Hi Alex,
On 1/7/21 6:04 PM, Alejandro Colomar (man-pages) wrote:
> Hi Michael,
>
> [[
> SYNOPSIS
> #include <stdlib.h>
>
> int clearenv(void);
>
> Feature Test Macro Requirements for glibc (see fea‐
> ture_test_macros(7)):
>
> clearenv():
> /* Glibc since 2.19: */ _DEFAULT_SOURCE
> || /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
>
> ]]
>
> [[
> SYNOPSIS
> #include <time.h>
>
> int dysize(int year);
>
> Feature Test Macro Requirements for glibc (see fea‐
> ture_test_macros(7)):
>
> dysize():
> Since glibc 2.19:
> _DEFAULT_SOURCE
> Glibc 2.19 and earlier:
> _BSD_SOURCE || _SVID_SOURCE
>
> ]]
>
> Which one do you prefer?
Probably the latter, since it is a little easier to read.
The former form has crept in as a result of my attempts
to keep the FTM info somewhat compact. See, for example:
chroot():
Since glibc 2.2.2:
_XOPEN_SOURCE && ! (_POSIX_C_SOURCE >= 200112L)
|| /* Since glibc 2.20: */ _DEFAULT_SOURCE
|| /* Glibc <= 2.19: */ _BSD_SOURCE
Before glibc 2.2.2:
none
waitid():
Since glibc 2.26:
_XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200809L
Glibc 2.25 and earlier:
_XOPEN_SOURCE
|| /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
|| /* Glibc <= 2.19: */ _BSD_SOURCE
The latter could be rewritten (I hope I got the expansion right)
as:
waitid():
Since glibc 2.26:
_XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200809L
Glibc 2.20 to 2.25
_XOPEN_SOURCE || _POSIX_C_SOURCE >= 200809L
Glibc 2.12 to 2.19
_XOPEN_SOURCE || _POSIX_C_SOURCE >= 200809L
|| _BSD_SOURCE
Glibc 2.11 and earlier:
_XOPEN_SOURCE || _BSD_SOURCE
That's more verbose, but perhaps also easier to read, now that
I look at it.
I'm not sure whether you are thinking of doing some global edit,
but if you are, perhaps we need to discuss this more.
Thanks,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
