Kotlin Data Class Wildcard
Your equals method is not transitive (e.g. Point(2, 2) == Point.Wildcard and Point.Wildcard == Point(3, 3) but Point(2, 2) != Point(3, 3). See Any.equals - stdlib - Kotlin Programming Language for more details on the requirements for equals. You might also consider using EqualsTester from guava-testlib for testing your own implementations of equals.

If you define your own method instead of defining a custom, non-transitive equals implementation than your existing solution can become much simpler:

data class Point(val line: Int, val column: Int) {
    companion object {
        val wildcard = Point(-1, -1)
    }

    infix fun matches(other: Point): Boolean {
        return this == other || other === wildcard || this === wildcard
    }
}


Notes:


Point(2, 2) matches Point(-1, -1) will return false.
Point(2, 2) matches Point.wildcard will return true.
If you want both to return true then replace the === with == in matches.
Marking matches as infix is purely optional but it seems to me like a good fit.