Look for synthetic applies also under type applications

Fixes #15567

Author: odersky

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

@@ -103,6 +103,7 @@ 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 _ => false
   }
 

tests/neg/i15567.scala

@@ -0,0 +1,9 @@
+object Test:
+  object Foo { def apply[A]: Foo.type = this }
+  Foo() // error
+
+  case class Bar() { def apply[A]: Bar = this }
+  Bar()() // error
+
+  case class Qux() { def apply[F[_]]: Qux = this }
+  Qux()() // error