Nested multimodule tasks are broken in Gradle 8

[dellisd]

Describe the bug
If you have a root gradle project that you run a multimodule dokka task on (e.g. dokkaHtmlMultiModule) which includes a gradle project that itself has a multimodule setup (i.e. also has a dokkaHtmlMultiModule task), the root dokkaHtmlMultiModule task will fail with an implicit dependency error.

A problem was found with the configuration of task ':dokkaHtmlMultiModule' (type 'DokkaMultiModuleTask').
  - Gradle detected a problem with the following location: '/Users/derekellis/projects/sqldelight/sqldelight-compiler/dialect/build/dokka/htmlPartial'.
    
    Reason: Task ':dokkaHtmlMultiModule' uses this output of task ':sqldelight-compiler:dokkaHtmlMultiModule' without declaring an explicit or implicit dependency. This can lead to incorrect results being produced, depending on what order the tasks are executed.
    
    Possible solutions:
      1. Declare task ':sqldelight-compiler:dokkaHtmlMultiModule' as an input of ':dokkaHtmlMultiModule'.
      2. Declare an explicit dependency on ':sqldelight-compiler:dokkaHtmlMultiModule' from ':dokkaHtmlMultiModule' using Task#dependsOn.
      3. Declare an explicit dependency on ':sqldelight-compiler:dokkaHtmlMultiModule' from ':dokkaHtmlMultiModule' using Task#mustRunAfter.
    
    Please refer to https://docs.gradle.org/8.0.2/userguide/validation_problems.html#implicit_dependency for more details about this problem.

Note: this only happens on clean builds. If the task(s) are using a cached result of a successful run of the tasks, this error won't be thrown.

Expected behaviour
It should build normally.

To Reproduce

1. Set up a multimodule gradle project with Gradle 8+
2. Add a multimodule gradle subproject to the root project
3. Try to run the root multimodule task

Installation

• Operating system: macOS
• Build tool: Gradle 8.0.2
• Dokka version: 1.8.10

[aSemy]

Related to

• Improve compatibility with the Gradle API, and follow best practices #2700
• dokka should provide gradle-idiomatic way to aggregate documentation #1752

I've re-written the Dokka Gradle Plugin to be more compatible with the Gradle API if you'd like to try it:

https://github.com/adamko-dev/dokkatoo

The plan is to merge this plugin upstream, eventually #2839

[CLOVIS-AI]

Same error for me, reproducible in GitLab CI: job | code.

Reproduced with Gradle 8.0.2, Dokka 1.7.20 and 1.8.10.

[hfhbd]

Is there any workaround available beside using dokkatoo?

[jeffdgr8]

@hfhbd you might try this workaround. Have you read this related issue and thread?

[hfhbd]

Yes, but I don't use native targets, only multiple nested JVM modules and I just switched to dokkatoo.

[CLOVIS-AI]

After migrating to Gradle 8.1.1 and Dokka 1.8.20, without using any of the mentioned workarounds, I do not have this problem anymore.

[CLOVIS-AI]

Nevermind, it seems to depend on the project. I have another project using Gradle 8.1.1 and Dokka 1.8.20, in which the workaround is still necessary.

[aajtodd]

Seeing this in AWS SDK for Kotlin when trying to upgrade to Gradle 8.2.1 and Dokka 1.8.20.

[vmishenev]

I have experienced the same issue when I call Dokka like ./gradlew dokkaHtmlMultiModule.
It runs all dokkaHtmlMultiModule tasks in subprojects, that have children. See Gradle: executing tasks by name .
So it causes an output of the dokkaHtmlPartial task to be used by two different the dokkaHtmlMultiModule tasks without declaring dependency between them.

Workaround
Run ./gradlew :dokkaHtmlMultiModule (with a colon) instead of ./gradlew dokkaHtmlMultiModule.
It will run the :dokkaHtmlMultiModule task of the only root project. See Gradle: executing tasks by fully qualified name.

Also, there is a possible workaround to disable other unnecessary dokkaHtmlMultiModule tasks or declare an explicit dependency on them.