False exhaustivity for GADT under separate compilation

[eejbyfeldt]

Compiler version

3.7.2

Minimized code

In file1.scala

sealed trait N[T]
case class MakeTuple[T <: Tuple](v: T) extends N[T]

In file2.scala

object test {
  def t[T](expr: N[T]): Any =
    expr match {
      case MakeTuple(_) => ???
    }
}

Output

$ scalac file1.scala && scalac file2.scala
-- [E029] Pattern Match Exhaustivity Warning: file2.scala:3:4 ------------------
3 |    expr match {
  |    ^^^^
  |    match may not be exhaustive.
  |
  |    It would fail on pattern case: MakeTuple(_)
  |
  | longer explanation available when compiling with `-explain`
1 warning found

But compiling in a single scalac call e.g scalac file1.scala file2.scala gives no warnings.

Expectation

Ideally no warning should be produced. But consistently producing the warning would also be an improvement.

[eejbyfeldt]

3.3.5 produces the warning even when compiled together

$ scala-cli --scala-version 3.3.5 node.scala failure.scala
Warning: setting /home/ejbyfeldt/dev/scala_playground as the project root directory for this run.
Starting compilation server
Compiling project (Scala 3.3.5, JVM (17))
[warn] ./failure.scala:3:5
[warn] match may not be exhaustive.
[warn] 
[warn] It would fail on pattern case: MakeTuple(_)
[warn]     expr match {
[warn]     ^^^^
Compiled project (Scala 3.3.5, JVM (17))
[error]  No main class found

But that could just be that version does not properly support this case.