Switching to Kotlin Multiplatform for JVM use

[takahirom]

#304

This Pull Request aims to transition our codebase from org.jetbrains.kotlin.jvm to org.jetbrains.kotlin.multiplatform with JVM configuration. The primary intention behind this shift is to establish a foundation for adaptation to other platforms in the future.

Additionally, I encountered an issue when trying to run Dokka with a single-target multiplatform project using Kotlin 1.9.0. As a workaround, I've had to comment out the Dokka-related processes for now. You can find more information about this issue here: Kotlin/dokka#3038

Please review these changes, and let me know if there are any concerns or suggestions. Thanks!

[JakeWharton]

I'm fine with this as a starting point, but I would prefer it only be done for the main artifact.

[JakeWharton]

I'll also note that the biggest inhibitor to doing this work already is needing something like https://youtrack.jetbrains.com/issue/KT-34668 or https://youtrack.jetbrains.com/issue/KT-20427. I tried migrating the project many years ago and found the duplication/indirection needed to be too much to bear.

[takahirom]

@JakeWharton
Just to confirm, when you say 'the main artifact', are you referring to the ':kotlinpoet' module? So, should I apply the Kotlin Multiplatform plugin to the ':kotlinpoet' module and leave the other modules as they are?

[takahirom]

I have applied the KMP plugin exclusively to the kotlinpoet module. Please review the changes and let me know if there are any concerns or suggestions for improvement.

[takahirom]

I don't know why, but it seems that the format has not been applied to the main branch.
I'm not sure if I should fix this or use excludeTarget("kotlinpoet/src/commonMain/kotlin/com/squareup/kotlinpoet/ClassName.kt") as a spotless setting. 👀

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':kotlinpoet:spotlessKotlinCheck'.
> The following files had format violations:
      src/commonMain/kotlin/com/squareup/kotlinpoet/ClassName.kt
          @@ -1,5 +1,5 @@
           /*
8 actionable tasks: 8 executed
          -·*·Copyright·(C)·2014·Google,·Inc.
          +·*·Copyright·(C)·2014·Square,·Inc.

[JakeWharton]

Add the exclude, please. Basically assume whatever is in the file currently is correct.

[takahirom]

Oh, sorry, I overlooked the 'targetExclude' in the kotlinpoet module. I've fixed it since the source set name changed.
665b933

[takahirom]

TypeNameTest and JavaClassWithArrayValueAnnotation are Java classes in the test. We can separate the Java test module. But it may take some maintenance costs. What do you think?

[takahirom]

I was able to run the Java-related tests. 564b448
I didn't know that we could compile Java code in jvmTest/java.

[JakeWharton]

So this all looks great, but I'm not sure we can land it without figuring out the Dokka situation because that's a bit of a blocker.

[takahirom]

I've applied the workaround for Dokka from this link: Kotlin/dokka#3122. Now, we can view the Dokka report.

[Ayfri]

Any update ?

[JakeWharton]

Note that merging this does not immediately change the supported targets. It's still JVM only.

[JakeWharton]

There's a DSL for this we can use in a follow-up

https://github.com/cashapp/molecule/blob/782985fcf92d6385d164bbed91184f99b1f9141e/molecule-runtime/build.gradle#L42-L46