From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Johannes Sixt <j6t@kdbg.org>, Carlo Arenas <carenas@gmail.com>,
Ramsay Jones <ramsay@ramsayjones.plus.com>,
Thomas Gummerer <t.gummerer@gmail.com>,
GIT Mailing-list <git@vger.kernel.org>
Subject: Re: [PATCH] range-diff: fix some 'hdr-check' and sparse warnings
Date: Tue, 16 Jul 2019 16:01:01 -0400 [thread overview]
Message-ID: <20190716200101.GA6558@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqo91t3itl.fsf@gitster-ct.c.googlers.com>
On Tue, Jul 16, 2019 at 12:01:10PM -0700, Junio C Hamano wrote:
> And that "quiet and nice" form is a moral equivalent of
>
> struct foo foo = { 0 };
>
> that has been discussed in this thread. I'd rather not to see it
> turned into distinct FOO_INIT, BAR_INIT, etc. to force the reader to
> think these structures all need their specific initialization and
> wonder what's the reason for each of them.
I'm on the fence for that style myself. But we've definitely been
trending in that direction. Look at `git grep _INIT *.h`, many of which
are clearly zero-initializers.
I do think it's nice to be able to modify the initializers later and
feel confident that you're catching all of the users. But even then:
- it's not like we get any kind of static warning for a
zero-initialized variant (be it static or with a manual {0}
initializer)
- I know I've run into problems where code assumed memset() worked,
but it didn't (I think diff_options was one such case).
So at best it's "feel more confident", not "feel confident". :)
> One universal "struct foo foo = STRUCT_ZERO_INIT;" that is applied
> to all kinds of structure I could live with (but only if we have a
> good way to squelch sparse from bitching about it). Perhaps we
> could define it as "{}" for GCC, while keeping it "{ 0 }" for
> others. As I said, { 0 } is undefensible if we insist that a null
> pointer must be spelled NULL and not 0 (as CodingGuidelines says),
> but as long as we declare that we take "{ 0 }" as a mere convention
> (like we used to use the "int foo = foo;" convention to squelch
> "uninitialized but used" warnings) that is outside the purview of
> language-lawyers, I am perfectly fine with it, and if it is hidden
> behind a macro, that would be even better ;-)
Yeah, I am OK with that. My big question is if we use "{}" for gcc (and
compatible friends), does that squelch all of the complaints from other
compilers and tools that might see the "{0}" version? In particular,
does it work for sparse?
-Peff
next prev parent reply other threads:[~2019-07-16 20:01 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-11 22:03 [PATCH] range-diff: fix some 'hdr-check' and sparse warnings Ramsay Jones
2019-07-12 5:21 ` Johannes Sixt
2019-07-12 16:44 ` Junio C Hamano
2019-07-13 10:44 ` Johannes Sixt
2019-07-13 12:18 ` Johannes Sixt
2019-07-13 12:56 ` Carlo Arenas
2019-07-13 21:29 ` Junio C Hamano
2019-07-13 22:22 ` Carlo Arenas
2019-07-14 0:51 ` Jeff King
2019-07-14 8:30 ` Johannes Sixt
2019-07-15 14:46 ` Jeff King
2019-07-15 17:30 ` Johannes Sixt
2019-07-15 18:15 ` Jeff King
2019-07-16 19:01 ` Junio C Hamano
2019-07-16 20:01 ` Jeff King [this message]
2019-07-17 18:13 ` Junio C Hamano
2019-07-17 19:21 ` Jeff King
2019-07-17 20:10 ` Junio C Hamano
2019-07-17 17:23 ` Johannes Sixt
2019-07-15 14:47 ` Johannes Schindelin
2020-10-02 17:03 ` Junio C Hamano
2020-10-04 18:35 ` Johannes Schindelin
2019-07-14 8:15 ` Johannes Sixt
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