Kotlin: S3923 when branches code duplication should not be an issue

Rules and Languages Report False-positive / False-negative...
1

Language

Kotlin 2.3.21

Rule

S3923 : All branches in a conditional structure should not have exactly the same implementation

Why it is a false-positive

In Kotlin, when several types in a sealed hierarchy have a common field, we can’t extract it in a single branch. It forces to duplicate the content of branches.

Kotlin should not issue an issue in this case.

Using

SonarQube Server v2026.3 (123014)

Example

sealed interface X
data object A: X
data class B(val s: String): X 
data class C(val s: String): X

fun foo(s: String) = s + "foo"

fun main() {
    val b: X = B("bar")
	when (b) {
        A -> ""
        is B -> foo(b.s)
        is C -> foo(b.s)
    }
}