Regression in type inference

[WojciechMazur]

Issues observed in multiple OpenCB projects, currently reproduced based on tkrs/fluflu
All of the projects below are pointing to the same commit when performing a project-wise bisect.

Project Name	Version	Build Logs	Notes
ichoran/kse3	0.3.11	Open CB logs	Needs minimization
appliedtopology/tda4j	0.1.0-alpha	Open CB logs	Needs minimization
thoughtworksinc/dsl.scala	2.0.0	Open CB logs	Needs minimization
sagifogel/proptics	0.5.2	Open CB logs	Needs minimization
quafadas/vecxt	0.0.25 -> 0.0.26	Open CB logs	Needs minimization
unibas-gravis/scalismo	1.0-RC1	Open CB logs	Needs minimization
tkrs/fluflu	0.24.11	Open CB logs	Reproducer below

Compiler version

3.7.0-RC1-NIGHTLY
Bisect points to #21744 - 32ac2e6

Minimized code

import java.util.concurrent.ScheduledExecutorService
import java.util.concurrent.TimeUnit

def Test = {
  val worker: ScheduledExecutorService = ???
  object Worker extends Runnable {
    def fails(): Either[Exception, Unit] = Right(worker.schedule(this, 5, TimeUnit.NANOSECONDS))
    def works(): Either[Exception, Unit] = Right {
      worker.schedule(this, 5, TimeUnit.NANOSECONDS); ()
    }
    def run(): Unit = ???
  }
}

Output

-- [E007] Type Mismatch Error: /Users/wmazur/projects/scala/community-build3/test.scala:7:65 ---------------------------------------------------------------------------------------------------------------
7 |    def fails(): Either[Exception, Unit] = Right(worker.schedule(this, 5, TimeUnit.NANOSECONDS))
  |                                                                 ^^^^
  |                                                                 Found:    (test$package.Worker : Worker.type)
  |                                                                 Required: java.util.concurrent.Callable[V]
  |
  |                                                                 where:    V is a type variable

Expectation

Should compile

[Gedochao]

cc @smarter

[smarter]

Minimized a bit more:

trait Invariant[T]

trait Foo
trait Bar[T]

trait Worker:
  def schedule(command: Foo): Invariant[?]
  def schedule[V](callable: Bar[V]): Invariant[V]

object Test:
  def test(worker: Worker, foo: Foo): Option[Unit] =
    Some(worker.schedule(foo))
    // error: Found: Foo
    //        Required: Bar[V]

[Gedochao]

@WojciechMazur we likely need to revert the change for 3.7.0