Add toolchain support to Gradle plugin

This aligns to the behaviour of toolchains in the Kotlin Gradle Plugin.
KGP will set jvmTarget and jdkHome based on the enabled toolchain,
assuming it hasn't been set elsewhere in the build script.

detekt-gradle-plugin/settings.gradle.kts

@@ -2,6 +2,8 @@ pluginManagement {
     includeBuild("../build-logic")
 }
 
+includeBuild("..")
+
 dependencyResolutionManagement {
     versionCatalogs {
         create("libs") {

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/Detekt.kt

@@ -19,13 +19,15 @@ import io.gitlab.arturbosch.detekt.invoke.DetektInvoker
 import io.gitlab.arturbosch.detekt.invoke.DisableDefaultRuleSetArgument
 import io.gitlab.arturbosch.detekt.invoke.FailFastArgument
 import io.gitlab.arturbosch.detekt.invoke.InputArgument
+import io.gitlab.arturbosch.detekt.invoke.JdkHomeArgument
 import io.gitlab.arturbosch.detekt.invoke.JvmTargetArgument
 import io.gitlab.arturbosch.detekt.invoke.LanguageVersionArgument
 import io.gitlab.arturbosch.detekt.invoke.ParallelArgument
 import io.gitlab.arturbosch.detekt.invoke.isDryRunEnabled
 import org.gradle.api.Action
 import org.gradle.api.file.ConfigurableFileCollection
 import org.gradle.api.file.Directory
+import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.FileTree
 import org.gradle.api.file.RegularFile
 import org.gradle.api.file.RegularFileProperty
@@ -38,6 +40,7 @@ import org.gradle.api.tasks.Classpath
 import org.gradle.api.tasks.Console
 import org.gradle.api.tasks.IgnoreEmptyDirectories
 import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputDirectory
 import org.gradle.api.tasks.InputFile
 import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.Internal
@@ -96,6 +99,11 @@ abstract class Detekt @Inject constructor(
         get() = jvmTargetProp.get()
         set(value) = jvmTargetProp.set(value)
 
+    @get:InputDirectory
+    @get:PathSensitive(PathSensitivity.ABSOLUTE)
+    @get:Optional
+    abstract val jdkHome: DirectoryProperty
+
     @get:Internal
     internal abstract val debugProp: Property<Boolean>
     var debug: Boolean
@@ -216,6 +224,7 @@ abstract class Detekt @Inject constructor(
             ClasspathArgument(classpath),
             LanguageVersionArgument(languageVersionProp.orNull),
             JvmTargetArgument(jvmTargetProp.orNull),
+            JdkHomeArgument(jdkHome),
             ConfigArgument(config),
             BaselineArgument(baseline.orNull),
             DefaultReportArgument(DetektReportType.XML, xmlReportFile.orNull),

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/DetektCreateBaselineTask.kt

@@ -17,6 +17,7 @@ import io.gitlab.arturbosch.detekt.invoke.InputArgument
 import io.gitlab.arturbosch.detekt.invoke.JvmTargetArgument
 import io.gitlab.arturbosch.detekt.invoke.ParallelArgument
 import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.FileTree
 import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.provider.Property
@@ -26,6 +27,7 @@ import org.gradle.api.tasks.Classpath
 import org.gradle.api.tasks.Console
 import org.gradle.api.tasks.IgnoreEmptyDirectories
 import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputDirectory
 import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.Optional
@@ -113,6 +115,11 @@ abstract class DetektCreateBaselineTask : SourceTask() {
         get() = jvmTargetProp.get()
         set(value) = jvmTargetProp.set(value)
 
+    @get:InputDirectory
+    @get:PathSensitive(PathSensitivity.ABSOLUTE)
+    @get:Optional
+    abstract val jdkHome: DirectoryProperty
+
     @get:Internal
     internal val arguments: Provider<List<String>> = project.provider {
         listOf(

