Fix #4582: use untpd.New in maybeCall

[Medowhill]

No description provided.

[dottybot]

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[allanrenucci]

This doesn't exercice the code you changed but I would add a test with an argument list. E.g.

trait T2[A: Numeric](x: Int)
class T2X[A: Numeric] extends T[A](1)

[Medowhill]

I've just added it.

[Blaisorblade]

I love when people fix bugs by removing code! ❤️

[Blaisorblade]

@Medowhill Could we also test the interaction with #4798? That is, try adding variants of those tests with context bounds. Hopefully that already just works!

[Medowhill]

I think this issue is orthogonal to #4798 because #4798 is related to type aliases for classes rather than traits. For example, the following code is already compiled successfully at the master branch.

trait A[X]
object O {
  type T[X] = A[X]
  class B[X] extends T[X]
}

class B[X] extedns T[X] is transformed into class B[X] extends Object with A[X].

However, adding a test can be meaningful. Do you think it would be better to add the following test?

trait A[X: Numeric]
object O {
  type T[X] = A[X]
  class B[X: Numeric] extends T[X]
}

[Blaisorblade]

Yep, I'm talking about adding tests — I only wondered because this code calls untpd.New, which you're changing. To test the interaction I was thinking of something like the following (which fails on master and works on your branch).

class A[X: Numeric]
type T[X, Y] = A[X]
type Foo[X, Y] = T[X, Y]
class B[X: Numeric] extends Foo[X, Int]

[Medowhill]

I found a new issue while writing tests.

trait T[X]
type Foo[X, Y] = T[X]
class D[X] extends Foo[X, Unit]

trait T[X: Numeric]
type Foo[X] = T[X]
class D[X: Numeric] extends Foo[X]

Two above examples were compiled.

trait T[X: Numeric]
type Foo[X, Y] = T[X]
class D[X: Numeric] extends Foo[X, Unit]

However, this one resulted the following crash:

Exception in thread "main" java.lang.AssertionError: assertion failed: missing parameters for trait T from ($outer: C, implicit evidence$2: scala.math.Numeric) extends Object() with T {
  private implicit val evidence$2: scala.math.Numeric
  private val $outer: C
  private <accessor> def $outer(): C = this.$outer
  final def C$D$$$outer(): C = D.this.$outer()
} should have been caught in typer
	at scala.Predef$.assert(Predef.scala:219)
	at dotty.tools.dotc.transform.Mixin.nextArgument$1(Mixin.scala:209)
	at dotty.tools.dotc.transform.Mixin.$anonfun$transformTemplate$12(Mixin.scala:235)
	at scala.collection.TraversableLike$WithFilter.$anonfun$map$2(TraversableLike.scala:739)
	at scala.collection.immutable.List.foreach(List.scala:389)
	at scala.collection.TraversableLike$WithFilter.map(TraversableLike.scala:738)
	at dotty.tools.dotc.transform.Mixin.traitInits$1(Mixin.scala:217)
	at dotty.tools.dotc.transform.Mixin.$anonfun$transformTemplate$17(Mixin.scala:263)
	at scala.collection.immutable.List.flatMap(List.scala:335)
	at dotty.tools.dotc.transform.Mixin.transformTemplate(Mixin.scala:262)
	at dotty.tools.dotc.transform.Mixin.transformTemplate(Mixin.scala:98)
	at dotty.tools.dotc.transform.MegaPhase.goTemplate(MegaPhase.scala:922)

[allanrenucci]

I found a new issue while writing tests.

Please open an issue

[Medowhill]

I've just opened it: #4837.