Kotlin ad-hoc tasks should be up-to-date when script changes but inputs and outputs do not

[mkobit]

Editing a build script causes ad-hoc tasks with inputs and outputs described to be out of date because the actions change (presumably classpath?).

Expected Behavior

Ad-hoc tasks should be UP-TO-DATE when the build script changes but the inputs/outputs do not.

Current Behavior

Tasks are out of date, and build cache will not function as expected when the build script changes.

Context

Iterating on a build script causes all the tasks before to be out of date when they should be. Leads to a bunch of work that should be unnecessary.

Steps to Reproduce (for bugs)

Kotlin:

• build.gradle.kts

  tasks.register("kotlinTask") {
    inputs.property("kotlinProp", 1)
    outputs.dir(layout.buildDirectory.dir("kotlinDir"))
    doFirst("empty") {}
  }

• Run ./gradlew kotlinTask --info

• Run ./gradlew kotlinTask --info again, see it is UP-TO-DATE

• Add some other code to build script that does not modify the build script. For example, change th ebuild script to:

  tasks.register("kotlinTask") {
    inputs.property("kotlinProp", 1)
    outputs.dir(layout.buildDirectory.dir("kotlinDir"))
    doFirst("empty") {}
  }
  tasks.register("other")

• Run ./gradlew kotlinTask --info

  > Task :kotlinTask             
  Task ':kotlinTask' is not up-to-date because:                  
    Task ':kotlinTask' has additional actions that have changed

Groovy

The same execution strategy in Groovy will result in the task being UP-TO-DATE.

• build.gradle

  tasks.register('groovyTask') {
    inputs.property('groovyProp', 1)
    outputs.dir(layout.buildDirectory.dir('groovyDir'))
    doFirst('empty') {}
  }

• Run ./gradlew groovyTask --info

• Run ./gradlew groovyTask --info again, see it is UP-TO-DATE

• Add some other code to build script that does not modify the build script. For example, change th ebuild script to:

  tasks.register('groovyTask') {
    inputs.property('groovyProp', 1)
    outputs.dir(layout.buildDirectory.dir('groovyDir'))
    doFirst('empty') {}
  }
  tasks.register('other')

• Run ./gradlew groovyTask --info, see it is UP-TO-DATE

Your Environment

• gradle --version

[wolfs]

That is expected behaviour: the implementation of the task and its actions are always an input to the task.

For the Groovy version the same should happen - so the task should be out-of-date when you change the build script. I don't quite understand why it is not the case.

The implementation of the task action is bound to the action's classpath - since if the classpath changes the behaviour of the action will change. Gradle's up-to-date checks and build cache key calculation take the implementation of the task and its actions into account.

See the documentation in the build cache guide and the user guide.

[StefMa]

For the Groovy version the same should happen - so the task should be out-of-date when you change the build script. I don't quite understand why it is not the case.

Do I understand it correctly, that the issue for this issue is tracked in #7923? 🤔

[wolfs]

Yes, the actual issue is tracked in https://github.com/gradle/gradle/issues/7923. The problem is that the Groovy task is not out of date, everything is working well for Kotlin.

[mkobit]

Thanks @wolfs , the Groovy not behaving the same is what threw me. It would definitely be useful if ad-hoc tasks were able to be up to date, but I can understand why they are not. It definitely makes the runtime input registration API a bit more problematic and requires more use of buildSrc to define either custom a tasks or Action implementations to be used instead.