g bisect start
g bisect good v2.10.2
g bisect bad v2.10.3
g bisect run scala-run-head /Users/adriaan/Desktop/Bugs/t8431.scala

504b5f3b157de639633c962ea21f7e89152da77f is the first bad commit
commit 504b5f3b157de639633c962ea21f7e89152da77f
Author: Vlad Ureche <vlad.ureche@gmail.com>
Date:   Mon Jul 8 13:32:40 2013 +0200

    SI-7638 Superaccessor lookup after specialization
    ...

# scala-run-head
#!/bin/bash
rev=$(git rev-parse HEAD)
tmpBisect="$(mktemp -d -t bisect)"
cd "$tmpBisect" && RUNNER=scalac scala-hash $rev $@ || exit 0 # ignore compiler errors, which muddy the waters further in this case
scala-hash $rev Test

import scala.{ specialized => spec }
 
trait EqProductFoo[@spec(Int) A] {
  def eqv(x0: A): Boolean = eqvEqProductFoo(x0)
  protected def eqvEqProductFoo(x0: A) = ???
}
 
trait OrderProductFoo[@spec(Int) A] extends EqProductFoo[A] {
  override def eqv(x0: A): Boolean = eqvEqProductFoo(x0)
}
 
object Bar {
   def OrderProduct2[@spec(Int) A]: EqProductFoo[A] = {
    new OrderProductFoo[A] { }
  }
  OrderProduct2[Int]
}
 
object Test extends App {
  Bar
}

import scala.{ specialized => spec }
 
trait EqProductFoo[@spec(Int) A] {
  def eqv(x0: A): Boolean = ???
}
 
trait OrderProductFoo[@spec(Int) A] extends EqProductFoo[A] {
  override def eqv(x0: A): Boolean = super.eqv(x0)
}
 
class C extends OrderProductFoo[Int]

object Test {
  def main(args: Array[String]) {
    new C
  }
}