`AbstractMethodError` when SAM-converting to trait that extends type alias of Function1

[WojciechMazur]

Based on the OpenCB failure in http4s/http4s-otel4s-middleware - build logs

Compiler version

3.8.0-RC4

Last good release: 3.8.0-RC1-bin-20250817-8c3f1a6-NIGHTLY
First bad release: 3.8.0-RC1-bin-20250818-aaa39c5-NIGHTLY
Most likely issue was present in all Scala 3 versions, activated after switching stdlib to be Scala 3 compiled

Minimized code

trait Client[F[_]]
type Middleware[F[_]] = Client[F] => Client[F]

trait ClientMiddleware[F[_]] extends Middleware[F] {
  def wrapClient(client: Client[F]): Client[F]
  final def apply(client: Client[F]): Client[F] = wrapClient(client)
  final def wrapMiddleware(that: Middleware[F]): ClientMiddleware[F] =
    (client: Client[F]) => wrapClient(that(client))
}

@main def Test = {
  trait IO[T]
  def middleware: ClientMiddleware[IO] = (client: Client[IO]) => client
  middleware.wrapMiddleware(middleware).wrapClient(new Client[IO] {})
}

Output

Exception in thread "main" java.lang.AbstractMethodError: Receiver class test$package$$$Lambda$1/0x0000007001001410 does not define or inherit an implementation of the resolved method 'abstract java.lang.Object apply(java.lang.Object)' of interface scala.Function1.
        at ClientMiddleware.wrapMiddleware$$anonfun$1(test.scala:8)
        at test$package$.Test(test.scala:14)
        at Test.main(test.scala:11)

Expectation

The missing bridge should be provided