Generate: val -> const val about buildkonfig

[Prototik]

@yshrsmz I found this: it allows const actuals for non-const expects
JetBrains/kotlin@b4c8544

[yshrsmz]

If I remember correctly, expect/actual cannot be used with const.
It's possible to use const when BuildKonfig generates a simple object(when you don't provide target-specific config) but to keep consistency between the 2 cases, I think we should stick to the current implementation

[yshrsmz]

I'm going to close this for now.
Feel free to reopen this if you find a way.

[Prototik]

@yshrsmz you can expose expect/actual const values with using @Suppress("CONST_VAL_WITHOUT_INITIALIZER") on the expect class.
I believe it's a bug in a compiler, and with this suppress i'm using it without any problems since kotlin 1.3.

[yshrsmz]

Hi @Prototik, thanks for the great information.

Do you know any source about this?

I found this youtrack issue, but it does not clarify if this is a bug or not
https://youtrack.jetbrains.com/issue/KT-18856/Can-we-have-expectactual-consts

[Prototik]

No, I don't have any additional information about this, i discovered it by myself via looking to source code of kotlin compiler. I think this inspection just don't care about expect/actuals and should not be forced on expect declrations (due to fact expect cannot have default implementation of any sort).

I personally used it in my own BuildConfig-like plugin for a couple years already and don't encounter any issues with this suppress, and i think it's generally safe to do that (at least with opt-in behavior as I suggested in #70).

[yshrsmz]

That's great!
Let's move it forward 💪