count(distinct(_)) is not generated for _.distinct.size

[exlevan]

Version: 0.7.0

Steps to reproduce the behavior

Run the following code:

import io.getquill._

case class user(id: Long, name: String, age: Int)

object Main extends App {
  val db = source(new SqlMirrorSourceConfig[naming.Escape]("db"))
  val q = quote {
    query[user].map(u => u.name).distinct.size
  }
  println(db.run(q).sql)
}

Expected behavior

SELECT COUNT(DISTINCT "u"."name") FROM "user" "u"

Actual behavior

SELECT DISTINCT COUNT("u"."name") FROM "user" "u"

@getquill/maintainers

[fwbrasil]

workaround:

  import testContext._

  implicit class CountDistinct[T](q: Query[T]) {
    def countDistinct = quote(q.map(v => infix"count(distinct $v))".as[Long]))
  }
  case class User(name: String)

  val q = quote {
    query[User].map(_.name).countDistinct
  }