New constraint handling

New constraint handling scheme using constraints that distinguish more between
parameter and non-parameter bounds and which track parameter bounds separately.
This allows a co-inductive formulation of satisfiability checking without fishy
cyclicity checks. It should also scale better for long chains of dependent type
variables.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/typer/ProtoTypes.scala b/src/dotty/tools/dotc/typer/ProtoTypes.scala
index e16b83afd..521f0deaa 100644
--- a/src/dotty/tools/dotc/typer/ProtoTypes.scala
+++ b/src/dotty/tools/dotc/typer/ProtoTypes.scala
@@ -325,6 +325,7 @@ object ProtoTypes {
       else pt
     val tvars = if (owningTree.isEmpty) Nil else newTypeVars(added)
     state.constraint = state.constraint.add(added, tvars)
+    ctx.typeComparer.initialize(added)
     (added, tvars)
   }
 
@@ -376,7 +377,7 @@ object ProtoTypes {
     case tp: TypeAlias => // default case, inlined for speed
       tp.derivedTypeAlias(wildApprox(tp.alias, theMap))
     case tp @ PolyParam(poly, pnum) => // !!! todo adapt to TrackingConstraint
-      ctx.typerState.constraint.at(tp) match {
+      ctx.typerState.constraint.entry(tp) match {
         case bounds: TypeBounds => wildApprox(WildcardType(bounds))
         case NoType => WildcardType(wildApprox(poly.paramBounds(pnum)).bounds)
         case inst => wildApprox(inst)