Fixed #264 - failure to typecheck GADTs

The previous scheme derived the right bounds, but then failed to use them
because a TypeRef already has a set info (its bounds). Changing the bounds in
the symbol by a side effect does not affect that. This is good! But it showed
that the previous scheme was too fragile because it used a sneaky side effect
when updating the symbol info which failed to propgate into the cached
info in TypeRef.

We now keep GADT computed bounds separate form the symbol info
in a map `gadt` in the current context.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/dotty/tools/dotc/core/Flags.scala b/src/dotty/tools/dotc/core/Flags.scala
index 0e86a2936..53beae838 100644
--- a/src/dotty/tools/dotc/core/Flags.scala
+++ b/src/dotty/tools/dotc/core/Flags.scala
@@ -301,9 +301,6 @@ object Flags {
   /** Method is assumed to be stable */
   final val Stable = termFlag(24, "<stable>")
 
-  /** Info can be refined during GADT pattern match */
-  final val GADTFlexType = typeFlag(24, "<gadt-flex-type>")
-
   /** A case parameter accessor */
   final val CaseAccessor = termFlag(25, "<caseaccessor>")
 
@@ -553,7 +550,7 @@ object Flags {
 
   /** A Java interface, potentially with default methods */
   final val JavaTrait = allOf(JavaDefined, Trait, NoInits)
-  
+
     /** A Java interface */
   final val JavaInterface = allOf(JavaDefined, Trait)