Generic method overloading via implicit class - scala

Question

When I try to create an extension for the class via implicit class and overload existing generic method, it fails with compilation error:
error: overloaded method value getAs with alternatives:
(fieldName: String)String <and>
(i: Int)String
cannot be applied to (FooField.type)
r.getAs[String](FooField)
While overloading normal (non-generic) method via implicit works fine. Tried on Scala 2.12.10. Link to scastie. What am I missing? The code:
trait Row {
// Two overloads for `getAs[T]`
def getAs[T](i: Int): T
def getAs[T](fieldName: String): T
// Two overloads for `get`
def get(i: Int): String
def get(fieldName: String): String
}
trait Field {
def columnName: String
def columnDescription: String
}
case object FooField extends Field {
def columnName: String = "Foo"
def columnDescription: String = "Foo desc"
}
object Implicits {
implicit class RowEx(val r: Row) extends AnyVal {
def getAs[T](field: Field): T = r.getAs[T](field.columnName)
def get(field: Field): String = {
println(s"RowEx.get: field")
r.get(field.columnName)
}
}
}
object Main {
import Implicits._
// Create some instance of `Row`
val r = new Row {
def getAs[T](i: Int): T = i.toString.asInstanceOf[T]
def getAs[T](fieldName: String): T = fieldName.toString.asInstanceOf[T]
def get(i: Int): String = i.toString
def get(fieldName: String): String = fieldName
}
def main(args: Array[String]): Unit = {
// Call extension method => `RowEx.get`
println(r.get(FooField))
// Call extension method => `RowEx.get`
// Won't compile with compilation error:
/*
overloaded method value getAs with alternatives:
(fieldName: String)String
(i: Int)String
cannot be applied to (FooField.type)
*/
println(r.getAs[String](FooField))
}
}
Opened a bug: https://github.com/scala/bug/issues/11810