use wildApprox instead isGround

Author: Alex1005a

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

@@ -6967,15 +6967,11 @@ object Types extends TypeUtils {
   end NamedPartsAccumulator
 
   class isGroundAccumulator(using Context) extends TypeAccumulator[Boolean] {
-    var tparams = util.HashSet[TypeLambda](initialCapacity = 8)
     def apply(x: Boolean, tp: Type): Boolean = x && {
       tp match {
-        case tp: TypeParamRef => tparams.contains(tp.binder)
+        case _: TypeParamRef => false
         case tp: TypeVar => apply(x, tp.underlying)
         case tp: AppliedType => tp.isGround(this)
-        case tp: HKTypeLambda =>
-          tparams.add(tp)
-          apply(x, tp.resType)
         case _ => foldOver(x, tp)
       }
     }

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

@@ -4358,7 +4358,12 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
               implicitArgs(formals2, argIndex + 1, pt)
 
             val pt1 = pt.deepenProtoTrans
-            if (pt1 `ne` pt) && (pt1 ne sharpenedPt) && pt1.isGround then
+            val approxPt = withMode(Mode.TypevarsMissContext):
+              wildApprox(pt1)
+            if (pt1 `ne` pt)
+              && (pt1 ne sharpenedPt)
+              && (AvoidWildcardsMap()(approxPt) `eq` approxPt)
+              && !isFullyDefined(formal, ForceDegree.none) then
               constrainResult(tree.symbol, wtp, pt1)
             val arg = inferImplicitArg(formal, tree.span.endPos)