test

Author: som-snytt

tests/warn/i22742.scala

@@ -0,0 +1,11 @@
+
+//> using options -Wunused:all -Yunused:fewest
+
+trait Foldable[F[_]]:
+  def foldLeft[A, B](fa: F[A], b: B)(f: (B, A) => B): B
+
+type Id[A] = A
+
+given foldableId: Foldable[Id] =
+  new Foldable[Id]:
+    def foldLeft[A, B](fa: Id[A], b: B)(f: (B, A) => B): B = b