revert

Author: Alex1005a

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

@@ -231,10 +231,8 @@ object Inferencing {
     def apply(x: Boolean, tp: Type): Boolean = trace(i"isFullyDefined($tp, $force)", typr) {
       try {
       val tpd = tp.dealias
-      if tpd ne tp then {
-        (tpd.isInstanceOf[TypeVar] && tp.isInstanceOf[TypeVar])
-         || apply(x, tpd)
-      } else tp match
+      if tpd ne tp then apply(x, tpd)
+      else tp match
         case _: WildcardType | _: ProtoType =>
           false
         case tvar: TypeVar if !tvar.isInstantiated =>

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

@@ -4373,6 +4373,10 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
               && (pt1 ne sharpenedPt)
               && formal.typeSymbol != defn.ClassTagClass
               && !isFullyDefined(formal, ForceDegree.none)
+              && !formal.existsPart(ty => {
+                  val dty = ty.dealias
+                  (dty ne ty) && ty.isInstanceOf[TypeVar] && dty.isInstanceOf[TypeVar]
+                }, StopAt.Static, forceLazy = false)
               && doesntContainsWildcards then
               constrainResult(tree.symbol, wtp, pt1)
             val arg = inferImplicitArg(formal, tree.span.endPos)