doFirst and doLast in statically compiled languages gets only Task, not actual task type

[Vampire]

With Gradle 6.5.1, I tried this:

fun deleteExternalsFile(task: PackageJsonDukatTask, file: String) {
    task
            .outputs
            .files
            .asFileTree
            .matching { include("**/$file") }
            .forEach { it.delete() }
}

tasks.withType(PackageJsonDukatTask::class) {
    doLast {
        addJsModuleAnnotation("core.module_@actions_core.kt", "@actions/core")
        addJsModuleAnnotation("io.module_@actions_io.kt", "@actions/io")
        deleteExternalsFile(this, "domain.domain.module_node.kt")
    }
}

This did not compile, as this is only of type Task in doLast.
Of course I can either use this@withType or make the method parameter Task in this case as I only use Task properties,
but that's not the point.
doLast closure should know the type of the task it is called for.

[eskatos]

This is the function signatures in Task:

interface Task {
    Task doFirst(Action<? super Task> action);
    Task doLast(Action<? super Task> action);
}

A plugin implemented in Java would have the same problem

project.getTasks().withType(JavaCompile.class).configureEach((JavaCompile javaCompile) ->
    javaCompile.doFirst((Task task) -> { })    
);

Adding Kotlin extensions such as follows doesn't help because the original functions have precedence:

fun <T : Task> T.doFirst(action: T.() -> Unit) {
    doFirst(action as Action<in Task>)
}

---

At first sight I don't see a simple way to solve this without changing Task radically. Any idea?

[Vampire]

Right now also not really besides adding a type parameter to Task and requiring all task classes to set it to itself or something like that which is probably what you meant with radical change and is probably quite an ugly change and might also make problems when extending tasks.

[eskatos]

That's what I had in mind yes. It would be breaking the task api for everyone 🤷