Skip to content

Flaw in type parameter encoding? #741

Closed
@smarter

Description

@smarter

The following:

class Foo[A]

class Outer {
  class Bar[B] extends Foo[B]
}

object Test {
  def test = {
    val foo: Foo[Int] = {
      val o = new Outer
      new o.Bar[Int]
     }
  }
}

Fails with:

error: type mismatch:
 found   : Foo{A = Outer$Bar$$B; Outer$Bar$$B = Int}
 required: Foo[Int]
    val foo: Foo[Int] = {
                        ^

The issue is that in TypeAssigner#avoid we replace:

o.Bar { Outer$bar$$B = Int }

by (this is not the best solution, see #711, but that's a separate issue):

Foo { Foo$$A = Outer$bar$$B } { Outer$Bar$$B = Int }

But at this point we cannot infer that Foo$$A = Int because these refinements are not prefixed by RefinedThis so they're independent. It seems that we should either:

  • change the encoding of type parameters
  • or add a simple and robust method to go from o.Bar { Outer$Bar$$B = Int } to its "real" parent type which is Foo { Foo$$A = Int }.

@odersky : what do you think?

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions