Go to definition does not work or is slow

[odersky]

Since upgrading to Metals 1.5.1, the cmd-hover functionality does not work anymore or is VERY slow. Something like 5-10 seconds to go from a use to a definition 5 lines prior. About half of the times I never get an underline, the other half it takes 5-10 seconds. If I choose "go to definition" in the menu it seems to work in most or all cases (unlike cmd-hover), but it also takes 5-10 seconds. Needless to say, that makes Metals pretty annoying for development.

Expected behaviour:

Operating system:
Mac OS X

Java version:
17.0.13

Editor/extension:
Visual Studio Code v1.97.0

Metals version:
1.5.1

Extra context or search terms:

Workspace information:

• Scala versions: 3.6.4-RC1; 2.12.20; 2.13.16
• Build tools: 0. sbt
• Build servers:
  0. sbt v1.10.5
• All build tools in workspace: Bloop; sbt

[tgodzik]

Thanks for reporting, this might have something to do with the changed priority. We would use semanticdb first previously, but we switched to using the compiler itself to make sure we get a more correct result. @kasiaMarek could that be it?

Maybe we should do a race instead? 🤔

[tgodzik]

Does this happen in any particular file?

[odersky]

It seems to happen in all files of the current Scala 3 compiler. Let me try to checkout main. to see whether it's in only my branch.

[tgodzik]

Might be already fixed but for main branch and not on the RC scala/scala3#22491 and in particular #7105

[tgodzik]

You could revert to 1.5.0 for now until we are on 3.7.0 RCs

[tgodzik]

Alternatively, we can make the behaviour different on versions prior to 3.7.0.

[odersky]

It looks like it is the same for main branch for me. The fact that it takes so long if the presentation compiler is used rather than semanticDb seems to indicate some wrong usage of the presentation compiler. I mean, the compiler can compile the source file about 10 times from scratch until a find definition finds the symbol. So something's definitely amiss here.

[kasiaMarek]

We would use semanticdb first previously, but we switched to using the compiler itself to make sure we get a more correct result. @kasiaMarek could that be it?

Yeah, sounds like it...

Might be already fixed but for main branch and not on the RC scala/scala3#22491 and in particular #7105

That should make it much faster but it's only for symbols defined within the same file. If that issue affects also other go to definition requests we need to rethink the strategy here.

The fact that it takes so long if the presentation compiler is used rather than semanticDb seems to indicate some wrong usage of the presentation compiler.

That is the #7105 fix. We searched way too much for the definition.

[odersky]

I just verified it's the same for 1.5.0. It's really slow for files that are currently open. It's a bit faster for definitions that get accessed through Tasty, it seems. And it seems to affect all files in the Scala 3 project (which is about 100K lines total).

That is the #7105 fix. We searched way too much for the definition.

Good that this was fixed! In general I am all for using the PC more.

[tgodzik]

Ach right, we did two release quickly, so you would need to go back to 1.4.2

[odersky]

Yes, 1.4.2 works. I am staying on that one for now.