Removed check from addConstraint

addConstraint contained a special case where a situation like

  P { ... } <: P

was short-pathed to `return true`. But the same was not done
if the constraint was added indirectly by propagation. It's not clear
whether a special treatement of this is needed for correctness. If
it is needed, then it would be needed eberywhere. So wince we do
not want to implement it everywhere wihtout proof of necessity,
it is better to fail fast and drop the special treatment entirely.

1 files changed, 1 insertions, 13 deletions

diff --git a/src/dotty/tools/dotc/core/ConstraintHandling.scala b/src/dotty/tools/dotc/core/ConstraintHandling.scala
index 530bbfce4..2e771faf2 100644
--- a/src/dotty/tools/dotc/core/ConstraintHandling.scala
+++ b/src/dotty/tools/dotc/core/ConstraintHandling.scala
@@ -245,24 +245,12 @@ trait ConstraintHandling {
         case bound: ErrorType =>
           true
         case _ =>
-          if (occursAtToplevel(param, bound)) fromBelow
-          else if (fromBelow) addLowerBound(param, bound)
+          if (fromBelow) addLowerBound(param, bound)
           else addUpperBound(param, bound)
       }
       finally addConstraintInvocations -= 1
     }
   }
-  
-  private def occursAtToplevel(param: Type, tp: Type): Boolean = tp match {
-    case tp: PolyParam => 
-      param == tp
-    case bound: TypeProxy => 
-      occursAtToplevel(param, bound.underlying)
-    case bound: AndOrType =>
-      occursAtToplevel(param, bound.tp1) || occursAtToplevel(param, bound.tp2)
-    case _ =>
-      false
-  }
    
   def checkPropagated(msg: => String)(result: Boolean): Boolean = {
     if (result && addConstraintInvocations == 0) {