Fix #228: reduce parallelism in task and increase parallelism between…

… tasks (#246)

* Enable configuration cache
* Remove parallelism inside compatTest tasks.
* Remove kotlin-dsl and only use what is used in this project (kotlin-dsl dependency and sam with receiver). This prevents us from needing to fight with kotlin-dsl overriding language versions.
* Move to new KGP DSL for setting up versions. (kotlinOptions to compilerOptions)
* Make compatTest past without kotlin-dsl
* Revert to kotlin-dsl, it does too many things apart from the forceful version.
* Fix kotlin versioning
* Simplify
* Un-nest
* Make a change to trigger rerun of tests

build.gradle.kts

@@ -1,6 +1,7 @@
 import org.gradle.initialization.IGradlePropertiesLoader.ENV_PROJECT_PROPERTIES_PREFIX
 import org.gradle.initialization.IGradlePropertiesLoader.SYSTEM_PROJECT_PROPERTIES_PREFIX
-import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
 
 plugins {
     `kotlin-dsl`
@@ -161,28 +162,44 @@ sourceSets {
     }
 }
 
-tasks {
-    afterEvaluate {
-        // This needs to be in an afterEvaluate block,
-        // because otherwise KotlinDslCompilerPlugins would win, and override what we've set to Kotlin 1.8.
-        withType<KotlinCompile>().configureEach {
-            kotlinOptions.jvmTarget = JavaVersion.VERSION_1_8.toString()
-            // Supporting Gradle 6.0+ needs to use Kotlin 1.3.
-            // See https://docs.gradle.org/current/userguide/compatibility.html
-            kotlinOptions.apiVersion = "1.3"
-            // Theoretically we could use newer language version here,
-            // but sadly the @kotlin.Metadata created on the classes would be incompatible with Kotlin 1.3 consumers.
-            kotlinOptions.languageVersion = "1.3"
-            doFirst {
-                if (kotlinOptions.apiVersion == "1.3") {
-                    // Suppress "Language version 1.3 is deprecated and its support will be removed in a future version of Kotlin".
-                    kotlinOptions.freeCompilerArgs += "-Xsuppress-version-warnings"
-                } else {
-                    TODO("Remove -Xsuppress-version-warnings suppression, or change the condition to ${kotlinOptions.languageVersion}")
-                }
+kotlin.target.compilations.configureEach {
+    // Supporting Gradle 6.0+ needs to use Kotlin 1.3.
+    // See https://docs.gradle.org/current/userguide/compatibility.html
+    // For future maintainer: Kotlin 1.9.0 dropped support for Kotlin 1.3, it'll only support 1.4+.
+    // This means Gradle 7.0 will be the lowest supportable version for plugins.
+    val usedKotlinVersion = @Suppress("DEPRECATION") KotlinVersion.KOTLIN_1_3
+
+    compilerOptions.configure {
+        // Gradle fully supports running on Java 8: https://docs.gradle.org/current/userguide/compatibility.html,
+        // so we should allow users to do that too.
+        jvmTarget = JvmTarget.fromTarget(JavaVersion.VERSION_1_8.toString())
+
+        // Suppress "Language version 1.3 is deprecated and its support will be removed in a future version of Kotlin".
+        freeCompilerArgs.add("-Xsuppress-version-warnings")
+    }
+    compileTaskProvider.configure {
+        // These two (api & lang) needs to be here instead of in compilations.compilerOptions.configure { },
+        // to prevent KotlinDslCompilerPlugins overriding to Kotlin 1.8.
+        compilerOptions.apiVersion = usedKotlinVersion
+        // Theoretically we could use newer language version here,
+        // but sadly the @kotlin.Metadata created on the classes would be incompatible with older consumers.
+        compilerOptions.languageVersion = usedKotlinVersion
+
+        // Validate that we're using the right version.
+        doFirst {
+            val api = compilerOptions.apiVersion.get()
+            val language = compilerOptions.languageVersion.get()
+            if (api != usedKotlinVersion || language != usedKotlinVersion) {
+                TODO(
+                    "There's mismatch between configured and actual versions:\n" +
+                            "apiVersion=${api}, languageVersion=${language}, configured=${usedKotlinVersion}."
+                )
             }
         }
     }
+}
+
+tasks {
     shadowJar {
         exclude("META-INF/maven/**", "META-INF/proguard/**", "META-INF/*.kotlin_module")
         manifest {
@@ -228,7 +245,7 @@ tasks {
     withType<Test>().configureEach {
         dependsOn(shadowJar)
         useJUnitPlatform()
-        maxParallelForks = 8
+        maxParallelForks = if (name.startsWith("compatTest")) 1 else 8
     }
     withType<Test>().matching { it.name.startsWith("compatTest") }.configureEach {
         systemProperty("plugin.version", project.version)

gradle.properties

@@ -1,2 +1,3 @@
 org.gradle.caching=true
 org.gradle.parallel=true
+org.gradle.configuration-cache=true

src/compatTest/kotlin/io/github/gradlenexus/publishplugin/TestExtensions.kt

@@ -20,13 +20,13 @@ import java.nio.file.Files
 import java.nio.file.Path
 
 fun Path.write(text: String): Path {
-    Files.createDirectories(parent)
-    toFile().writeText(text)
+    Files.createDirectories(this.parent)
+    this.toFile().writeText(text)
     return this
 }
 
 fun Path.append(text: String): Path {
-    Files.createDirectories(parent)
-    toFile().appendText(text)
+    Files.createDirectories(this.parent)
+    this.toFile().appendText(text)
     return this
 }