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/internal/SharedTasks.kt

@@ -3,8 +3,12 @@ package io.gitlab.arturbosch.detekt.internal
 import io.gitlab.arturbosch.detekt.Detekt
 import io.gitlab.arturbosch.detekt.DetektCreateBaselineTask
 import io.gitlab.arturbosch.detekt.extensions.DetektExtension
+import org.gradle.api.JavaVersion
 import org.gradle.api.Project
+import org.gradle.api.plugins.JavaBasePlugin
+import org.gradle.api.plugins.JavaPluginExtension
 import org.gradle.api.tasks.TaskProvider
+import org.gradle.jvm.toolchain.JavaToolchainService
 
 internal fun Project.registerDetektTask(
     name: String,
@@ -40,6 +44,20 @@ internal fun Project.registerDetektTask(
             }
         }
 
+        project.plugins.withType(JavaBasePlugin::class.java) { _ ->
+            val toolchain = project.extensions.getByType(JavaPluginExtension::class.java).toolchain
+
+            // acquire a provider that returns the launcher for the toolchain
+            val service = project.extensions.getByType(JavaToolchainService::class.java)
+            val defaultLauncher = service.launcherFor(toolchain)
+            it.jdkHome.convention(defaultLauncher.map { launcher -> launcher.metadata.installationPath })
+            it.jvmTargetProp.convention(
+                defaultLauncher.map { launcher ->
+                    JavaVersion.toVersion(launcher.metadata.languageVersion.asInt()).toString()
+                }
+            )
+        }
+
         it.debugProp.set(provider { extension.debug })
         it.parallelProp.set(provider { extension.parallel })
         it.disableDefaultRuleSetsProp.set(provider { extension.disableDefaultRuleSets })
@@ -59,6 +77,20 @@ internal fun Project.registerCreateBaselineTask(
     configuration: DetektCreateBaselineTask.() -> Unit
 ): TaskProvider<DetektCreateBaselineTask> =
     tasks.register(name, DetektCreateBaselineTask::class.java) {
+        project.plugins.withType(JavaBasePlugin::class.java) { _ ->
+            val toolchain = project.extensions.getByType(JavaPluginExtension::class.java).toolchain
+
+            // acquire a provider that returns the launcher for the toolchain
+            val service = project.extensions.getByType(JavaToolchainService::class.java)
+            val defaultLauncher = service.launcherFor(toolchain)
+            it.jdkHome.convention(defaultLauncher.map { launcher -> launcher.metadata.installationPath })
+            it.jvmTargetProp.convention(
+                defaultLauncher.map { launcher ->
+                    JavaVersion.toVersion(launcher.metadata.languageVersion.asInt()).toString()
+                }
+            )
+        }
+
         it.config.setFrom(project.provider { extension.config })
         it.debug.set(project.provider { extension.debug })
         it.parallel.set(project.provider { extension.parallel })

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/invoke/CliArgument.kt

@@ -1,6 +1,7 @@
 package io.gitlab.arturbosch.detekt.invoke
 
 import io.gitlab.arturbosch.detekt.extensions.DetektReportType
+import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.RegularFile
 import java.io.File
@@ -21,6 +22,7 @@ private const val CREATE_BASELINE_PARAMETER = "--create-baseline"
 private const val CLASSPATH_PARAMETER = "--classpath"
 private const val LANGUAGE_VERSION_PARAMETER = "--language-version"
 private const val JVM_TARGET_PARAMETER = "--jvm-target"
+private const val JDK_HOME_PARAMETER = "--jdk-home"
 private const val BASE_PATH_PARAMETER = "--base-path"
 
 internal sealed class CliArgument {
@@ -58,6 +60,10 @@ internal data class JvmTargetArgument(val jvmTarget: String?) : CliArgument() {
     override fun toArgument() = jvmTarget?.let { listOf(JVM_TARGET_PARAMETER, it) }.orEmpty()
 }
 
+internal data class JdkHomeArgument(val jdkHome: DirectoryProperty) : CliArgument() {
+    override fun toArgument() = jdkHome.orNull?.let { listOf(JDK_HOME_PARAMETER, it.toString()) }.orEmpty()
+}
+
 internal data class BaselineArgument(val baseline: RegularFile?) : CliArgument() {
     override fun toArgument() = baseline?.let { listOf(BASELINE_PARAMETER, it.asFile.absolutePath) }.orEmpty()
 }