Spurious erased-given-is-used error

[japgolly]

Compiler version

3.0.0-RC2-bin-20210325-eeb8340-NIGHTLY

Minimized code

sealed trait X[A]
object X {
  erased given unit: X[Unit] = compiletime.erasedValue
}

def x[A](f: List[A])(using erased X[A]): Int =
  123

def y(f: List[Unit]): Int =
  x(f)

Output

[error] 12 |  x(f)
[error]    |      ^
[error]    |      getter unit is declared as erased, but is in fact used

Expectation

It should compile.

[nicolasstucki]

Minimized

import scala.language.experimental.erasedDefinitions

type X
erased def x: X = compiletime.erasedValue

def foo(using erased X): Unit = ()

def test: Unit = foo(using x)

This only affects erased given parameters with no names. The parameter is not marked as erased.

[nicolasstucki]

Workaround: name the erased parameters

- def x[A](f: List[A])(using erased X[A]): Int =
+ def x[A](f: List[A])(using erased xa: X[A]): Int =