Remove tvars cleanup in typedArgs

Author: dwijnand

compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala

@@ -500,29 +500,6 @@ object ProtoTypes {
           // We only need to propagate constraints if we typed the arguments in a different
           // TyperState and if that created additional constraints.
           if (passedTyperState ne protoTyperState) && (oldConstraint ne newConstraint) then
-            // To respect the pre-condition of `mergeConstraintWith` and keep
-            // `protoTyperState` committable we must ensure that it does not
-            // contain any type variable which don't already exist in the passed
-            // TyperState. This is achieved by instantiating any such type
-            // variable. NOTE: this does not suffice to discard type variables
-            // in ancestors of `protoTyperState`, if this situation ever
-            // comes up, an assertion in TyperState will trigger and this code
-            // will need to be generalized.
-            if protoTyperState.isCommittable then
-              val passedConstraint = passedTyperState.constraint
-              val newLambdas = newConstraint.domainLambdas.filter(tl =>
-                !passedConstraint.contains(tl) || passedConstraint.hasConflictingTypeVarsFor(tl, newConstraint))
-              val newTvars = newLambdas.flatMap(_.paramRefs).map(newConstraint.typeVarOfParam)
-
-              args1.foreach(arg => Inferencing.instantiateSelected(arg.tpe, newTvars))
-
-              // `instantiateSelected` can leave some type variables uninstantiated,
-              // so we maximize them in a second pass.
-              newTvars.foreach {
-                case tvar: TypeVar if !tvar.isInstantiated =>
-                  tvar.instantiate(fromBelow = false)
-                case _ =>
-              }
             passedTyperState.mergeConstraintWith(protoTyperState)(using passedCtx)
           end if
           args1