Add Show[ParamInfo]

Requires pushing Show[Showable] down a notch

Author: dwijnand

compiler/src/dotty/tools/dotc/printing/Formatting.scala

@@ -33,9 +33,16 @@ object Formatting {
     object ShowAny extends Show[Any]:
       def show(x: Any): Shown = x
 
-    class ShowImplicits2:
+    class ShowImplicits3:
       given Show[Product] = ShowAny
 
+    class ShowImplicits2 extends ShowImplicits3:
+      given Show[ParamInfo] with
+        def show(x: ParamInfo) = x match
+          case x: Symbol      => Show[x.type].show(x)
+          case x: LambdaParam => Show[x.type].show(x)
+          case _              => ShowAny
+
     class ShowImplicits1 extends ShowImplicits2:
       given Show[ImplicitRef]      = ShowAny
       given Show[Names.Designator] = ShowAny