patchwin32: ensure that `localtime_r()` is declared even in i686 builds

2 messages between Jun 22, 2026 and Jun 22, 2026, from Johannes Schindelin via GitGitGadget, Patrick Steinhardt.

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Johannes Schindelin via GitGitGadgetJun 22, 2026, 08:44 UTC on lore

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.

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

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
    win32: ensure that localtime_r() is declared even in i686 builds
    
    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.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2157%2Fdscho%2FFix-i686-build-with-GCC-v14-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2157/dscho/Fix-i686-build-with-GCC-v14-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2157

 compat/posix.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Show changes to compat/posix.h +1 −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__)
  /*

base-commit: 8d96f09e9245ddf80c1981476fcbac8c4bb4125f

-- 
gitgitgadget

Patrick SteinhardtJun 22, 2026, 09:11 UTC in reply to Johannes Schindelin via GitGitGadget on lore

Re: [PATCH] win32: ensure that `localtime_r()` is declared even in i686 builds

On Mon, Jun 22, 2026 at 08:44:06AM +0000, Johannes Schindelin via GitGitGadget wrote:

Show 12 quoted lines

> 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.

Show 8 quoted lines

> 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].

Show 13 quoted lines

> 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