Reorganization of template parents.

Template parents always were constructor calls before. This is not correct because in a situation like the one
elaborated in templateParents, the trait D has the class C as supertype, but it does not call its constructor (in fact, if we added a () parameter list to make it into a constructor this would be wrong because C takes parameters.

Now parents can be either types or constructor calls.

The logic in Namer and Typer that deals with parents is cleaned up. In particular, we now construct any synthetic class parent as a full type, before calling normalizeToClassRefs. This obviates the forwardRefs logic that needed to be done in a cleanup of Namers.

Also added two more checks: (1) All parents except the first one must point to traits. (2) A trait may not call a parent class constructor.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index a867253b7..225fdbcc0 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -269,6 +269,9 @@ object SymDenotations {
     /** Is this denotation a class? */
     final def isClass: Boolean = isInstanceOf[ClassDenotation]
 
+    /** Is this denotation a non-trait class? */
+    final def isRealClass(implicit ctx: Context) = isClass && !is(Trait)
+
     /** Cast to class denotation */
     final def asClass: ClassDenotation = asInstanceOf[ClassDenotation]