Regression in katrix/perspective (non-reducible Tuple type in match types)

[jchyb]

Community build

Compiler version

3.2.2-RC2 (stopped working somewhere between 3.2.0 and 3.2.1)

Minimized code

import scala.deriving.Mirror
import scala.reflect.ClassTag

transparent inline given derived[A](
      using m: Mirror.ProductOf[A],
      idClassTag: ClassTag[Tuple.Union[m.MirroredElemTypes]]
  ): Unit = ???

case class Foo(a: Int)

val instance = derived[Foo]

Output

[error] ./test.scala:16:28: No ClassTag available for Tuple.Union[m.MirroredElemTypes]
[error] 
[error] Note: a match type could not be fully reduced:
[error] 
[error]   trying to reduce  Tuple.Union[m.MirroredElemTypes]
[error]   trying to reduce  scala.Tuple.Fold[m.MirroredElemTypes, Nothing, [x, y] =>> x | y]
[error]   failed since selector  m.MirroredElemTypes
[error]   does not match  case EmptyTuple => Nothing
[error]   and cannot be shown to be disjoint from it either.
[error]   Therefore, reduction cannot advance to the remaining case
[error] 
[error]     case h *: t => h | scala.Tuple.Fold[t, Nothing, [x, y] =>> x | y]
[error] val instance = derived[Foo]
[error]

Expectation

Should compile, like it did in 3.2.0

[prolativ]

Bisection seems to point to 8baaeae