Error sometimes stick around even after a successful error-free check build completes

[RalfJung]

I suspect something went wrong when fixing #18283: sometimes I now see errors staying in the UI even when a check build finishes without any error. Just now, this occurred in the following sequence of events in the rustc repo:

• There was an error in library/core.
• I fixed that error and hit Ctrl-S, triggering the first check build.
• This build takes a while, so while it is still going, I also made some other change in compiler/rustc_passes and hit Ctrl-S again, triggering the second check build.

I suspect what happens is that the 2nd build does not mention that library/core got built (because it didn't, it got build in the first build that was canceled when I hit Ctrl-S the second time) and hence the errors there are not cleared properly.

It is worth noting that even when library/core is finished building in the first check build, the error in that crate does not disappear. Something about the logic for recognizing the crate does not seem to work properly here. If I let the build finish as usual, the error dos eventually disappear, but if that build gets interrupted then it seems the error will never be removed.

Cc @Veykril

rust-analyzer version: rust-analyzer version: 0.3.2237-standalone [/home/r/.vscode-oss/extensions/rust-lang.rust-analyzer-0.3.2237-linux-x64/server/rust-analyzer]

[ChayimFriedman2]

I think I've also experienced this. I had to restart r-a to fix it.

[Veykril]

Ah yes, I can see us cancelling the flycheck causing us to forget about what to clear while cargo won't report for the already processed crates.

[Veykril]

Note for the future should this happen again we do have a Clear flycheck diagnostics command that should forcibly clear them all.

[rszyma]

still an issue for me, on latest nightly

[RalfJung]

This works perfectly for me now, and it is absolutely amazing. :) Thanks a lot!