang that complains at you is simply buggy, and I think
> we had the same issue with older sparse.

I can't tell from your response whether or not you intend to pick up this patch. I don't disagree that older clang may be considered buggy in this regard, but older clang versions still exist in the wild, and we already support them by applying `{{0}}` when appropriate:

    % git grep -n '{ *{ *0 *} *}'
    builtin/merge-file.c:31: xmparam_t xmp = {{0}};
    builtin/worktree.c:262: struct config_set cs = { { 0 } };
    oidset.h:25:#define OIDSET_INIT { { 0 } }
    worktree.c:840: struct config_set cs = { { 0 } };

so the change made by this patch is in line with existing practice on this project.