I’m having some weird issue when trying to add a g...

# gradle

[Matheus Finatti]

I’m having some weird issue when trying to add a gradle plugin to a convention plugin
I have a build-logic module with a bunch of convention plugins
In build.gradle.kts I tried adding a gradle plugin like such:

plugins {
    `kotlin-dsl`
    `kotlin-dsl-precompiled-script-plugins`
}

group = "buildlogic"

repositories {
    mavenCentral()
    google()
    maven ("<https://s01.oss.sonatype.org/content/repositories/releases/>")
}

java {
    sourceCompatibility = JavaVersion.VERSION_11
    targetCompatibility = JavaVersion.VERSION_11
}

dependencies {
    implementation(libs.gradlePlugin.android)
    implementation(libs.gradlePlugin.kotlin)
    implementation(libs.detekt)
    implementation(libs.kmm.spm) // This one is throwing an exception
}

My version catalog looks like this:

[versions]
detekt = "1.22.0"
kmm-spm = "2.1.1"

[libraries]
detekt = { module = "io.gitlab.arturbosch.detekt:detekt-gradle-plugin", version.ref = "detekt" }
kmm-spm = { group = "io.github.luca992.multiplatform-swiftpackage", name = "io.github.luca992.multiplatform-swiftpackage.gradle.plugin", version.ref = "kmm-spm" }

Detekt works fine, but kmm-spm does not.
I get an exception when syncing:

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':build-logic:generateExternalPluginSpecBuilders'.
	[...]
Caused by: java.lang.NullPointerException: implementationClass must not be null
	at org.gradle.kotlin.dsl.codegen.PluginIdExtensionsKt$pluginEntriesFrom$1$2.invoke(PluginIdExtensions.kt:105)
	at org.gradle.kotlin.dsl.codegen.PluginIdExtensionsKt$pluginEntriesFrom$1$2.invoke(PluginIdExtensions.kt)

Could this be an issue with Gradle, or with the plugin I’m trying to import?
plugin in question: https://github.com/luca992/multiplatform-swiftpackage

Thanks in advance!

[Adam S]

kmm-spm = { group = "io.github.luca992.multiplatform-swiftpackage", name = "io.github.luca992.multiplatform-swiftpackage.gradle.plugin", version.ref = "kmm-spm"

this looks like a mistake, I guess this Maven coordinates of the the Gradle plugin marker, not the actual plugin implementation

[Matheus Finatti]

This is the only way I could find that would make gradle actually download the plugin.
I’ve checked my .gradle/caches and all the contents are there

[Adam S]

hmm yes, you’re right. I can’t see the plugin marker in Maven, and the error doesn’t match what happens when the wrong coordinates are used https://stackoverflow.com/q/74817692/4161471

[Adam S]

do you know if the plugin is published to the Gradle Plugin Portal?

[Matheus Finatti]

No, it’s published here:

maven ("<https://s01.oss.sonatype.org/content/repositories/releases/>")

[Adam S]

I think that’s the Maven Central URL, so while it’s completely unrelated to your problem, you could remove the URL from the repos

repositories {
    mavenCentral()
    google()
//    maven("<https://s01.oss.sonatype.org/content/repositories/releases/>")
}

[Adam S]

hmmm, very weird. Looking at the plugin code it’s using afterEvaluate {} which could cause problems, and it requires that the Kotlin Multiplatform plugin is applied rather than reacting to it.

What are the contents of your convention plugin where you’re applying the plugin? What’s the full stacktrace? Are there any com.chromaticnoise lines in there?

[Matheus Finatti]

mport buildlogic.Namespace
import buildlogic.Versions
import org.jetbrains.kotlin.gradle.plugin.mpp.apple.XCFramework

plugins {
    id("kotlin-multiplatform")
    id("com.android.library")
}

group = "mp"

kotlin {
    android()
    val frameworkName = name
    val xcf = XCFramework(frameworkName)
    listOf(
        iosArm64(),
        iosSimulatorArm64(),
    ).forEach { target ->
        target.binaries.framework {
            baseName = frameworkName
            xcf.add(this)
        }
    }

    sourceSets {
        val commonMain by getting
        val commonTest by getting {
            dependencies {
                implementation(kotlin("test"))
            }
        }
        val androidMain by getting
        val androidTest by getting
        val iosArm64Main by getting
        val iosSimulatorArm64Main by getting
        val iosMain by creating {
            dependsOn(commonMain)
            iosArm64Main.dependsOn(this)
            iosSimulatorArm64Main.dependsOn(this)
        }
        val iosArm64Test by getting
        val iosSimulatorArm64Test by getting
        val iosTest by creating {
            dependsOn(commonTest)
            iosArm64Test.dependsOn(this)
            iosSimulatorArm64Test.dependsOn(this)
        }
    }
}

android {
    namespace = "${Namespace.shared}.core"
    compileSdk = Versions.compileSdk
    defaultConfig {
        minSdk = Versions.minSdk
    }
}

This is the convention plugin, I haven’t added multiplatform-swiftpackage yet, because it fails before

[Vampire]

It's simply that the io.github.luca992.multiplatform-swiftpackage plugin is broken.

[Vampire]

If you download the jar and look into META-INF\gradle-plugins\com.chromaticnoise.multiplatform-swiftpackage.properties you find a property implementationClass but not a property implementation-class which should be there.

[Adam S]

https://github.com/ge-org/multiplatform-swiftpackage/blob/8d7c25ecc19841d4af515db885ae3426f7f32274/src/main/resources/META-INF/gradle-plugins/com.chromaticnoise.multiplatform-swiftpackage.properties

[Matheus Finatti]

Nice one, so just replacing it to implementation-class would fix the issue?

[Matheus Finatti]

Will it still work when adding to a plugins{} block in a regular build.gradle.kts?

[Vampire]

I don't know when this code path is hit, so no idea.
But yeah, fixing the properties file should probably fix the problem.

[Vampire]

Btw. kotlin-dsl already applies kotlin-dsl-precompiled-script-plugins internally, there is no need to apply it explicitly.

[Adam S]

Gradle Kotlin DSL will do some code gen to generate accessors for any plugins that it finds in buildSrc, or equivalent, that’s why the exception is in org.gradle.kotlin.dsl.codegen.PluginIdExtensionsKt. So given that the plugin is released at all, yeah, I think it should work in normal plugins {} blocks.

[Matheus Finatti]

Awesome, thanks a lot

[Adam S]

I’d say this is an edgecase that Gradle could handle better. It would be more helpful if Gradle didn’t error out, and logged a message instead.

[Adam S]

to actually fix the issue, the plugin author could

1. remove src/main/resources/META-INF/gradle-plugins/com.chromaticnoise.multiplatform-swiftpackage.properties
2. change the publishing coordinates of the plugin to be different to the plugin marker ID
then the gradlePlugin {} config will make the plugin ID work automatically https://github.com/ge-org/multiplatform-swiftpackage/blob/8d7c25ecc19841d4af515db885ae3426f7f32274/build.gradle.kts#L52-L59

[Matheus Finatti]

I will pass it forward. Thanks for the support!