PR CI is not building rust-analyzer

[RalfJung]

In #114993 I ran down the totally wrong path for a while when I saw an RA build failure in bors -- PR CI was fine, so I was sure this must have been something odd about the bors builder. Turns out however we just don't check if RA builds, not even if src/tools/rust-analyzer is changed by the PR.

I thought the mingw-check builder does at least a check-build of everything, but that does not seem to be the case?
@rust-lang/rust-analyzer @rust-lang/infra

[lnicola]

I think this is intentional and actually saves quite a bit of CI time. Would it be better if we asked PR authors to not make unneeded changes (like compile fixes) to RA in this repo?

[RalfJung]

I think it runs ./x.py check

rust/src/ci/docker/host-x86_64/mingw-check/Dockerfile

Line 43 in 4f4dae0

python3 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \

but that doesn't include RA. It includes clippy and Miri. RA should probably be added?

[RalfJung]

A check-build of RA takes around 15s on my system. I don't think it will be prohibitively slow on CI.

[RalfJung]

For other tools like clippy and Miri, things work as follows:

• We always run a check-build on the mingw-check builder. This takes less than a minute per tool so it's fine.
• If they change, the tools builder gets enabled, and it runs their full test suite. This takes a while which is why it doesn't happen for all PRs.

At least the first bullet we should also do for RA, IMO.

[Veykril]

I agree, we should have r-a be built on rust-lang/rust CI. The main point was not running r-a's (complete) test suite I believe when people investigated CI times, which is fine.

[RalfJung]

If they change, the tools builder gets enabled, and it runs their full test suite. This takes a while which is why it doesn't happen for all PRs.

Actually, turns out since 9dfec5d we always run the tools builder.

But that's not the point here, I think this is asking for a bootstrap change: ./x.py check should also build RA. Cc @rust-lang/bootstrap

[onur-ozkan]

But that's not the point here, I think this is asking for a bootstrap change: ./x.py check should also build RA. Cc https://github.com/orgs/rust-lang/teams/bootstrap

We can add all the enabled tools from tools in the config.toml file to x check.

[onur-ozkan]

With #115111, if enabled in the configuration, rust-analyzer will be involved in the compilation.