Environment:
scala-2.9.2
squeryl 0.9.5-3 or 0.9.5-2

To reproduce:

Add this test to test/schooldb/SchoolDb.scala (I added it just after VeryVeryNestedExists, which is ignored because of a similar -- possibly the same -- problem):

  test("selectFromExists"){
    val testInstance = sharedTestInstance; import testInstance._
    val qStudents = from(students) ((s) => select(s))
    val studentsWithAnAddress =
      from(qStudents)(s =>
        where(exists(from(addresses)((a) =>
          where(s.addressId === a.id) select(a))))
          select(s)
      )
    val qAStudentIfHeHasAnAddress =
      from(studentsWithAnAddress)(s =>
        where(s.name === "Xiao")
        select(s)
      )

    val res = for (s <- qAStudentIfHeHasAnAddress) yield s.name
    val expected = List("Xiao")

    assert(expected == res, "expected :\n " + expected + "\ngot : \n " + res)

    passed('selectFromExists)

  }