Change doc comment explaining widening rule

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1112,8 +1112,8 @@ trait Applications extends Compatibility {
 
   /** If `tree` is a complete application of a compiler-generated `apply`
    *  or `copy` method of an enum case, widen its type to the underlying
-   *  type by means of a type ascription, unless the expected type is an
-   *  enum case itself.
+   *  type by means of a type ascription, as long as the widened type is
+   *  still compatible with the expected type.
    *  The underlying type is the intersection of all class parents of the
    *  orginal type.
    */

tests/run-macros/i8007/Test_4.scala

@@ -39,9 +39,8 @@ enum OptInv[+T] {
   println(t5) // true
   println
 
-  // Here invariant case without explicit type parameter will instantiate T to OptInv[Any]
-  val t5_2 = OptInv.Sm[Int](23) === OptInv.Sm(23)
-  println(t5) // true
+  val t5_2 = OptInv.Sm(23) === OptInv.Sm(23)
+  println(t5_2) // true
   println
 
   val t6 = Sm(Person("Test", 23)) === Sm(Person("Test", 23))