Using KSP with Kotlin Multiplatform

[kamilr12]

Hi,

I am not able to use this api with Multiplatform projects. It works with Kotlin/JVM. Can you explain how to use custom processors in multiplatform projects?

[neetopia]

For now it only works with Kotlin/JVM.

[kamilr12]

Is it possible to add a custom processor as a dependency for only jvm target in multiplatform project?

[neetopia]

Cross posting from Slack:

can you elaborate your question? if you are using custom processor in mpp projects for JVM target only then processor will only see common and jvm specific source, if your processor does not rely on input from other platform source it should be fine.

[kamilr12]

Can you provide an example of adding custom processor for JVM target?

When I do something like this in my multiplatform project:

plugins {
    kotlin("multiplatform") version "1.4.0"
    id("kotlin-ksp") version "1.4.0-rc-dev-experimental-20200828"
    .....
}

kotlin {
    jvm()
    ....

    sourceSets {
        val commonMain by getting {
            dependencies {
            }
        }

        val commonTest by getting {
            dependencies {
                implementation(kotlin("test-common"))
                implementation(kotlin("test-annotations-common"))
            }
        }

        val jvmMain by getting {
            dependencies {
                implementation("my.custom.processor)
                ksp("my.custom.processor")
            }
        }

I get this gradle error:

 ksp("my.custom.processor")
                               ^ Type mismatch: inferred type is String but Action<KspExtension> was expected

And if i do this:

plugins {
    kotlin("multiplatform") version "1.4.0"
    id("kotlin-ksp") version "1.4.0-rc-dev-experimental-20200828"
    .....
}

kotlin {
    jvm()
    ....

    sourceSets {
        val commonMain by getting {
            dependencies {
            }
        }

        val commonTest by getting {
            dependencies {
                implementation(kotlin("test-common"))
                implementation(kotlin("test-annotations-common"))
            }
        }

        val jvmMain by getting {
            dependencies {
                implementation("my.custom.processor")
                "ksp"("my.custom.processor")
            }
        }

I have:

 "ksp"("my.custom.processor")
                           ^ Expression '"ksp"' of type 'String' cannot be invoked as a function. The function 'invoke()' is not found

Maybe some DSL for ksp is missing?

[neetopia]

might not directly relate to your issue, but the version number of ksp should be 1.4.0-dev-experimental-20200828

[kamilr12]

It's the same with 1.4.0-dev-experimental-20200828

[kamilr12]

I have managed to connect my custom processor to the jvm target in multiplatform project, here is the code snippet that worked:

plugins {
    kotlin("multiplatform") version "1.4.0"
    id("kotlin-ksp") version "1.4.0-rc-dev-experimental-20200828"
    .....
}

kotlin {
    jvm()
    ....

    sourceSets {
        val commonMain by getting {
            dependencies {
            }
        }

        val commonTest by getting {
            dependencies {
                implementation(kotlin("test-common"))
                implementation(kotlin("test-annotations-common"))
            }
        }

        val jvmMain by getting {
            dependencies {
                implementation("my.custom.processor")
                configurations["ksp"].dependencies.add(project.dependencies.create("my.custom.processor"))
            }
        }

For now it generates the code when I have only JVM and Android targets. Adding JavaScript fails the gradle execution.

Another thing I have spotted is that when you add any Native target, for example iOS, then this code:

plugins {
    kotlin("multiplatform") version "1.4.0"
    id("kotlin-ksp") version "1.4.0-dev-experimental-20200828"
}

Fails with this error:

* What went wrong:
A problem occurred configuring root project 'demo-project'.
> Failed to notify project evaluation listener.
   > Could not set unknown property 'incremental' for task ':compileKotlinIosArm64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileTestKotlinIosArm64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileKotlinIosX64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileTestKotlinIosX64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.

And it does not happen when line:

id("kotlin-ksp") version "1.4.0-dev-experimental-20200828"

is removed.

[Virelion]

Is there any way of launching KSP only on JVM target in Kotlin Multiplatform, while having other targets (native, js etc.)?

[neetopia]

Since currently only JVM target is supported, if you run it on a multi platform project, having other targets other than JVM should be fine.

[Virelion]

Sadly, it does not work.
I think there is some incompatibility on plugin level.
Adding

plugins {
    kotlin("multiplatform") version "1.4.0"
    id("kotlin-ksp") version "1.4.0-dev-experimental-20200828"
}

with configured native targets in project

kotlin {
    jvm()
    ios {}
    ...
}

results in error:

   > Could not set unknown property 'incremental' for task ':compileKotlinIosArm64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileTestKotlinIosArm64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileKotlinIosX64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.
   > Could not set unknown property 'incremental' for task ':compileTestKotlinIosX64' of type org.jetbrains.kotlin.gradle.tasks.KotlinNativeCompile.

[Virelion]

Launching KMP JVM processing is blocked now only by simple NPE.
Here PR with fix: #243
Can anyone review it?

[ting-yuan]

K/N is now supported by #541

[PhilipDukhov]

Should it be ready to test for iOS on 1.5.21-1.0.0-beta07?

I've tried following integration-tests/src/test/resources/kmp

And I'm adding it to my module like this:

val commonMain by getting {
    dependencies {
        configurations.get("ksp").dependencies.add(project(":test-processor"))
    }
}

On which I'm getting following sync error:
org.gradle.api.InvalidUserDataException: Cannot change dependencies of dependency configuration ':shared:kotlinCompilerPluginClasspathIosMain' after it has been resolved.

My sample project based on a clean KMP project

[atsushieno]

It is because commonMain block iterates for every platform, while keeping ksp dependencies. My project built with this conditional addition:

                if (configurations.get("ksp").dependencies.all { p -> p.name != ":myprocessor" })
                    configurations.get("ksp").dependencies.add(project(":myprocessor"))

[PhilipDukhov]

@atsushieno Tried pasting into my sample project, in my case configurations.get("ksp").dependencies.count() returns 0, so this solution doesn't work :(

[ting-yuan]

A tentative fix is on the way in #568. I haven't been able to reproduce it, though.

[atsushieno]

@PhilipDukhov Well, try changing the condition like "! any{...}" ? It's just standard Kotlin programming over collection.

[PhilipDukhov]

@atsushieno in my case this code only called once, and dependencies is empty, so all or ! any cannot help much here. Hope #568 will work

[ting-yuan]

I can reproduce with @PhilipDukhov's sample project now and verified that #568 fixes it. Thanks to @natario1's investigation, this is reproducible with Android Studio.