Follow term ref for enum values and modules

This is required to get tests/pos/i10511.scala to pass since that test
uses "enum val" knowledge transitivly.

Author: OlivierBlanvillain

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

@@ -2480,7 +2480,10 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
       sym.isAllOf(EnumCase, butNot=JavaDefined)
 
     def isEnumValueOrModule(ref: TermRef): Boolean =
-      isEnumValue(ref) || ref.termSymbol.is(Module)
+      isEnumValue(ref) || ref.termSymbol.is(Module) || (ref.info match {
+        case tp: TermRef => isEnumValueOrModule(tp)
+        case _ => false
+      })
 
     /** Can we enumerate all instantiations of this type? */
     def isClosedSum(tp: Symbol): Boolean =