Poly function argument inhibits type inference

[Adam-Vandervorst]

Compiler version

3.1.3-RC1-bin-20220218-29f9d33-NIGHTLY

Minimized code

def poly_rec[F[_], G[_], A](nt: [X] => F[X] => G[X])(xs: List[F[A]]): List[G[A]] = xs match
  case Nil => Nil
  case x::xs => nt(x) +: poly_rec(nt)(xs) // doesn't work
//  case x::xs => nt(x) +: poly_rec[F, G, A](nt)(xs) // works

def rec[F[_], G[_], A](nt: F[A] => G[A])(xs: List[F[A]]): List[G[A]] = xs match
  case Nil => Nil
  case x::xs => nt(x) +: rec(nt)(xs)

Output

  case x::xs => nt(x) +: poly_rec(nt)(xs)
                                  ^^
Found:    (nt : scala.this.PolyFunction{apply[X](x$1: F[X]): G[X]})
Required: scala.this.PolyFunction{apply[X](x$1: scala.this.Nothing): scala.this.Any}

Expectation

Work like the second function.