We don't need to mention useIR=true in build.gradle anymore, do we?

I think we won't have to when 1.5.0 Kotlin gets released

I didn't add that flag. My kotlin is 1.4.30, and the project still works. The docs don't mention it too, but the Compose project created by Android Studio has it set.

Thanks for enlightening me too, the new IR would be enabled by default in 1.5.0 https://blog.jetbrains.com/kotlin/2021/02/the-jvm-backend-is-in-beta-let-s-make-it-stable-together/

Does this mean IR is being used by default in 1.4.30 too as well?

I think turning the compose build feature on enables IR in that module, it’s not on by default if you’re not using compose.