After upgrading to 1.0.9 I see these errors when r...

# ksp

[Robert Jaros]

After upgrading to 1.0.9 I see these errors when runnning any gradle task in a project using my ksp plugin:

> Cannot change attributes of dependency configuration ':generatedByKspKotlinFrontendApiDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':generatedByKspKotlinFrontendImplementationDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':generatedByKspKotlinFrontendCompileOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':generatedByKspKotlinFrontendRuntimeOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':generatedByKspKotlinFrontendIntransitiveDependenciesMetadata' after it has been resolved

[Robert Jaros]

Any ideas what could be the cause?

[Robert Jaros]

I've located a source of the problem and I have no idea how does it relate to KSP at all. I have a configuration of the bootJar Spring Boot task:

getByName("bootJar", BootJar::class) {
            dependsOn("frontendArchive", "backendMainClasses")
            classpath = files(
                kotlin.targets["backend"].compilations["main"].output.allOutputs +
                        project.configurations["backendRuntimeClasspath"] +
                        (project.tasks["frontendArchive"] as Jar).archiveFile
            )
        }

[Robert Jaros]

When I change it to this form:

getByName("bootJar", BootJar::class) {
            dependsOn("frontendArchive", "backendMainClasses")
            classpath = files(
                kotlin.targets["backend"].compilations["main"].output.allOutputs,
                        project.configurations["backendRuntimeClasspath"],
                        (project.tasks["frontendArchive"] as Jar).archiveFile
            )
        }

it works the same but the problem is gone.

[Robert Jaros]

Magic ! 🙂

[Ting-Yuan Huang]

It's magic (that I don't understand) 🙂 Here are some more context: those configurations are used to specify generated sources from each ksp task, and they are added as source sets to kotlin compilation. The configuration names never leave ksp's implementation although they are observable from outside. I should have used detached configurations 🤦

[Robert Jaros]

After hours of struggling with this issue I have some additional comments.

[Robert Jaros]

1. The problem can be easily reproduced by adding this code:

afterEvaluate {
    configurations["jvmRuntimeClasspath"].files
}

at the end of https://github.com/google/ksp/blob/main/examples/multiplatform/workload/build.gradle.kts

[Robert Jaros]

After that gradle can't even load the example project with this error:

A problem occurred configuring project ':workload'.
> Failed to notify project evaluation listener.
   > Cannot change attributes of dependency configuration ':workload:generatedByKspKotlinJsApiDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspKotlinJsImplementationDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspKotlinJsCompileOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspKotlinJsRuntimeOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspKotlinJsIntransitiveDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspTestKotlinJsApiDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspTestKotlinJsImplementationDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspTestKotlinJsCompileOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspTestKotlinJsRuntimeOnlyDependenciesMetadata' after it has been resolved
   > Cannot change attributes of dependency configuration ':workload:generatedByKspTestKotlinJsIntransitiveDependenciesMetadata' after it has been resolved

[Robert Jaros]

2. This affect KSP 1.0.9 only, there is no problem with 1.0.8.

[Robert Jaros]

3. Only KMP projects are affected.

[Robert Jaros]

4. This construct configurations["jvmRuntimeClasspath"].files is a typical way to find jvm dependencies when building "fat jar". I've googled, but couldn't find another working way to do this.

[Robert Jaros]

5. The Eclipse Vert.x gradle plugin, which internally uses shadow gradle plugin ("com.github.johnrengelman.shadow") seems to be affected by this issue as well. The project doesn't work as well with this message:

Cannot change dependencies of dependency configuration ':implementation' after it has been included in dependency resolution.

[Robert Jaros]

6. I've came up with a "horrifying" workaround for custom fat jar configuration. I've added code like this to my own gradle plugin:

afterEvaluate {
                configurations.filter { it.name.startsWith("js") && it.name.endsWith("DependenciesMetadata") }
                    .forEach {
                        configurations.remove(it)
                    }
                configurations["jvmRuntimeClasspath"].files
            }

I have no idea what it breaks (probably a lot 😉), but my project seems to work fine with this.

[Robert Jaros]

7. Still no idea how to fix shadow plugin (update: managed to fix by changing gradle plugins order)

[Robert Jaros]

@Ting-Yuan Huang any comments would be appreciated 🙂

[Ting-Yuan Huang]

Thanks for the investigation and test case. I'm investigating

[Big Chungus]

Is there an issue for this I could subscribe to? For now I have things going with tweaked Robert's workaround

afterEvaluate {
  configurations.filter { it.name.startsWith("generatedByKspKotlinJs") && it.name.endsWith("DependenciesMetadata") }
    .forEach {
      configurations.remove(it)
    }
}

[Robert Jaros]

https://github.com/google/ksp/issues/1318

[Anton Lakotka [JB]]

@Robert Jaros
So issue happened because of 3 elements:
1. configuration resolution (it was implicit in your case, through plus operator. read below for the details)
2. applied Kotlin plugin, which is happening in afterEvaluate block.
3. changing attributes of a configuration that contribute to jvmRuntimeClasspath through Configuration::extendsFrom api.
When you changed in your code from:

files(
/*...*/
project.configurations["backendRuntimeClasspath"] +
(project.tasks["frontendArchive"] as Jar).archiveFile
)

to this:

files(
/*...*/
project.configurations["backendRuntimeClasspath"],
(project.tasks["frontendArchive"] as Jar).archiveFile
)

You actually told gradle to resolve this configuration lazily.
And that fixed the issue.
Why it got resolved eagerly before that change?

Because there is no operator fun FileCollection.plus(file: File) but there is operator fun Iterable<T>.plus(element: T): List<T> and Configuration implements FileCollection which also implements Iterable<File> . And iterating over Configuration or FileCollection triggers its resolution.

So general recommendation is to try to avoid configuration resolution as much as possible. For such thing you can use protection mechanism implemented by Android Gradle Plugin: DependencyResolutionChecks.kt

Nevertheless issue is still valid for Kotlin Gradle Plugin.