Better printing of skolems

They not print similar to scalac: "?x" where `x` is a unique number.

Todo: An offline explanation what they are, similar to javac. I.e.

   ... ?3 ...

   where ?3: T

1 files changed, 7 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index b26fd6373..8eae84a51 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -2596,6 +2596,13 @@ object Types {
       if (info eq this.info) this else SkolemType(info)
     override def hashCode: Int = identityHash
     override def equals(that: Any) = this eq that.asInstanceOf[AnyRef]
+
+    private var myRepr: String = null
+    def repr(implicit ctx: Context) = {
+      if (myRepr == null) myRepr = ctx.freshName("?")
+      myRepr
+    }
+
     override def toString = s"Skolem($info)"
   }