Add Gradle toolchain support

.circleci/config.pkl

@@ -141,11 +141,11 @@ local buildNativeJobs: Mapping<String, BuildNativeJob> = new {
 
 local gradleCheckJobs: Mapping<String, GradleCheckJob> = new {
   ["gradle-check-jdk11"] {
-    javaVersion = "11.0"
+    javaVersion = "11"
     isRelease = false
   }
   ["gradle-check-jdk17"] {
-    javaVersion = "17.0"
+    javaVersion = "17"
     isRelease = false
   }
 }

.circleci/config.yml

@@ -583,7 +583,7 @@ jobs:
     steps:
     - checkout
     - run:
-        command: ./gradlew --info --stacktrace check
+        command: ./gradlew --info --stacktrace check -DPKL_JVM_VERSION=11
         name: gradle check
     - run:
         command: |-
@@ -601,7 +601,7 @@ jobs:
     steps:
     - checkout
     - run:
-        command: ./gradlew --info --stacktrace check
+        command: ./gradlew --info --stacktrace check -DPKL_JVM_VERSION=17
         name: gradle check
     - run:
         command: |-
@@ -614,7 +614,7 @@ jobs:
     environment:
       LANG: en_US.UTF-8
     docker:
-    - image: cimg/openjdk:17.0
+    - image: cimg/openjdk:11.0
   bench:
     steps:
     - checkout

.circleci/jobs/GradleCheckJob.pkl

@@ -17,19 +17,19 @@ extends "GradleJob.pkl"
 
 import "package://pkg.pkl-lang.org/pkl-pantry/com.circleci.v2@1.1.0#/Config.pkl"
 
-javaVersion: "11.0"|"17.0"
+javaVersion: "11"|"17"
 
 steps {
   new Config.RunStep {
     name = "gradle check"
-    command = "./gradlew \(module.gradleArgs) check"
+    command = "./gradlew \(module.gradleArgs) check -DPKL_JVM_VERSION=\(javaVersion)"
   }
 }
 
 job {
   docker {
     new {
-      image = "cimg/openjdk:\(javaVersion)"
+      image = "cimg/openjdk:11.0"
     }
   }
 }

DEVELOPMENT.adoc

@@ -2,11 +2,9 @@
 :uri-gng: https://gng.dsun.org
 :uri-jenv: https://www.jenv.be
 :uri-intellij: https://www.jetbrains.com/idea/download/
-:uri-jdk: https://adoptopenjdk.net/releases.html
 
 == Setup
 
-. (mandatory) Install {uri-jdk}[OpenJDK 11 HotSpot] (as long as we support JDK11)
 . (recommended) Install {uri-intellij}[IntelliJ IDEA 2023.x] +
 To import the project into IntelliJ, go to File->Open and select the project's root directory.
 If the project is opened but not imported, look for a popup in the lower right corner

buildSrc/build.gradle.kts

@@ -1,5 +1,3 @@
-import org.jetbrains.kotlin.config.JvmTarget
-
 plugins {
   `kotlin-dsl`
 }
@@ -17,17 +15,6 @@ dependencies {
   implementation(files(libs.javaClass.superclass.protectionDomain.codeSource.location))
 }
 
-java {
-  sourceCompatibility = JavaVersion.VERSION_11
-  targetCompatibility = JavaVersion.VERSION_11
-}
-
 kotlin {
-  target {
-    compilations.configureEach {
-      kotlinOptions {
-        jvmTarget = "11"
-      }
-    }
-  }
+  jvmToolchain(11)
 }

buildSrc/src/main/kotlin/JvmToolchain.kt

@@ -0,0 +1,13 @@
+import org.gradle.jvm.toolchain.JavaLanguageVersion
+import org.gradle.jvm.toolchain.JvmVendorSpec
+
+private const val JDK_VERSION = 11
+
+val jvmToolchainVersion: JavaLanguageVersion
+    get() {
+        val jvmVersion = System.getProperty("PKL_JVM_VERSION")?.toInt() ?: JDK_VERSION
+        return JavaLanguageVersion.of(jvmVersion)
+    }
+
+val jvmToolchainVendor: JvmVendorSpec 
+    get() = JvmVendorSpec.ADOPTIUM

