Nil and LinearSeq cannot be compared

[Bersier]

Compiler version

3.5.1-RC2

Minimized code

import scala.collection.LinearSeq

def foo[T](a: LinearSeq[T]) = a match
  case Nil => -1
  case head +: tail => head

Compiler options

 -language:strictEquality
 -Yexplicit-nulls

Compiler output

Values of types object Nil and LinearSeq[T] cannot be compared with == or !=.

Expectation

No compile-error

Note: the addition of CanEqual givens between Nil.type and LinearSeq does not help.

[noti0na1]

It is weird that the error only happens if both flags are enabled.

[goshacodes]

Hello, one more example. This bug is really blocking usage of strictEquality.
Versions: 3.3.3, 3.5.0

Example

enum Foo:
  case Bar
  case Baz(x: String)


def foo(a: Foo) = a match
  case Foo.Bar => -1
  case _ => 0

Output

Values of types Playground.Foo and Playground.Foo cannot be compared with == or !=

[noti0na1]

enum Foo:
  case Bar
  case Baz(x: String)


def foo(a: Foo) = a match
  case Foo.Bar => -1
  case _ => 0

Output

Values of types Playground.Foo and Playground.Foo cannot be compared with == or !=

For this example, the error is not related to explicit nulls, and you need to add derives CanEqual to Foo.

[goshacodes]

enum Foo:
  case Bar
  case Baz(x: String)


def foo(a: Foo) = a match
  case Foo.Bar => -1
  case _ => 0

Output

Values of types Playground.Foo and Playground.Foo cannot be compared with == or !=

For this example, the error is not related to explicit nulls, and you need to add derives CanEqual to Foo.

Hmm, ok) Thank you.