win32: ensure that localtime_r() is declared even in i686 builds

[dscho]

Git for Windows plans on reducing the scope of its i686 support after v2.55.0 even further, therefore this patch (which I had forgotten about) needs to be in that version.

cc: Patrick Steinhardt ps@pks.im

[dscho]

/submit

[gitgitgadget]

Submitted as pull.2157.git.1782117847057.gitgitgadget@gmail.com

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[gitgitgadget]

Patrick Steinhardt wrote on the Git mailing list (how to reply to this email):

On Mon, Jun 22, 2026 at 08:44:06AM +0000, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
> 
> The `__MINGW64__` constant is defined, surprise, surprise, only when
> building for a 64-bit CPU architecture.
> 
> Therefore using it as a guard to define `_POSIX_C_SOURCE` (so that
> `localtime_r()` is declared, among other functions) is not enough, we
> also need to check `__MINGW32__`.
> 
> Technically, the latter constant is defined even for 64-bit builds. But
> let's make things a bit easier to understand by testing for both
> constants.

So it would suffice to use `__MINGW32__`? In any case, I agree that
making this explicit feels sane.

> Making it so fixes this compile warning (turned error in GCC v14.1):
> 
>   archive-zip.c: In function 'dos_time':
>   archive-zip.c:612:9: error: implicit declaration of function 'localtime_r';
>   did you mean 'localtime_s'? [-Wimplicit-function-declaration]
>     612 |         localtime_r(&time, &tm);
>         |         ^~~~~~~~~~~
>         |         localtime_s

Makes sense. The function is available in C23, but we don't use it.
Otherwise, it's enabled with `_POSIX_C_SOURCE` according to [1].

> diff --git a/compat/posix.h b/compat/posix.h
> index 2f01564b0d..e2e794cad7 100644
> --- a/compat/posix.h
> +++ b/compat/posix.h
> @@ -56,7 +56,7 @@
>  # define UNUSED
>  #endif
>  
> -#ifdef __MINGW64__
> +#if defined(__MINGW32__) || defined(__MINGW64__)
>  #define _POSIX_C_SOURCE 1
>  #elif defined(__sun__)
>   /*

This looks nice and simple.

Thanks!

Patrick

[1]: https://man7.org/linux/man-pages/man3/ctime.3.html

[gitgitgadget]

User Patrick Steinhardt <ps@pks.im> has been added to the cc: list.