Better TreeTypeMaps

1. They now keep track of changed constructors in templates, updating
   the class scope as for other members.
2. Any changed members are now entered into the new class scope at exactly
   the same position as the old one. That ensures that things like caseAccessors
   still work.
3. ChangeOwners now is reflected in the prefixes of any named types.
4. Newly created classes now get their own ClassInfo type.
5. TreeTypeMaps always crete "fresh" symbols. Fresh symbols do not share
   a NamedType reference with an existing reference to some other symbol.
   This obviates b2e0e7b4, which will be reverted.

To make it work, the interface of TreeMap changed from an ownerMap function
to a substitution-like data structure working with two lists.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/core/Flags.scala b/src/dotty/tools/dotc/core/Flags.scala
index f89a5ce46..896de25fd 100644
--- a/src/dotty/tools/dotc/core/Flags.scala
+++ b/src/dotty/tools/dotc/core/Flags.scala
@@ -356,6 +356,9 @@ object Flags {
 
   // Flags following this one are not pickled
 
+  /** Symbol always defines a fresh named type */
+  final val Fresh = commonFlag(45, "<fresh>")
+
   /** Symbol is defined in a super call */
   final val InSuperCall = commonFlag(46, "<in supercall>")
 
@@ -434,7 +437,8 @@ object Flags {
   final val FromStartFlags =
     AccessFlags | Module | Package | Deferred | MethodOrHKCommon | Param | ParamAccessor | Scala2ExistentialCommon |
     InSuperCall | Touched | Static | CovariantOrOuter | ContravariantOrLabel | ExpandedName | AccessorOrSealed |
-    CaseAccessorOrTypeArgument | Frozen | Erroneous | ImplicitCommon | Permanent | SelfNameOrImplClass
+    CaseAccessorOrTypeArgument | Fresh | Frozen | Erroneous | ImplicitCommon | Permanent |
+    SelfNameOrImplClass
 
   assert(FromStartFlags.isTermFlags && FromStartFlags.isTypeFlags)
   // TODO: Should check that FromStartFlags do not change in completion