Update TASTy reader to support Scala 3.1

[bishabosha]

As well as implementing changes for TASTy in Scala 3.1.0, also implements a few fixes:

• fix reading of singleton enum values in non-static inner class
• do not force annotations unnecessarily
• add existential flag to wildcard symbols

[bishabosha]

Open question: should we support @experimental annotation checks, so that you can't depend on a definition marked @experimental unless you are in also an experimental scope?

[SethTisue]

@bishabosha I don't seem to have permission to push to your branch, but it needs

diff --git src/compiler/scala/tools/nsc/tasty/bridge/TreeOps.scala src/compiler/scala/tools/nsc/tasty/bridge/TreeOps.scala
index 5a82115d65..82d82af03a 100644
--- src/compiler/scala/tools/nsc/tasty/bridge/TreeOps.scala
+++ src/compiler/scala/tools/nsc/tasty/bridge/TreeOps.scala
@@ -12,7 +12,7 @@
 
 package scala.tools.nsc.tasty.bridge
 
-import scala.tools.nsc.tasty.{TastyUniverse, TastyModes, ForceKinds}, TastyModes._, ForceKinds._
+import scala.tools.nsc.tasty.{TastyUniverse, TastyModes}, TastyModes._
 
 import scala.tools.tasty.TastyName
 import scala.reflect.internal.Flags

to remove unused imports. You can test this locally with set every fatalWarnings := true, which we normally only have enabled in CI.

[SethTisue]

Open question: should we support @experimental annotation checks, so that you can't depend on a definition marked @experimental unless you are in also an experimental scope?

That seems desirable to me (but not a blocker for 2.13.7, of course).

[SethTisue]

otherwise LGTM, but perhaps @lrytz would like to give it a once-over

[timothyklim]

@bishabosha

fix reading of singleton enum values in non-static inner class

Can it read opaque type from a package? For example:

package a
opaque type A = Byte
object A:
  def apply(value: Byte): A = value

In Scala 2.13.6 opaque type must be inside object A otherwise compile error.

[bishabosha]

Can it read opaque type from a package? For example:

package a
opaque type A = Byte
object A:
  def apply(value: Byte): A = value

In Scala 2.13.6 opaque type must be inside object A otherwise compile error.

@timothyklim currently in 2.13, top level definitions from Scala 3 can only be used from their wrapper object, e.g. if that code was in a/A.scala then we need to import a.A$package.A

[lrytz]

LGTM too

[bishabosha]

I realised now that 7833232 is still forcing the annotation class (to get primaryConstructor), just not explicitly - it's still not causing an issue but something to note.