On 2026-01-27T22:46:23-0800, Mark Harris wrote:
> _ISOC2X_SOURCE has been recognized since glibc 2.31 (2020).[1]
> _ISOC23_SOURCE has been recognized since glibc 2.40 (2024).[2]
> 
> [1] <https://sourceware.org/git/?p=glibc.git;a=commit;h=777d75fbc07b>
> [2] <https://sourceware.org/git/?p=glibc.git;a=commit;h=42cc619dfbc4>
> 
> Signed-off-by: Mark Harris <mark.hsj@gmail.com>

Hi Mark,

Thanks!  I've applied the patch.

Have a lovely night!
Alex

> ---
>  man/man7/feature_test_macros.7 | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/man/man7/feature_test_macros.7 b/man/man7/feature_test_macros.7
> index f0d4a51f2..a0c97f2c5 100644
> --- a/man/man7/feature_test_macros.7
> +++ b/man/man7/feature_test_macros.7
> @@ -358,6 +358,24 @@ .SS Feature test macros understood by glibc
>  .I \-std=c11
>  produces the same effects as defining this macro.
>  .TP
> +.BR _ISOC23_SOURCE " (since glibc 2.40)"
> +Exposes declarations consistent with the ISO C23 standard.
> +.IP
> +Since glibc 2.31, an equivalent macro named
> +.B _ISOC2X_SOURCE
> +was recognized
> +(because the C23 standard had not then been finalized).
> +Although the use of this macro is obsolete, glibc continues
> +to recognize it for backward compatibility.
> +.IP
> +Defining
> +.B _ISOC23_SOURCE
> +also enables C11, C99, and C95 features.
> +.IP
> +Invoking the C compiler with the option
> +.I \-std=c23
> +produces the same effects as defining this macro.
> +.TP
>  .B _LARGEFILE64_SOURCE
>  Expose definitions for the alternative API specified by the
>  LFS (Large File Summit) as a "transitional extension" to the
> @@ -692,6 +710,8 @@ .SS Default definitions, implicit definitions, and combining definitions
>  .BR _ISOC99_SOURCE ,
>  .B _ISOC11_SOURCE
>  (since glibc 2.18),
> +.B _ISOC23_SOURCE
> +(since glibc 2.40),
>  .BR _POSIX_SOURCE ,
>  .BR _POSIX_C_SOURCE  ,
>  .BR _XOPEN_SOURCE ,
> @@ -876,6 +896,10 @@ .SS Program source
>      printf("_ISOC11_SOURCE defined\[rs]n");
>  #endif
>  \&
> +#ifdef _ISOC23_SOURCE
> +    printf("_ISOC23_SOURCE defined\[rs]n");
> +#endif
> +\&
>  #ifdef _XOPEN_SOURCE
>      printf("_XOPEN_SOURCE defined: %d\[rs]n", _XOPEN_SOURCE);
>  #endif
> -- 
> 2.52.0
> 

-- 
<https://www.alejandro-colomar.es>