Scala2 / 3 handles type argument differently

[exoego]

Compiler version

3.0.1.RC-2

Minimized code

class Schema(impl: Class[_]) extends scala.annotation.StaticAnnotation

case class Foo[A](@Schema(classOf[List[A]]) foo: String)

Output

[error] 31 |    case class Foo[A](@Schema(classOf[List[A]]) foo: String)
[error]    |                                           ^
[error]    |                              Not found: type A

Expectation

It should compile, since it does on Scala 2.13.6.

[odersky]

It works for me without error.

[prolativ]

@odersky I tried it and it doesn't work for me either

[prolativ]

I tested this with the latest master

[odersky]

I had a stray A on my classpath. That's why it compiled for me.

[odersky]

So, yes, that's right now simply not supported. Here's what it says for the method that computes the context to be used for an annotation

  /** The context to be used for an annotation of `mdef`.
   *  This should be the context enclosing `mdef`, or if `mdef` defines a parameter
   *  the context enclosing the owner of `mdef`.
   *  Furthermore, we need to evaluate annotation arguments in an expression context,
   *  since classes defined in a such arguments should not be entered into the
   *  enclosing class.
   */
  def annotContext(mdef: untpd.Tree, sym: Symbol)(using Context): Context = {
    def isInner(owner: Symbol) = owner == sym || sym.is(Param) && owner == sym.owner
    val outer = ctx.outersIterator.dropWhile(c => isInner(c.owner)).next()
    outer.property(ExprOwner) match {
      case Some(exprOwner) if outer.owner.isClass => outer.exprContext(mdef, exprOwner)
      case _ => outer
    }
  }

It will take some effort to change this