wayland-backend: Add getter for global name

[PolyMeilex]

This will be needed for events such as this one: https://wayland.app/protocols/ext-transient-seat-v1#ext_transient_seat_v1:event:ready

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 18 lines in your changes missing coverage. Please review.

Project coverage is 78.62%. Comparing base (1f6f4f5) to head (84bfcc0).
Report is 31 commits behind head on master.

Files	Patch %	Lines
wayland-backend/src/rs/server_impl/handle.rs	0.00%	15 Missing ⚠️
wayland-backend/src/server_api.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #735      +/-   ##
==========================================
+ Coverage   73.11%   78.62%   +5.51%     
==========================================
  Files          45       41       -4     
  Lines        8183     6537    -1646     
==========================================
- Hits         5983     5140     -843     
+ Misses       2200     1397     -803     

Flag	Coverage Δ
main	?
test--	80.84% <0.00%> (?)
test-client_system-	72.03% <0.00%> (?)
test-client_system-server_system	?

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[elinorbgr]

Given the CI failures, I think this bumps the minimum supported libwayland version. That is not a problem, but the CI scripts should be updated as such, and it should be documented in the changelogs.

[elinorbgr]

Ok, actually the CI no longer fixes the libwayland version, so there's nothing to update here.

But it looks like this change requires a newer version of libwayland-server than is available on the CI environment...

[PolyMeilex]

@elinorbgr I bumped Ubuntu version to 24.04, and we are green now

[ids1024]

So outside of the CI coverage tests (which were failing) this function is only needed if it's used, and won't break server_system on Ubuntu 22.04, Debian Stable, etc. that have a version of libwayland older than 1.22?

[ids1024]

No, it looks like with this anvil fails to link on 22.04 with wayland-backend/server_system but without wayland-sys/dlopen. And fails at runtime if wayland-sys/dlopen is used. Whether or not global_name is ever used.

This seems potentially problematic? I think this will break 22.04 builds of cosmic-panel (which if I recall current is using server_system, while cosmic-comp isn't).

[elinorbgr]

Could maybe this functionality be hidden behind a cargo feature?

[PolyMeilex]

How about we go libinput-rs or gtk-rs like route, and have libwayland-1.x feature for each new version from now on?

[PolyMeilex]

Any ideas how would I feature gate a function in external_library! marco?

[ids1024]

I've just done a wayland-rs release without this for now. Presumably no one needs this functionality in their compositor immediately and it can wait for the next wayland-rs release (but otherwise we can just do another release when we figure out conditional compilation here).

Using a feature naming scheme like libinput-rs or gtk-rs sounds good to me.

I guess external_library! would need to be changed to allow attributes and then include them in the output of the macro? Seems a bit annoying to deal with, but I'm not sure how else it could be done.

[PolyMeilex]

I've just done a wayland-rs release without this for now.

That's totally fine, it's more of a future proofing for people that might need ext_transient_seat_v1 in the future. I don't care if it lands today or in a year 😄

[ids1024]

Right.

Protocols like https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/40 may also want to make use of this. But it doesn't currently. (And "in a year" may be an optimistic timeline for getting things like that merged upstream...)