Drop references to replaced TypeVar in replace

Author: odersky

compiler/src/dotty/tools/dotc/core/OrderingConstraint.scala

@@ -411,7 +411,6 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
     tvars.copyToArray(entries1, nparams)
     newConstraint(boundsMap = this.boundsMap.updated(poly, entries1))
       .init(poly)
-      .adjustDeps(poly, entries1, add = true)
   }
 
   /** Split dependent parameters off the bounds for parameters in `poly`.
@@ -433,7 +432,8 @@ class OrderingConstraint(private val boundsMap: ParamBounds,
         todos.dropInPlace(1)
       i += 1
     }
-    current.checkWellFormed()
+    current.adjustDeps(poly, current.boundsMap(poly).nn, add = true)
+      .checkWellFormed()
   }
 
 // ---------- Updates ------------------------------------------------------------

compiler/src/dotty/tools/dotc/core/Substituters.scala

@@ -193,7 +193,7 @@ object Substituters:
     def apply(tp: Type): Type = substRecThis(tp, from, to, this)(using mapCtx)
   }
 
-  final class SubstParamMap(from: ParamRef, to: Type)(using Context) extends DeepTypeMap, IdempotentCaptRefMap {
+  class SubstParamMap(from: ParamRef, to: Type)(using Context) extends DeepTypeMap, IdempotentCaptRefMap {
     def apply(tp: Type): Type = substParam(tp, from, to, this)(using mapCtx)
   }