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Re: [PATCH 3/4] http.c: avoid danging pointer to local variable `finished`

From
Junio C Hamano <gitster@pobox.com>
Date
May 24, 2022, 22:38 UTC
Message-ID
<xmqqczg2eeth.fsf@gitster.g>
In-Reply-To
<nycvar.QRO.7.76.6.2205242309160.352@tvgsbejvaqbjf.bet>
Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
Show 11 quoted lines
> Hi Junio,
>
> On Tue, 24 May 2022, Junio C Hamano wrote:
>
>> The "clear slot->finished", by the way, is what I think is the right
>> thing to do, especially that the objective is to squelch the false
>> positive warning from a new compiler.  If there is a way to annotate
>> the line for the compiler to tell it not to warn about it, that would
>> have been even better.
>
> We could do something like this:
Yuck.
Show 22 quoted lines
> -- snip --
> diff --git a/http.c b/http.c
> index b08795715f8a..2ac8d51d3668 100644
> --- a/http.c
> +++ b/http.c
> @@ -1365,7 +1365,14 @@ void run_active_slot(struct active_request_slot *slot)
>  	struct timeval select_timeout;
>  	int finished = 0;
>
> +#if __GNUC__ >= 12
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wdangling-pointer"
> +#endif
>  	slot->finished = &finished;
> +#if __GNUC__ >= 12
> +#pragma GCC diagnostic pop
> +#endif
>  	while (!finished) {
>  		step_active_slots();
> -- snap --
>
> That's quite ugly, though. And what's worse, it is pretty unreadable, too.
Yes, very ugly.  Would an unconditional
	slot->finished = NULL;
at the end squelch the warning?

Or there is a way to say "we make all warnings into errors with -Werror, but we do not want to turn this dangling-pointer warning to an error, because it has false positives"?

Or we could add "-Wno-dangling-pointer" globally, perhaps.
Previous: Ævar Arnfjörð BjarmasonNext: Johannes Schindelin
Message 15 of 23 in “ci: fix windows-build with GCC v12.x”
  1. 0/4 ci: fix windows-build with GCC v12.xJohannes Schindelin via GitGitGadget, May 24, 2022
  2. 1/4 compat/win32/syslog: fix use-after-reallocJohannes Schindelin via GitGitGadget, May 24, 2022
  3. Johannes SchindelinMay 24, 2022
  4. Junio C HamanoMay 24, 2022
  5. 2/4 nedmalloc: avoid new compile errorJohannes Schindelin via GitGitGadget, May 24, 2022
  6. Ævar Arnfjörð BjarmasonMay 24, 2022
  7. René ScharfeMay 24, 2022
  8. Johannes SchindelinMay 24, 2022
  9. Ævar Arnfjörð BjarmasonMay 24, 2022
  10. 3/4 http.c: avoid danging pointer to local variable `finished`Johannes Schindelin via GitGitGadget, May 24, 2022
  11. Ævar Arnfjörð BjarmasonMay 24, 2022
  12. Junio C HamanoMay 24, 2022
  13. Johannes SchindelinMay 24, 2022
  14. Ævar Arnfjörð BjarmasonMay 24, 2022
  15. Junio C HamanoMay 24, 2022
  16. Johannes SchindelinMay 25, 2022
  17. Ævar Arnfjörð BjarmasonMay 25, 2022
  18. 4/4 dir.c: avoid "exceeds maximum object size" error with GCC v12.xJohannes Schindelin via GitGitGadget, May 24, 2022
  19. Ævar Arnfjörð BjarmasonMay 24, 2022
  20. Johannes SchindelinMay 24, 2022
  21. Derrick StoleeMay 25, 2022
  22. Junio C HamanoMay 25, 2022
  23. Jeff HostetlerMay 24, 2022

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