wip/gcc10-aux promote to stable and feedback

[Fernando Oleo Blanco <irvise_ml%irvise.xyz@localhost>]

Hello everybody,

I created/modified/updated the wip/gcc10-aux package. Basically, it is
gcc10 with Ada support and I would like it to make it into stable.

The package relies explicitly on gcc6-aux to have an Ada compiler in
the system. It does not state that it uses Ada. This way, it does not
rely on the pkgsrc infra to select the correct compiler. This was done
as a recommendation in case gcc10-aux becomes the new Ada base
compiler. Its files are based on those from gcc10.

It has been tested by several people and builds correctly on x86_64
systems, both in NetBSD-current and NetBSD-9.2 [1]. Other systems have
not been tested, but they should just work. The patches that are applied
have been done in such a way that FreeBSD and DragonflyBSD also compile
(tested in gcc11 from Ravenports, which uses the same set of patches).


Current limitations, issues:
- Only works where gcc6-aux runs. So only x86* arches/systems. Ideally,
  in the future, new binary seeds would be produced for more
  arches/systems and be consumed directly.
- When using the compiler as the "main system compiler", e.g.
  PATH=/usr/pkg/gcc10-aux/bin:$PATH; packages in pkgsrc that explicitly
  depend on >=gcc10 (maybe other >=gcc* too), fail to compile. The
  reason is that the configuration step of those packages fail to work.
  Yes, you heard it right, configure says that the compiler cannot
  compile code... Which is just not true. If you copy the code snippet
  that it uses to test if the compiler can generate binaries, compile
  it manually, it just-works TM. I really do not understand what is
  happening... It makes no sense, but I cannot spend more time on it.
  You can try this by installing gcc10-aux, add it to the PATH as
  indicated and try to compile gcc10.

gcc10-aux passes all the ACATS tests on NetBSD except for 6, which
require specific OS support. This limitation is OS related and J.
Marino already sent a message to the corresponding ML [2]. It also
compiles gprbuild/xmlada/alire/gnatcoll-core v21 correctly (very
important Ada packages that hopefully will make it into pkgsrc in the
not so distant future). V22 of those packages requires gcc11.


As an extra note. I tried xcompiling gcc10 with Ada support to
NetBSD-aarch64 (RPi 3) to have another native compiler and start
generating binary seeds. This has been a glorious failure.

Upstream binutils does not support NetBSD-aarch64. I had to get the
ones from src. I can get a xcompiler, but when I use the xcompiler to
aarch64, the linker adds boggus paths that get recognised as files and
the compilation fails. I have tried some other different techniques to
no avail...

The closest I have gotten is enabling Ada in src, inside its gcc. I can
get it to build, but the build directory gets eliminated :_) (I have to
recompile everything with the clean disabled to confirm that it is
there correctly) It does not get installed since NetBSD infra does not
know anything about Ada. It should not be too difficult to get it
right, but it would require a large ammount of work and knowledge of
the build system of NetBSD, neither of which I can provide/have. I have
instructions on how to get it to compile however, if anybody wants them.

Anyhow, thanks for reading. Please, consider adding wip/gcc10-aux to
stable and any feedback is appreciated.

Regards,
Fernando Oleo Blanco

[1] https://mail-index.netbsd.org/pkgsrc-users/2021/11/04/msg034662.html
[2] https://mail-index.netbsd.org/tech-kern/2021/10/15/msg027703.html