Only look for synthetic applies under TypeApply with inferred arguments

fixes lampepfl#15969

Author: KacperFKorban

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

@@ -105,7 +105,7 @@ object Typer {
    */
   private[typer] def isSyntheticApply(tree: tpd.Tree): Boolean = tree match {
     case tree: tpd.Select => tree.hasAttachment(InsertedApply)
-    case TypeApply(fn, _) => isSyntheticApply(fn)
+    case TypeApply(fn, targs) if targs.forall(_.isInstanceOf[tpd.InferredTypeTree]) => isSyntheticApply(fn)
     case _ => false
   }
 

tests/pos/i15969.scala

@@ -0,0 +1,7 @@
+object Obj {
+  def apply[L]: Unit = ???
+
+  extension (make: Unit) def apply(value: Int): String = ???
+
+  def test: String = Obj[Int](1)
+}