x/tools/internal/lsp: build errors linger after they are saved

[marwan-at-work]

As you type around with gopls turned on, errors happen because you're in the middle of typing but once the code is correct the error should disappear. This usually works well, but once you start "going to def" and go back to the original file, the behavior is no longer true. Basically, the error keeps lingering around even though the code looks ok.

I have a video to show the issue but not sure where to upload it yet since github doesn't let me. Might just put it on YouTube unless someone suggests an easier option.

[stamblerre]

I'd recommend trying out these settings in your VSCode config. It's likely that you are getting duplicate diagnostics from gopls and the Go compiler, and I wonder if they are interacting strangely.

{
    "go.buildOnSave": "off",
    "go.vetOnSave": "off"
}

/cc @ramya-rao-a

[marwan-at-work]

@stamblerre this happens before I save a file. Basically the last error just lingers around before I save the file and after as well.

PS. did turn these off since I won't need them much anymore, but the problem persists. Thanks!!

[stamblerre]

2 more instances of this error were reported here. I have also seen it myself when using gopls with VSCode-Go, but I haven't had this issue when I use an extension that only uses gopls. This will be challenging to debug, but I guess we can start by looking at the gopls logs. gopls can be started with a -logfile flag (which can be configured in VSCode setting go.languageServerFlags), so if anyone is able to reproduce this error and has a corresponding log file, that would be very helpful.

[mafredri]

If it's any help, here's a log from VSCode / gopls getting stuck on tmp not declared by package js. Can't say I did anything special. I recall typing js. and browsing the auto-complete menu on a line below where tmp was declared after that I noticed the persistent error.

gopls-stuck-tmp-not-declared.log

[ianthehat]

I see it when only using the test extension. I seems like when there are no more errors we fail to tell the client that there are no errors, so it keeps remembering whatever the last error it saw was.

[ianthehat]

Except that log clearly shows us sending the empty list back for that file.
Do we have to do something special to clear out reports from previous runs?

[stamblerre]

I'm hoping that golang.org/cl/167737 may have fixed this issue, but I'm not certain. If anyone sees this error come up again, it'd be really helpful if you could comment here (and add a log, if you have it).

[primalmotion]

To try that with vscode I can pull latest master of gopls and disable vetOnSave, buildOnSave and reenable diagnostics?

[stamblerre]

yep, that should be all you need to do.