buildSrc/src/main/kotlin/pklAllProjects.gradle.kts

@@ -22,15 +22,8 @@ configurations {
   }
 }
 
-plugins.withType(JavaPlugin::class).configureEach {
-  val java = project.extensions.getByType<JavaPluginExtension>()
-  java.sourceCompatibility = JavaVersion.VERSION_11
-  java.targetCompatibility = JavaVersion.VERSION_11
-}
-
 tasks.withType<KotlinCompile>().configureEach {
   kotlinOptions {
-    jvmTarget = "11"
     freeCompilerArgs = freeCompilerArgs + listOf("-Xjsr305=strict", "-Xjvm-default=all")
   }
 }

buildSrc/src/main/kotlin/pklFatJar.gradle.kts

@@ -43,7 +43,7 @@ val relocations = mapOf(
   // pkl-doc dependencies
   "org.commonmark." to "org.pkl.thirdparty.commonmark.",
   "org.jetbrains." to "org.pkl.thirdparty.jetbrains.",
-  
+
   // pkl-config-java dependencies
   "io.leangen.geantyref." to "org.pkl.thirdparty.geantyref.",
 
@@ -54,6 +54,13 @@ val relocations = mapOf(
   "com.squareup.kotlinpoet." to "org.pkl.thirdparty.kotlinpoet.",
 )
 
+java {
+  toolchain {
+    languageVersion.set(jvmToolchainVersion)
+    vendor.set(jvmToolchainVendor)
+  }
+}
+
 val nonRelocations = listOf("com/oracle/truffle/")
 
 tasks.shadowJar {
@@ -117,7 +124,7 @@ val validateFatJar by tasks.registering {
       val path = fileDetails.relativePath.pathString
       if (!(fileDetails.isDirectory ||
           path.startsWith("org/pkl/") ||
-          path.startsWith("META-INF/") || 
+          path.startsWith("META-INF/") ||
           nonRelocations.any { path.startsWith(it) })) {
         // don't throw exception inside `visit` 
         // as this gives a misleading "Could not expand ZIP" error message

buildSrc/src/main/kotlin/pklJavaLibrary.gradle.kts

@@ -17,6 +17,15 @@ val libs = the<LibrariesForLibs>()
 java {
   withSourcesJar() // creates `sourcesJar` task
   withJavadocJar()
+
+  toolchain {
+    languageVersion.set(jvmToolchainVersion)
+    vendor.set(jvmToolchainVendor)
+  }
+}
+
+tasks.withType<JavaExec>().configureEach {
+  javaLauncher.set(javaToolchains.launcherFor(java.toolchain))
 }
 
 artifacts {

buildSrc/src/main/kotlin/pklKotlinLibrary.gradle.kts

@@ -24,6 +24,11 @@ tasks.compileKotlin {
   enabled = true // disabled by pklJavaLibrary
 }
 
+kotlin.jvmToolchain {
+  languageVersion.set(jvmToolchainVersion)
+  vendor.set(jvmToolchainVendor)
+}
+
 spotless {
   kotlin {
     ktfmt(libs.versions.ktfmt.get()).googleStyle()

buildSrc/src/main/kotlin/pklKotlinTest.gradle.kts

@@ -16,6 +16,11 @@ dependencies {
   testRuntimeOnly(buildInfo.libs.findLibrary("junitEngine").get())
 }
 
+kotlin.jvmToolchain {
+  languageVersion.set(jvmToolchainVersion)
+  vendor.set(jvmToolchainVendor)
+}
+
 tasks.withType<Test>().configureEach {
   val testTask = this
 

settings.gradle.kts

@@ -27,18 +27,17 @@ pluginManagement {
   }
 }
 
+plugins {
+    id("org.gradle.toolchains.foojay-resolver-convention") version "0.8.0"
+}
+
 @Suppress("UnstableApiUsage")
 dependencyResolutionManagement {
   repositories {
     mavenCentral()
   }
 }
 
-val javaVersion = JavaVersion.current()
-require(javaVersion.isJava11Compatible) {
-  "Project requires Java 11 or higher, but found ${javaVersion.majorVersion}."
-}
-
 if (gradle.startParameter.taskNames.contains("updateDependencyLocks") ||
   gradle.startParameter.taskNames.contains("uDL")
 ) {