Kotlin Native Toolchain

The Kotlin Native Toolchain Gradle plugin installs the tools required for Kotlin/Native development. For example, installing clang for compiling C/C++ code to be compatible with Kotlin/Native.

It is easy to use, and cache-friendly.

Usage

Requirements

• Gradle 9.0+
• Kotlin 2.0.0+ (Versions of kotlin-native-prebuilt prior to 2.0.0 were not published to Maven Central.)

Using in a project

KNPT is a Gradle plugin and can be applied to a project as follows:

// build.gradle.kts
import dev.adamko.kntoolchain.kotlinNativePrebuiltDependencies

plugins {
  id("dev.adamko.kotlin-native-toolchain") version "x.x.x"
}

repositories {
  kotlinNativePrebuiltDependencies()
}

The installation directory can be obtained using knToolchain.provisionInstallation(), which returns a Provider<Path>. Important: the Provider must only be evaluated in the task execution phase.

val knToolchainUser by tasks.registering {
  val knToolchain = knToolchain.provisionInstallation()

  doLast {
    val knToolchain = knToolchain.get()
    println("knToolchain dir: {" + knToolchain.invariantSeparatorsPathString + "}")
  }
}

val knToolchainUser by tasks.registering {
  val knToolchain = knToolchain.provisionInstallation()
  inputs.dir(knToolchain)

  doLast {
    val knToolchain = knToolchain.get()
    println("knToolchain dir: " + knToolchain.invariantSeparatorsPathString)
  }
}

Using in settings

The dev.adamko.kotlin-native-toolchain plugin can also be applied as a Settings plugin, in a settings.gradle.kts file.

This has two advantages:

1. The kotlinNativePrebuiltDependencies() repository will be automatically added in dependencyResolutionManagement {}.
2. The plugin will register a task that will verify the checksums of the install distributions.

Configuration

The location of the installation directory can be configured in the DSL, or via the environment variable KN_TOOLCHAINS_DIR.

Motivation

C code must be compiled before it can be used in Kotlin/Native code.

K/N uses C compilation tools (for example, gcc and clang). Furthermore, specific versions of these tools are required. Installing older versions of these tools on a machine is sometimes challenging.

K/N's solution a pre-packaged distribution of the required tools, named 'kotlin-native-prebuilt'. Each K/N target and Kotlin version has a variant of the prebuilt distribution. Kotlin Gradle plugin provisions distributions into ~/.konan/, by default. The default install tool (see org.jetbrains.kotlin:kotlin-native-utils) is not cache-friendly, and is quite tightly integrated into KGP.

Other Gradle plugins could rely on KGP to provision a kotlin-native-prebuilt distribution, however, relying on KGP causes unnecessary coupling with K/N compilation, commonizer, and cinterop tasks. It's hard to get the coupling right. Problems manifest in strange compilation errors, (because KGP hasn't provisioned kotlin-native-prebuilt yet), or IntelliJ import errors (because it's hard to trigger KGP's provisioning).