Re: [PATCH] Fix maybe-uninitialized warnings found by gcc 9 -flto

From: René Scharfe <l.s.r@web.de>
Date: Sep 5, 2019, 19:09 UTC
Message-ID: <b4f53049-ff50-8143-1653-d321cce6421c@web.de>
In-Reply-To: <20190905175304.GA23663@sigill.intra.peff.net>

Am 05.09.19 um 19:53 schrieb Jeff King:

Show 12 quoted lines

>>> int cmd__read_cache(int argc, const char **argv)
>>> {
>>> -       int i, cnt = 1, namelen;
>>> +       int i, cnt = 1, namelen = 0;
>
> I actually saw this one the other day, because it triggered for me when
> compiling with SANITIZE=address. AFAICT it's a false positive. "name" is
> always NULL unless skip_prefix() returns true, in which case we always
> set "namelen". And we only look at "namelen" if "name" is non-NULL.
>
> This one doesn't even require LTO, because skip_prefix() is an inline
> function. I'm not sure why the compiler gets confused here.

Yes, that's curious.

> I don't mind
> initializing namelen to 0 to silence it, though (we already set name to
> NULL, so this would just match).

Pushing the strlen() call into the loop and getting rid of namelen should work as well -- and I'd be surprised if this had a measurable performance impact.

René