"Unresolved reference: implementation" by using subprojects in kotlin-gradle

Question

I want to split my project into subprojects. The default Gradle setting from the IntelliJ IDE is:

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.3.50"
}

group = "project"
version = "0.0.1-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    implementation(kotlin("stdlib-jdk8"))
}

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "1.8"
}

That setting compiles. ButI don't want repeat that code in every subproject. So I changed the build.gradle.kts to

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

subprojects {
    plugins {
        kotlin("jvm") version "1.3.50"
    }

    group = "project"
    version = "0.0.1-SNAPSHOT"

    repositories {
        mavenCentral()
    }

    dependencies {
        implementation(kotlin("stdlib-jdk8"))
    }

    tasks.withType<KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
    }
}

but I get the exception:

e: C:[...]\build.gradle.kts:1:12: Unresolved reference: jetbrains e: C:[...]\build.gradle.kts:16:9: Unresolved reference: implementation e: C:[...]\build.gradle.kts:19:20: Unresolved reference: KotlinCompile e: C:[...]\build.gradle.kts:19:35: Type mismatch: inferred type is () -> Unit but Class<TypeVariable(S)!>! was expected e: C:[...]\build.gradle.kts:20:9: Unresolved reference: kotlinOptions

FAILURE: Build failed with an exception.

Where: Build file 'C:[...]\build.gradle.kts' line: 1

What went wrong: Script compilation errors:

Line 01: import org.jetbrains.kotlin.gradle.tasks.KotlinCompile ^ Unresolved reference: jetbrains

Line 16: implementation(kotlin("stdlib-jdk8")) ^ Unresolved reference: implementation

Line 19: tasks.withType { ^ Unresolved reference: KotlinCompile

Line 19: tasks.withType { ^ Type mismatch: inferred type is () -> Unit but Class<TypeVariable(S)!>! was expected

Line 20: kotlinOptions.jvmTarget = "1.8" ^ Unresolved reference: kotlinOptions

5 errors

Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

Get more help at https://help.gradle.org

BUILD FAILED in 1s

I think there is an easy syntax error, but I can't find it.

Cisco · Accepted Answer · 2022-02-22 20:27:54Z

35

Not sure how you're not also getting an error by nesting the plugins { } block under subprojects { } As stated in Limitations of the plugins DSL:

The plugins {} block must also be a top level statement in the buildscript. It cannot be nested inside another construct (e.g. an if-statement or for-loop).

So to fix your issues, move the plugins {} to the top and imperatively apply the plugins in the subprojects {} block:

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.3.50" apply false
}

subprojects {
    apply {
        plugin("org.jetbrains.kotlin.jvm")
    }

    group = "project"
    version = "0.0.1-SNAPSHOT"

    repositories {
        mavenCentral()
    }

    val implementation by configurations

    dependencies {
        implementation(kotlin("stdlib-jdk8"))
    }

    tasks.withType<KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
    }
}

You can read more about the apply false part in the Method details of PluginDependenciesSpec which is the type/scope of the plugins {} block.

You can read more about the val implementation by configurations part in the Understanding what to do when type-safe model accessors are not available

edited Feb 22, 2022 at 20:27

answered Nov 2, 2019 at 14:19

Cisco

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1 Comment

royalstream Over a year ago

You singlehandedly saved one of my projects. All the documentation I found on Gradle's website was completely useless. Your post, on the other hand, had me up and running in five minutes. Gradle should fire all their documentation department and hire you instead.

Braian Coronel · Accepted Answer · 2021-01-22 01:46:54Z

Is important to define the repositories in settings.gradle.kts (project) so that the dependencies of the subprojects are recognized.

settings.gradle.kts (project)

pluginManagement {
    repositories {
        maven("https://dl.bintray.com/kotlin/kotlin-eap")
        mavenCentral()
        maven("https://plugins.gradle.org/m2/")
    }
}
rootProject.name = "project"

include("app")

build.gradle.kts (project)

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

        plugins {
            java
            kotlin("jvm") version "1.4-M3" apply false
        }

subprojects {
    apply {
        plugin("org.jetbrains.kotlin.jvm")
    }

    repositories {
        maven("https://dl.bintray.com/kotlin/kotlin-eap")
        mavenCentral()
    }

    val implementation by configurations

    dependencies {
        implementation(kotlin("stdlib-jdk8"))
    }

    tasks.withType<KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
    }
}

To define plugins for each submodule separately use the lambda apply { plugin("pluginId") }

build.gradle.kts (:app)

apply {
    plugin("org.jetbrains.kotlin.jvm")
}

dependencies {
    implementation(kotlin("stdlib-jdk8"))
}

GL

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