refactors handling of parent types

At the moment parser does too much w.r.t handling of parent types.
It checks whether a parent can have value arguments or not and
more importantly, it synthesizes constructors and super calls.

This approach is fundamentally incompatible with upcoming type macros.
Take for example the following two snippets of code:

  `class C extends A(2)`
  `class D extends A(2) with B(3)`

In the first snippet, `A` might be a type macro, therefore the super call
`A.super(2)` eagerly emitted by the parser might be meaningless. In the
second snippet parser will report an error despite that `B` might be
a type macro which expands into a trait.

Unfortunately we cannot simply augment the parser with the `isTypeMacro`
check. This is because to find out whether an identifier refers to a type
macro, one needs to perform a typecheck, which the parser cannot do.

Therefore we need a deep change in how parent types and constructors
are processed by the compiler, which is implemented in this commit.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/files/neg/t2148.check b/test/files/neg/t2148.check
index 5113b48e51..27b5dce507 100644
--- a/test/files/neg/t2148.check
+++ b/test/files/neg/t2148.check
@@ -1,4 +1,4 @@
-t2148.scala:9: error: type A is not a stable prefix
+t2148.scala:9: error: A is not a legal prefix for a constructor
   val b = new A with A#A1
                        ^
 one error found