strict equality + explicit nulls = paradox

[megri]

Compiler version

3.0.0-RC1

Compiler settings

flags: -Yexplicit-nulls + -language:strictEquality

Minimized code

def couldBeNull: String|Null = …
if couldBeNull == null then -1 else couldBeNull.length 

Output

-- Error: <redacted>/app.scala:16:7
16 |    if couldBeNull == null then -1 else couldBeNull.length
   |       ^^^^^^^^^^^^^^^^^^^
   | Values of types Null | String and Null cannot be compared with == or !=
one error found
one error found

Expectation

no error found

[megri]

Found #10850. Seems strict equality is broken for now..

[mohe2015]

Still seems to be an issue with

@main def hello(): Unit =
  val test = if (true) {
    null
  } else {
    "test"
  }
  println(test == null)
  println(null == test)

As far as I understand scala 3 now has it's own stdlib. Does that mean we can add

given canEqualNullableNull[T]: CanEqual[T | Null, Null] = CanEqual.derived
given canEqualNullNullable[T]: CanEqual[Null, T | Null] = CanEqual.derived

or similar to the scala 3 stdlib?

[noti0na1]

Still seems to be an issue with

@main def hello(): Unit =
  val test = if (true) {
    null
  } else {
    "test"
  }
  println(test == null)
  println(null == test)

Which version are you using, and what error are you getting?
The code can be compiled with explicit nulls on my side.

Oh I remember the original issue is related to strictEquality.
Since that featurn is not actively maintained, we don't have any comment for this behaviour.