Kotlin 1.9.0: API files are not generated for a target if its leaf source set is empty

[arkivanov]

Kotlin version 1.9.0
Plugin version: 0.13.0-0.13.2
Android + JVM + JS + linuxX64 + All Apple targets

When running apiDump task, no .api files are generated under api/jvm or api/android folder, if the corresponding leaf source set (i.e. jvmMain and androidMain respectively) is empty. If there is some code present in e.g. jvmMain source set (or at least jvmMain/kotlin empty folder is present), then the jvm API file gets generated, similar situate with android.

Also, running apiCheck task fails:

A problem was found with the configuration of task ':instance-keeper:jvmApiCheck' (type 'KotlinApiCompareTask').
  - In plugin 'org.jetbrains.kotlinx.binary-compatibility-validator' type 'kotlinx.validation.KotlinApiCompareTask' property 'apiBuildDir' specifies directory '/Users/arkivanov/dev/workspace/Essenty/instance-keeper/build/api/jvm' which doesn't exist.

Works fine with version 0.12.1 and Kotlin 1.8.20.

[arkivanov]

After further investigation, it appears that adding the following code to a module's build.gradle.kts causes the issue described above.

tasks.withType<KotlinApiCompareTask> {
}

Attached a reproducer: reproducer.zip

[fzhinkin]

There's a problem with how we set enabled property during task's configuration:

binary-compatibility-validator/src/main/kotlin/BinaryCompatibilityValidatorPlugin.kt

Line 189 in 0dc8cd9

apiCheckEnabled(projectName, extension) && compilation.allKotlinSourceSets.any { it.kotlin.srcDirs.any { it.exists() } }

In the reproducer attached above, tasks.withType<KotlinApiCompareTask> triggers execution of the configuration block for "jvmApiBuild" task and at that point source sets are not yet filled/resolved/proper name for that action for the jvm compilation. There's only empty jvm source set, so we mark the task as disabled.

With the "normal" tasks flow, when the configuration block is executed for the build task, all source sets are already resolved for the JVM compilation and there should be some non-empty source set, for example, the common one/

[fzhinkin]

Related: #206