go to implementation not working for Scala 3

[tgodzik]

Describe the bug
When trying "go to implementation" in a Scala 3 code base, Metals will fail on even simple example like:

trait Foo{
  def h@@ello : String
}
class Bar extends Foo{
  def hello = ???
}

To Reproduce
Steps to reproduce the behavior:

1. Go to https://github.com/lampepfl/dotty-example-project
2. Create the above code
3. Use got to implementation on Foo.hello

Expected behavior
Metals showing Bar.hello

Installation:

• Operating system: macOS/Windows/Linux
• Editor: Visual Studio Code/Atom/Vim/Sublime/Emacs
• Metals version: v0.9.0

Additional context
Most likely an issue with semanticDB

Search terms
scala 3 go to implementation

[tgodzik]

So this is actually caused by the fact that Scala 3 does not fill in the signature information for semanticdb. We will need to fix it first there.

[tgodzik]

This issue should be solved with the release of Dotty that comes with scala/scala3#12885

[tgodzik]

Works in 3.1.x 🎉