Exhaustive `when` mapping in Kotlin

ExhaustiveWhen.kt

@file:Suppress("PackageDirectoryMismatch") // root package looks great when importing, ie. `import exhaustive`

/**
 * Allows requiring an exhaustive mapping in a `when` block when used with the [rangeTo] operator.

 * @sample [exhaustive_when_example]
 */
@Suppress("ClassName") // lowercase because it should look like a keyword
object exhaustive {

    /** @see [exhaustive] */
    @JvmStatic @Suppress("NOTHING_TO_INLINE") // static & inline so Proguard can remove it while optimizing
    inline operator fun <T> rangeTo(whenBlock: T): T = whenBlock
}

private enum class SomeEnum { a, b, c }

private fun exhaustive_when_example(enum: SomeEnum) {
    exhaustive..when (enum) {
        SomeEnum.a -> Unit
        SomeEnum.b -> println()
        SomeEnum.c -> readLine()
    }
}

This way of doing it is much faster val <T> T.exhaustive: T get() = this

@Jswizzy: This way of doing it is much faster val <T> T.exhaustive: T get() = this

The main issue with that approach is that it pollutes the global namespace, making the extension appear on every type, which can be very confusing/misleading. In addition, the exhaustive keyword should really be placed as close as possible to the when, instead of at the end of a (potentially long) block.