Improve semantic information for types compiled by dotty

[bjaglin]

trafficstars

The SymbolTable required by core for finding information that is not available in SemanticDB is injected by cli using a helper from reflect, which is currently backed by scalameta's internal semanticdb-scalac-core which was written for Scala 2 class files.

https://github.com/scalacenter/scalafix/blob/c6d741174abf76c01862a2aac1b52379b106c5d9/scalafix-core/src/main/scala/scalafix/internal/v1/InternalSemanticDoc.scala#L68-L82

https://github.com/scalacenter/scalafix/blob/c6d741174abf76c01862a2aac1b52379b106c5d9/scalafix-cli/src/main/scala/scalafix/internal/v1/Args.scala#L200-L212

https://github.com/scalacenter/scalafix/blob/c6d741174abf76c01862a2aac1b52379b106c5d9/scalafix-reflect/src/main/scala/scalafix/internal/reflect/ClasspathOps.scala#L27-L33

We need to migrate to https://github.com/scalacenter/tasty-query or equivalent to provide exhaustive information about types compiled by dotty. While doing that, we should drop the need to using Scalameta internal structures as a contract between core & cli.

[tgodzik]

An alternative is to use info method that we added to the presentation compiler. It provides a similar interface as semanticdb.

[bjaglin]

Interesting! Do you know what's the PC overhead? In terms of start up time (I guess in Metals it's warm no it does not matter much) and RAM footprint?

[tgodzik]

The overhead shouldn't be too big, but it's hard to say. It's basically the addition of the compiler, which would already be added when I manage to finish the inferred type PR.