32 bits compatible extensions

[mirkobrombin]

Some applications require 32 bits compatible extensions to run binaries and build 32 bits projects.

E.g. Bottles use the org.gnome.Platform.Compat.i386 extension which is not available in the elementary repository. We need that to be able to compile some libraries and run 32 bits binaries via wine.

FWIK the org.gnome.Platform.Compat.i386 is based on top of the org.freedesktop.Platform.Compat extension, including the GNOME Platform. I don't know if the best solution is to mirror it in the elementary repositories or provide a variant (maybe it's already there?)

As a workaround I am getting the necessary libraries from the AppImage but the extension might be the best solution.

I am relatively new to the world of Flatpak, let me know if I'm wrong please 😁

Originally posted by @mirkobrombin in #61

[alatiera]

👍 from me.

There are not many apps that will need a .Compat extension but it would be nice to have it. There's also a .Compat extensions for armv7 and aarch64.

[cassidyjames]

We're currently including a filtered Flathub in elementary OS to provide org.freedesktop.* extensions, so a FreeDesktop extension should be usable ootb. We could potentially add GNOME Platforms to the allowlist as well, but I'm not sure how updating that allowlist will actually work.

[gasinvein]

Reusing GNOME's 32-bit compatibility extension should be rather easy, i.e. just add org.gnome.Sdk.Compat.i386 to inherit-sdk-extensions. The problem is that this extension is valid only for x86_64 SDK, while extension-related options in flatpak-builder manifest can't be defined on per-arch basis; see flatpak/flatpak-builder#381. The KDE flatpak runtime has faced a similar problem some time ago.