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kotlinlang

I was just wondering if there's currently a KEEP for adding support for non-exhaustive enums.
I recently discovered this in Rust and I think it's really useful for enum classes that aren't finished yet and more enums will follow (a good example might be error codes).
I'm imagining an annotation `@NonExhaustive` which forces you to define an `else` branch *even if you cover all enums in your when clause*.
See Rust docs: <https://doc.rust-lang.org/reference/attributes/type_system.html#the-non_exhaustive-attribute>
Here's their original RFC from 2008: <https://github.com/rust-lang/rfcs/blob/master/text/2008-non-exhaustive.md>

<https://youtrack.jetbrains.com/issue/KT-38750|https://youtrack.jetbrains.com/issue/KT-38750>

That's exactly what I was looking for. Thanks :slightly_smiling_face:

I don't see why you wouldn't want error code enums to be exhaustive

In a very large code base, it's a big / potentially infeasible burden to need to update all users of your enum when you add a new value. The protocol buffer compiler emits a dummy "do not make exhaustive switches for proto enum" value to support easy enum evolution. 