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:warning:  *Does Kotlin (WASM/JS) have a value class equality problem?*

For an App with a financial component, I'm creating a `Decimal` abstraction over:
• *JVM/Android* (`BigDecimal`) :white_check_mark: 
• *iOS* (`NSDecimalNumber`) :white_check_mark: 
• ...and finally *WasmJs* (npm's `decimal.js`) :warning: 
In such situations, for the sake of resource efficiency, we would like to use a `value class` to unify these.
This is _almost_ working fine - perfectly with *JVM/iOS* - but theres a problem with *equality* when it comes to the *wasmJs* target.

Unless I'm mistaken, it works like this: `value class` equality defers to the `equals(other: Any?)` of the wrapped value.
...which for *JVM* and *iOS*, is already mapped (as a matter of built-in KMP Interop.) to the canonical function of each platform; being JVM <https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#equals-java.lang.Object-|equals> and iOS <https://developer.apple.com/documentation/objectivec/nsobjectprotocol/isequal(_:)|isEqual>.

With *wasmJs* (and JS in general I guess?) there _is no_ canonical equality function, which entails that *common code* `equals` *can currently only ever compare object identity for WASM/JS value classes* :question: 

Current 'KMP + value class' design leaves us with no opportunity to defer to a suitable equivalence function (like the `equals` function <https://mikemcl.github.io/decimal.js/#eq|provided by decimal.js>).
This breaks use cases for naturally equatable objects.

This means the `value class` efficiency dream is off the table :interrobang: Since we can't currently intercept `equals` by either:
• Overriding `equals` in a `value class` (compiler error) :no_good: 
• Nor at the level of declaring an `external class` for JS mapping (an affordance here could be nice) :no_good: (`JsAny` vs `Any` issue)
Are there any workarounds?  While this may not be a _bug_ in KMP JS/WASM target; it appears to be a significant '_feature usability issue_' for such cases.

Hey Chris, do you know about / have you tried the compiler flag `-XXLanguage:+CustomEqualsInValueClasses`

Seems like it should resolve your compiler error, but I’m unsure if it’ll unlock your use case

Ooh, a Kotlin magic spell! Always a fun day when one of those is required.  _Sounds_ like it should do it :smile: Thank you!

Don’t forget to do a little dance while saying the magic incantation, or it may not work

Here's the YouTrack for those following along at the back: <https://youtrack.jetbrains.com/issue/KT-24874/Support-custom-equals-and-hashCode-for-value-classes|KT-24874> (Looks like I commented on it 6 years ago too lol)

:sparkles: :star:  _*It worked*_ :star: :sparkles: - Equality unit tests green across all platforms :white_check_mark:

Thank you <@U3VCTDR6E>!!!

(And whomever at *[JB]* is on top of the <https://youtrack.jetbrains.com/issue/KT-24874/Support-custom-equals-and-hashCode-for-value-classes|KT-24874> vs. WasmJs code)