Hi everyone! I'm working on adding <OpenRewrite> support for Kotlin 2.+. I am trying to build on top...

# gradle

[Teodora Mihaila]

Hi everyone! I'm working on adding OpenRewrite support for Kotlin 2.+. I am trying to build on top of the following PR.
When trying to build the rewrite-kotlin module I get the following error:

Caused by: java.lang.NoSuchMethodError: 'org.jetbrains.kotlin.buildtools.api.jvm.ClasspathEntrySnapshot org.jetbrains.kotlin.buildtools.api.CompilationService.calculateClasspathSnapshot(java.io.File, org.jetbrains.kotlin.buildtools.api.jvm.ClassSnapshotGranularity, boolean)'

along with the following warning:

w: ⚠️ 'org.jetbrains.kotlin:kotlin-compiler-embeddable' Artifact Present in Build Classpath
The artifact `org.jetbrains.kotlin:kotlin-compiler-embeddable` is present in the build classpath along Kotlin Gradle plugin.
This may lead to unpredictable and inconsistent behavior.

I think it's important mentioning that I get when same error even when just trying to upgrade from Kotlin 1.9.25 to 2.2.0 in the main repo without the changes from the PR.
From what I understand the cause of the error is a transitive dependency from the Kotlin Gradle plugin that introduces an older version on the build class path.
So far I have tried to fix this by doing the following:
1. Exploring the config files for any hardcoded old Kotlin version, but nothing was found.
2. Commenting out the dependencies in the build.gradle.kts file of rewrite-kotlin module to prevent transitive leaks. Nothing changed.
3. Using the following command: ./gradlew :rewrite-kotlin:dependencies | grep -A 5 "kotlin-compiler-embeddable" to check which version of kotlin-compiler-embeddable was Gradle resolving. The versions all appeared to match the set Kotlin language version.
4. Disabled classpath snapshots into gradle.properties by adding: kotlin.incremental.useClasspathSnapshot=false . Nothing changed.
5. Testing multiple Gradle/JDK combinations: Gradle versions between 8.14.3 & 9.0.0 with JDK 17, 21, 23, 24. Nothing changed.
Does anyone have any pointers on what could be going wrong and how to fix it?

[tapchicoma]

it looks like something forcing incosistent version of dependencies that KGP manages. Could you share a Gradle build scan?

[mbonnin]

./gradlew :buildEnvironment

------------------------------------------------------------
Root project 'rewrite' - Eliminate tech-debt. Automatically.
------------------------------------------------------------

classpath
+--- org.openrewrite.build.root:org.openrewrite.build.root.gradle.plugin:latest.release -> 2.3.0
|    \--- org.openrewrite:rewrite-build-gradle-plugin:2.3.0
|         +--- org.openrewrite:rewrite-gradle:8.56.1
|         |    +--- org.openrewrite:rewrite-kotlin:8.56.1
|         |    |    +--- org.jetbrains:annotations:26.0.2 -> 13.0
|         |    |    +--- org.openrewrite:rewrite-java:8.56.1 (*)
|         |    |    +--- org.jetbrains.kotlin:kotlin-compiler-embeddable:1.9.25 -> 2.2.10

The rewrite-gradle-plugin pulls its own kotlin-compiler-embeddable, which might or might not be compatible with the one from KGP

[mbonnin]

I'd recommend isolating the work of rewrite-gradle-plugin in isolated classloaders

[Teodora Mihaila]

@tapchicoma thank you! I tried to create a build scan, I am currently unable to, because I don't have a Develocity account. I will work on getting a build scan.
@mbonnin thank you for the suggestion, I will try implementing it.

[Vampire]

because I don't have a Develocity account

Isn't this about FOSS? Just create one on scans.gradle.org?

[Teodora Mihaila]

You're right, this is the build scan: https://scans.gradle.com/s/66fl7l6tzztd6

[Vampire]

You apply the org.openrewrite.build.root plugin 2.3.0 which depends on rewrite-kotlin 8.56.1 which depends on kotlin-compiler-embeddable 1.9.25 I'd say and with that the newer KGP is not happy.

[Vampire]

Regarding that warning about the embeddable compiler that is

[mbonnin]

There's actually code to make newer KGP happy here. But the net result of this code is that it makes org.openrewrite.build.root sad. Can't have them both happy at the same time 😄

[mbonnin]

Unless one (or both) of them isolates its work

[tapchicoma]

@mbonnin could you try with kotlin.compiler.runViaBuildToolsApi=true in gradle.properties?

[mbonnin]

I haven't actually been able to reproduce 1:1 OP's problem but I can try

[mbonnin]

kotlin {
  compilerVersion.set(TODO())
}

Cools stuff, looks like it uncouples KGP and kotlinc versions?

[tapchicoma]

yes

[mbonnin]

Yea, can't reproduce @Teodora Mihaila problem exactly. The PR currently assembles correctly:

$ ./gradlew rewrite-kotlin:assemble
BUILD SUCCESSFUL in 15s

Tests fails for another toolchain related reason

[mbonnin]

@Teodora Mihaila any chance you can try with kotlin.compiler.runViaBuildToolsApi=true ?

[mbonnin]

Side note but this is super cool 🤩

Or you might want to update the version of the KGP but keep an older Kotlin compiler version.

Means I can get the configuration cache, project isolation, Gradle 9 updates from KGP while still targeting 2.1 for the non-JVM consumers 👀

[tapchicoma]

note: for now it is only JVM compatible 🙂

[tapchicoma]

we are working on adding support for other platforms

[mbonnin]

Alright! I was mainly interested in non-JVM for this feature so I'll wait a bit more before changing all my projects 🙂

[Teodora Mihaila]

@mbonnin Yes, it’s passing now. Right after I sent the message, a new commit was pushed that fixes the issue by forcing all Gradle configurations to use kotlin-compiler-embeddable:2.2.0.
Thanks!

[mbonnin]

@Teodora Mihaila good if it's working 🥳It's still dangerous because org.openrewrite.build.root might rely on removed APIs.
But you can worry about that when it's an actual problem