Add support for kotlinx-train (#257)

Author: dkhalanskyjb

build.gradle.kts

@@ -19,7 +19,11 @@ val modularJavaToolchainVersion by ext(project.property("java.modularToolchainVe
 
 allprojects {
     repositories {
+        addTrainRepositories(project)
         mavenCentral()
     }
+    tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
+        // outputs the compiler version to logs so we can check whether the train configuration applied
+        kotlinOptions.freeCompilerArgs += "-version"
+    }
 }
-

buildSrc/build.gradle.kts

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+import java.util.*
+
+plugins {
+    `kotlin-dsl`
+}
+
+val props = Properties().apply {
+    file("../gradle.properties").inputStream().use { load(it) }
+}
+
+// copy-pasted from `CommunityProjectsBuild`, see the explanation there
+fun RepositoryHandler.addTrainRepositories(project: Project) {
+    if (project.rootProject.properties["build_snapshot_train"]?.toString()?.toBoolean() == true) {
+        mavenLocal()
+    }
+    (project.rootProject.properties["kotlin_repo_url"] as? String)?.let(::maven)
+}
+
+// copy-pasted from `CommunityProjectsBuild`, but uses `props` to obtain the non-snapshot version, because
+// we don't have access to the properties defined in `gradle.properties` of the encompassing project
+val Project.kotlinVersion: String
+    get() = if (rootProject.properties["build_snapshot_train"]?.toString()?.toBoolean() == true) {
+        rootProject.properties["kotlin_snapshot_version"] as? String ?: error("kotlin_snapshot_version must be specified")
+    } else {
+        props.getProperty("defaultKotlinVersion")
+    }
+
+repositories {
+    mavenCentral()
+    gradlePluginPortal()
+    addTrainRepositories(project)
+}
+
+dependencies {
+    fun gradlePlugin(id: String, version: String): String = "$id:$id.gradle.plugin:$version"
+    implementation(gradlePlugin("org.jetbrains.kotlin.multiplatform", kotlinVersion))
+    implementation(gradlePlugin("org.jetbrains.kotlin.plugin.serialization", kotlinVersion))
+}

buildSrc/src/main/kotlin/CommunityProjectsBuild.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2016-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+@file:JvmName("CommunityProjectsBuild")
+
+import org.gradle.api.*
+import org.gradle.api.artifacts.dsl.*
+import org.gradle.api.artifacts.repositories.*
+import org.gradle.kotlin.dsl.*
+import java.util.logging.*
+
+private val LOGGER: Logger = Logger.getLogger("Kotlin settings logger")
+
+/**
+ * Functions in this file are responsible for configuring kotlinx-datetime build against a custom dev version
+ * of Kotlin compiler.
+ * Such configuration is used in a composite community build of Kotlin in order to check whether not-yet-released changes
+ * are compatible with our libraries (aka "integration testing that substitues lack of unit testing").
+ *
+ * Three parameters are used to configure the build:
+ * 1. `build_snapshot_train` - if true, the build is run against a snapshot train of Kotlin compiler
+ * 2. `kotlin_snapshot_version` - if specified, the build uses a custom Kotlin compiler version
+ * 3. `kotlin_repo_url` - if specified, the build uses a custom Kotlin compiler repository
+ *
+ * If `build_snapshot_train` is true, `kotlin_snapshot_version` must be present.
+ */
+
+/**
+ * Adds all the repositories that are needed for the Kotlin aggregate build.
+ */
+fun RepositoryHandler.addTrainRepositories(project: Project) {
+    if (project.rootProject.properties["build_snapshot_train"]?.toString()?.toBoolean() == true) {
+        mavenLocal()
+    }
+    // A kotlin-dev space repository with dev versions of Kotlin.
+    val devRepoUrl = project.rootProject.properties["kotlin_repo_url"] as? String ?: return
+    LOGGER.info("""Configured Kotlin Compiler repository url: '$devRepoUrl' for project ${project.name}""")
+    maven(devRepoUrl)
+}
+
+/**
+ * The version of Kotlin compiler to use in the Kotlin aggregate build.
+ */
+// unused, but may be useful in the future
+val Project.kotlinVersion: String
+    get() = if (rootProject.properties["build_snapshot_train"]?.toString()?.toBoolean() == true) {
+        rootProject.properties["kotlin_snapshot_version"] as? String ?: error("kotlin_snapshot_version must be specified")
+    } else {
+        rootProject.properties["defaultKotlinVersion"] as String
+    }

gradle.properties

@@ -5,7 +5,7 @@ group=org.jetbrains.kotlinx
 version=0.4.0
 versionSuffix=SNAPSHOT
 
-kotlinVersion=1.8.10
+defaultKotlinVersion=1.8.10
 dokkaVersion=1.8.10
 serializationVersion=1.5.0
 

settings.gradle.kts

@@ -4,11 +4,8 @@ pluginManagement {
         mavenCentral()
         gradlePluginPortal()
     }
-    val kotlinVersion: String by settings
     val dokkaVersion: String by settings
     plugins {
-        kotlin("multiplatform") version kotlinVersion
-        kotlin("plugin.serialization") version kotlinVersion
         id("org.jetbrains.dokka") version dokkaVersion
     }
 }