kspTestKotlin output seems to clobber kspKotlin output

[mvdbos]

I have two classes annotated with the same annotation. One in the main sourceset, one in the test sourceset.
In my processor, I use CodeGenerator to write the generated output files.

If I run only kspKotlin, the generated output is correctly placed in build/generated/ksp/src/main/kotlin/packagename/SomeFile.kt
If I subsequently run compileKotlin, the .class file for SomeFile.kt is correctly placed in the build/classes dir hierarchy. The generated source is untouched.

Now when I run kspTestKotlin, the generated source for the test sourceset is correctly placed in build/generated/ksp/src/xitest/kotlin/packagename/SomeTestFile.kt

Unfortunately the previously generated source for the main sourceset at build/generated/ksp/src/main is removed. Even the whole main subdir is removed. This not causing problems for running the code, since the .class files remain, but the IDE can now no longer find the source, which is very inconventient.

I did some digging in the code of Ksp, but it is not clear to me why this happens. Could you help me find the cause?

[mvdbos]

I did another test, and I can confirm that any invocation of KspTask clobbers build/generated/ksp.

When I manually add a subdir, e.g. build/generated/ksp/foo, and run either kspKotlin or kspTestKotlin, the dir build/generated/ksp get recreated.

Additionally, when I print the output dirs for the different KspTasks in Gradle like this, it indeed shows the output dir to be build/generated/ksp:

    withType<com.google.devtools.ksp.gradle.KspTask> {
        println(name)
        outputs.files.forEach { println(it.absolutePath) }
    }

[mvdbos]

When I do the same for tasks of type KotlinCompile, I see that the output dir is suffixed with the sourceset, which would prevent this clobbering from happening. Is this perhaps an idea to solve this?

[mvdbos]

Could it be that this causes it?

ksp/gradle-plugin/src/main/kotlin/com/google/devtools/ksp/gradle/KspSubplugin.kt

Line 112 in 64e7f0f

InternalTrampoline.KotlinCompileTaskData_register(kspTaskName, kotlinCompilation, project.provider { destinationDir })

[mvdbos]

Please have a look at #158. It addresses the issue for me, but I am not sure if this is the right way to adress this.

[ting-yuan]

A KspTask is basically a KotlinCompile with incremental = false. On each execution, the outputs are cleaned. KspTestKotlin shares the same destinationDir with KspKotlin and I guess this is why the outputs of KspKotlin is cleaned when running KspTestKotlin. Will make destinationDir task specific as well.