[RFC] a68: Disable building the runtime library depending on the target

[Jose E. Marchesi]

> Hi Pietro.
>
>
> On Fri, Oct 31, 2025 at 06:36:45PM -0400, Pietro Monteiro wrote:
>> On Thu, Oct 30, 2025, at 9:31 PM, Pietro Monteiro wrote:
>> > On Thu, Oct 30, 2025, at 9:25 PM, Jose E. Marchesi wrote:
>> >> Hi Pietro.
>> >>
>> >>> I followed the model of other runtime libraries and added a
>> >>> configure.tgt file that's checked by the top-level and the libga68
>> >>> configure scripts.
>> >>>
>> >>> For now enable on all targets so it's easier to test.
>> >>
>> >> The approach LGTM.
>> >>
>> >> I think it makes sense to use "yes" as the default for
>> >> LIBGA68_SUPPORTED.
>> >>
>> >> I would also add a LIBGA68_POSIXPRED_SUPPORTED, this time with "no" as
>> >> the default and enabled in gnu/linux, bsd, darwin and other systems
>> >> where we know the posix prelude can satisfy its requirements.. wdyt?
>> 
>> I still need to write a better commit message and the changelog, but
>> I was thinking of something along these lines
>> 
>
>
> I don't think just disabling libga68 without any change in the
> compiler's assumptions is a good idea. Compiler will emit calls to
> runtime functions like `_libga68_assert', etc.
>
> E.g., if we're going to disable libga68, procedures like `assert'
> should be removed from the front-end too.  And also I don't think
> providing a dummy function for these runtime functions is a good
> idea. By using these procedures, one should not end up in a surprising
> situation.
>
> Also I built current patch, and tried to compile `(skip)' program, and
> ended up with this error:
>
>   ga68: fatal error: cannot read spec file ‘libga68.spec’: No such
>   file or directory

I think libga68 is pretty much mandatory at this point.

> My suggestion is integration of your `configure.tgt' script in my
> earlier patch:
> https://inbox.sourceware.org/algol68/20251025181021.1162724-1-mnabipoor@gnu.org/
> to disable POSIX prelude on non-POSIX platforms as a first step.
>
> Then we can iterate on how to make libga68 more customizable.
>
> WDYT?
>
> (BTW I can integrate `configure.tgt' in my earlier patch if you don't
> mind).

I think the libga68/configure.tgt hack is good to enable/disable the posix
prelude in libga68.

However, disabling the POSIX prelude also requires to not make it
available in the compiler (a68_make_standard_environ) so
libga68/configure.tgt should also be suitable to be included in the
top-level configure.ac so we don't duplicate logic.

>
>
> Regards,
> Mohammad-Reza