[PATCH] a68: add --enable-algol68-posix-prelude

[Mohammad-Reza Nabipoor]

Hi Jose.

On Wed, Nov 05, 2025 at 10:36:42PM +0100, Jose E. Marchesi wrote:
> 
> I thought the idea was to:
> 
> > (BTW I can integrate `configure.tgt' in my earlier patch if you don't mind).
> 
> i.e. to set the posix build flag by filtering targets/hosts in configure.tgt?
> 


Yes. I started from there. And realized that integration of `configure.tgt' works
better when one is dealing with disabling/enabling libFOO.
For that scenario, we have to have `libFOO/configure.tgt' file, and source that
file once in top-level `configure.ac' and once in `libFOO/configure.ac'.
But what we're doing here is not disabling `libga68' (as we consider it necessary
for ga68), but we want to disable a subset of `libga68' and subset of `gcc/algol68'
features (namely POSIX prelude support in the language and in the runtime).
So the check should be happen in `libga68/configure.ac' and
`gcc/algol68/configure.ac' files, and I couldn't figure out where to put
`configure.tgt' to be accessible to both `libga68' and `gcc/algol68'.

Instead I just copied the logic of `configure.tgt' after defining the
`AC_ARG_ENABLE', like this:

```
  case "${target}" in
  *-*-linux*    | *-*-gnu*     | *-*-k*bsd*-gnu | *-*-kopensolaris*-gnu | \
  *-*-netbsd*   | *-*-freebsd* | *-*-openbsd*   | *-*-dragonfly* | \
  *-*-solaris2* | *-*-hpux11*  | *-*-darwin*    | *-*-aix*)
    enable_algol68_posix_prelude=yes
    ;;
  *)
    enable_algol68_posix_prelude=no
    ;;
  esac
```

And I think a little bit of dupplication is easier than finding a place
for hiding a few lines of shell code.


Sorry for not being explicit when sending the patch!


Regards,
Mohammad-Reza