Only pretty-print variance where it would be legal in code

Author: smarter

compiler/src/dotty/tools/dotc/core/NameOps.scala

@@ -124,6 +124,11 @@ object NameOps {
       name.rewrite { case ExpandedName(_, unexp) => unexp }
     }
 
+    /** Remove the variance from the name. */
+    def invariantName: N = likeSpaced {
+      name.rewrite { case VariantName(invariant, _) => invariant }
+    }
+
     def implClassName: N = likeSpaced(name ++ tpnme.IMPL_CLASS_SUFFIX)
 
     def errorName: N = likeSpaced(name ++ nme.ERROR)

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

@@ -635,7 +635,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
     if (tree.exists(!_.isEmpty)) encl(blockText(tree)) else ""
 
   override protected def ParamRefNameString(name: Name): String =
-    name.unexpandedName.toString
+    name.unexpandedName.invariantName.toString
 
   override protected def treatAsTypeParam(sym: Symbol): Boolean = sym is TypeParam
 

tests/repl/names.check

@@ -1,5 +1,5 @@
 scala> case class Foo[M[_]](x: M[Int]) 
 defined class Foo
 scala> Foo(Option(1))
-val res0: Foo[[+A] => Option[+A]] = Foo(Some(1))
+val res0: Foo[[+A] => Option[A]] = Foo(Some(1))
 scala> :quit