Fix

Author: SolalPirelli

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

@@ -118,7 +118,7 @@ object Typer {
    *  apply of a function class?
    */
   private[typer] def isSyntheticApply(tree: tpd.Tree): Boolean = tree match {
-    case tree: tpd.Select => tree.hasAttachment(InsertedApply)
+    case _: (tpd.Select | tpd.Apply) => tree.hasAttachment(InsertedApply)
     case TypeApply(fn, targs) => isSyntheticApply(fn) && targs.forall(_.isInstanceOf[tpd.InferredTypeTree])
     case _ => false
   }

tests/pos/i14907.scala

@@ -5,7 +5,7 @@ object Module {
     case 1 => Any *: Fill[0]
   }
   extension[N <: Int] (f: Fun[N])
-    def apply: Fill[N] => Any = ???
+    def apply(): Fill[N] => Any = ???
 
-  Fun[1]()(???)
+  Fun[1]()()(???)
 }