bug#54864: GNU Cuirass reports arm64 as armhf

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

Mathieu Othacehe <othacehe@gnu.org> skribis:

>> I've had this experience before, it's very confusing (it goes on trying
>> to build a toolchain for something that is sure to fail).  Perhaps we
>> could at least have a place to refer to in the manual for the common GNU
>> triplets which make the most sense in for GNU Guix (e.g., the currently
>> supported GNU system triplets).  Currently I grep the manual for
>> disparate examples when my memory fail me.
>
> Yes, I also cannot remember those triplets even though I'm
> cross-compiling all day long.

This bug report was about system types, not triplets, but the problem is
kinda similar and equally in need of a fix.  :-)

> Maybe we could:
>
> * Define all the supported architectures in (gnu platforms). We already
>   have ARM and Hurd defined there.
>
> * Define %supported-systems and %supported-targets lists constructed by
>   parsing the <platform> records.
>
> * Use those lists to check the values passed to --system and --target
>   arguments.
>
> * Add --list-available-systems and --list-available-targets arguments
>   for all the commands supporting --system and --target arguments.
>
> WDYT?

I think it’s “nice” for ‘--target’ to accept a free-form triplet,
because users might want to target a system triplet that Guix
maintainers do not care about (we only cross-build for a handful of
triplets right now).

Based on that, I thought we could emit warnings when ‘cross-gcc’ &
co. were passed a string that doesn’t look like a valid triplet.  But
then I realized that internally these procedures are passed things that
are not quite triplets: see avr.scm and embedded.scm.

So, a list of “supported” triplets like you suggest may be a good idea,
though IMO it should be used to emit a warning rather than error out.

For system types, we can probably error out to strings not in the list.

Thoughts?

Ludo’.