Use native code-coverage in GitHub

[limakzi]

GitHub provides now native code-coverage for all GitHub Code Quality organizations.
https://github.blog/changelog/2026-05-26-code-coverage-in-pull-requests-is-now-in-public-preview/

It delivers upload-code-coverage action too.

[fingolfin]

OK, interesting, thanks for the pointer.

However, using this would require changing the profiling package to produce coverage reports in the "Cobertura XML" format (whatever that is -- I didn't bother searching for it, and am not interested in learning more at this point; my point is: someone would have to invest this work before we could even think about trying this new feature out. It won't be me.)

Next, I wonder: Does this have any advantages for us over Codecov that would warrant the effort required to make it work?

There is one major disadvantage for sure: it only works on PRs originating from this repository, not on PRs authored by external contributors.

[ChrisJefferson]

I would be happy to accept a PR to add that to the profiling package if anyone was interested, probably even help, but someone would have to go learn what this thing was, and also be prepared to help debug it when it goes weird (which in my experience is common with profiling and github actions).

[limakzi]

@fingolfin Advantages:
i. Removal of dependency to external service is always good from my perspective.
ii. I think it will allow other package maintainers can use profiling without codecov and use purely our actions.

@ChrisJefferson You have my sword here.

[fingolfin]

I am not so sure i. is an advantage given how flaky GitHub is ;-). And the limitation is quite severe: GitHub's implementation provides no code coverage for outside contributions, which is where I want them the most...