errnos.h usage

[Konstantin Kharlamov]

On Wed, 2024-02-14 at 04:59 +0000, Lucas Augusto Valentim Dantas via
Libc-help wrote:
> Hello, I have been playing around with Doom's source code, the 90s
> one, and I have noticed that it has a header included named errnos.h
> that I have recently learned that it was actually present in glibc
> beginning from 2.0.0 (I think) until 2.0.7. Could anyone shed light
> on why it was added to glibc and later removed?
>
> https://sources.debian.org/src/glibc/2.0.7t-1/sysdeps/unix/sysv/linux/errnos.h/
> https://github.com/id-Software/DOOM/blob/master/linuxdoom-1.10/i_video.c#L49

Judging by the commit 5107cf1d7d27f17c6de68ec15a8e8d9dd5b471c1 description from 1997:

>            * sysdeps/mach/hurd/errnos.h: -> .../bits/errno.h
>            * sysdeps/standalone/arm/errnos.h: Likewise.
>            * sysdeps/stub/errnos.h: Likewise.
>            * sysdeps/unix/bsd/bsd4.4/errnos.h: Likewise.
>            * sysdeps/unix/sysv/linux/errnos.h: Likewise.

all platform-specific `errnos.h` were merged into a single file `errno.h`.