import stuck in a loop

[NPCRUS]

Describe the bug

https://github.com/NPCRUS/reproductions/tree/bsp-import-loop

1. open project in visual studio code
2. switch to mill-bsp
3. import project
4. extends package with extra non existent trait Base - object package extends RootModule with Base
5. import again

note: auto-import setting is switched off the mill.build is compiling with error, but metals(I guess) keep trying to import again and again

error from metals log: https://github.com/NPCRUS/reproductions/blob/bsp-import-loop/error

https://github.com/user-attachments/assets/601cde38-3406-41db-bad7-61d33a37d7fa

Expected behavior

• some sort of notification of failed import
• no looping
• error diagnostics present I want to emphasize here that error is expected, what is not expected is looping and zero notifications

Operating system

macOS

Editor/Extension

VS Code

Version of Metals

1.5.2+7-0651fd6b-SNAPSHOT

Extra context or search terms

No response

[tgodzik]

Thanks for reporting! @kasiaMarek could it be connected to your recent changes?

[kasiaMarek]

could it be connected to your recent changes?

Maybe, though I don't see right away how. I'd have to dig into this.

[NPCRUS]

On a tooling spree with @jkciesluk and @AlterEgo7 we have found following:

1. as a part of import process metals send command to mill-bsp to compile mill.build file
2. compilation fails and mill-bsp kills itself
3. metals reconnect logic kicks in and restarts the mill-bsp, then to step 1

Expected result - either of two:

1. metals should track the fact the the last command was to compile mill own file and in case of compilation error do not restart mill-bsp server, instead waits for the next change in mill file and only then resarts mill-bsp
2. mill-bsp shouldn't kill itself on unsuccessful compilation and instead should keep connection alive. This I will stress out in a mill repo

Additionally we were able to make a test case that reproduce this issue in MillServerSuite, I'll make a draft PR for it asap

[NPCRUS]

looks like guys over at mill are planning to revamp bsp server, and it suppose to fix this issue as well. I'll monitor and close this issue when it's there