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

From
Junio C Hamano <gitster@pobox.com>
Date
Sep 5, 2019, 19:25 UTC
Message-ID
<xmqqr24upmtm.fsf@gitster-ct.c.googlers.com>
In-Reply-To
<b4f53049-ff50-8143-1653-d321cce6421c@web.de>
René Scharfe <l.s.r@web.de> writes:
Show 23 quoted lines
> Am 05.09.19 um 19:53 schrieb Jeff King:
>>>> 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.

Yeah, we are making strlen() call on a constant "name" in a loop over argv[]. I do not think it matters in this case, either.

Previous: René ScharfeNext: René Scharfe
Message 5 of 23 in “Fix maybe-uninitialized warnings found by gcc 9 -flto”
  1. Fix maybe-uninitialized warnings found by gcc 9 -fltoStephan Beyer, Sep 5, 2019
  2. René ScharfeSep 5, 2019
  3. Jeff KingSep 5, 2019
  4. René ScharfeSep 5, 2019
  5. Junio C HamanoSep 5, 2019
  6. René ScharfeSep 5, 2019
  7. Junio C HamanoSep 5, 2019
  8. Junio C HamanoSep 5, 2019
  9. Junio C HamanoSep 5, 2019
  10. Jeff KingSep 5, 2019
  11. Junio C HamanoSep 5, 2019
  12. Jeff KingSep 5, 2019
  13. 1/6 git-am: handle missing "author" when parsing commitJeff King, Sep 5, 2019
  14. 2/6 pack-objects: use object_id in packlist_alloc()Jeff King, Sep 5, 2019
  15. 3/6 bulk-checkin: zero-initialize hashfile_checkpointJeff King, Sep 5, 2019
  16. 4/6 diff-delta: set size out-parameter to 0 for NULL deltaJeff King, Sep 5, 2019
  17. Stephan BeyerSep 5, 2019
  18. Jeff KingSep 5, 2019
  19. Stephan BeyerSep 5, 2019
  20. Jeff KingSep 6, 2019
  21. 6/6 pack-objects: drop packlist index_pos optimizationJeff King, Sep 6, 2019
  22. 5/6 test-read-cache: drop namelen variableJeff King, Sep 5, 2019
  23. 6/6 pack-objects: drop packlist index_pos optimizationJeff King, Sep 5, 2019

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