Add TapmocExtension.gradle()

tapmoc-gradle-plugin/api/tapmoc-gradle-plugin.api

@@ -17,8 +17,11 @@ public abstract interface class tapmoc/TapmocExtension {
 	public abstract fun checkDependencies ()V
 	public abstract fun checkDependencies (Ltapmoc/Severity;)V
 	public abstract fun checkRuntimeDependencies (Ltapmoc/Severity;)V
+	public abstract fun gradle (Ljava/lang/String;)V
 	public abstract fun java (I)V
+	public abstract fun javaVersionForGradle (Ljava/lang/String;)I
 	public abstract fun kotlin (Ljava/lang/String;)V
+	public abstract fun kotlinVersionForGradle (Ljava/lang/String;)Ljava/lang/String;
 }
 
 public abstract class tapmoc/TapmocPlugin : org/gradle/api/Plugin {

tapmoc-gradle-plugin/src/main/kotlin/tapmoc/TapmocExtension.kt

@@ -28,6 +28,34 @@ interface TapmocExtension {
    */
   fun kotlin(version: String)
 
+  /**
+   * Configures the minimal Gradle version supported.
+   *
+   * This method:
+   * - Calls [kotlin] with the compatible Kotlin version as described in the [Gradle compatibility matrix](https://docs.gradle.org/current/userguide/compatibility.html#kotlin).
+   * - Calls [java] with the compatible Java version as described in the [Gradle compatibility matrix](https://docs.gradle.org/current/userguide/compatibility.html#java_runtime).
+   *
+   * @param gradleVersion the Gradle version to target, specified as a string. Example: "8.14".
+   */
+  fun gradle(gradleVersion: String)
+
+  /**
+   * Returns the minimal version of Java required to run the given Gradle version.
+   *
+   * Gradle versions between 2.0 and 8.14 require Java 8.
+   * Gradle 9.0.0 requires Java 17.
+   *
+   * See https://docs.gradle.org/current/userguide/compatibility.html#java
+   */
+  fun javaVersionForGradle(gradleVersion: String): Int
+
+  /**
+   * Returns the languageVersion used to compile Kotlin build scripts.
+   *
+   * See https://docs.gradle.org/current/userguide/compatibility.html#kotlin
+   */
+  fun kotlinVersionForGradle(gradleVersion: String): String
+
   @Deprecated("Use checkDependencies instead.", ReplaceWith("checkDependencies(severity)"))
   fun checkApiDependencies(severity: Severity)
 

tapmoc-gradle-plugin/src/main/kotlin/tapmoc/internal/TapmocExtensionImpl.kt

@@ -87,6 +87,20 @@ internal abstract class TapmocExtensionImpl(private val project: Project) : Tapm
     project.configureKotlinCompatibility(version)
   }
 
+  override fun gradle(gradleVersion: String) {
+    val major = parseGradleMajorVersion(gradleVersion)
+    kotlin(kotlinVersionForGradle(major))
+    java(javaVersionForGradle(major))
+  }
+
+  override fun javaVersionForGradle(gradleVersion: String): Int {
+    return javaVersionForGradle(parseGradleMajorVersion(gradleVersion))
+  }
+
+  override fun kotlinVersionForGradle(gradleVersion: String): String {
+    return kotlinVersionForGradle(parseGradleMajorVersion(gradleVersion))
+  }
+
   override fun checkDependencies() {
     checkDependencies(Severity.ERROR)
   }

tapmoc-gradle-plugin/src/main/kotlin/tapmoc/internal/gradle.kt

@@ -0,0 +1,49 @@
+package tapmoc.internal
+
+internal fun kotlinVersionForGradle(major: Int): String {
+  /**
+   * We use `languageVersion` as the compatible Kotlin version.
+   *
+   * Note: `languageVersion` is lower than the Kotlin embedded version.
+   * - Gradle may bump the Kotlin embedded version in Gradle minor releases.
+   * - The Kotlin `languageVersion` is only bumped in major releases.
+   *
+   * This is to avoid the occasional Kotlin source-breaking changes to break existing
+   * builds in a minor Gradle release.
+   *
+   * See https://docs.gradle.org/current/userguide/compatibility.html#kotlin
+   *
+   */
+  return when {
+    major >= 9 -> "2.2.0"
+    major >= 8 -> "1.8.0"
+    major >= 7 -> "1.4.0"
+    else -> error("Gradle versions < 7.0 are not supported (found '$major')")
+  }
+}
+
+internal fun javaVersionForGradle(major: Int): Int {
+  /**
+   * See https://docs.gradle.org/current/userguide/compatibility.html#java
+   */
+  return when {
+    major >= 9 -> 17
+    major >= 5 -> 8
+    else -> error("Gradle versions < 5 are not supported (found '$major')")
+  }
+}
+
+internal fun parseGradleMajorVersion(gradleVersion: String): Int {
+  val c = gradleVersion.split('.')
+  check (c.isNotEmpty()) {
+    "Tapmoc: gradleVersion should be in the form `major[.minor[.patch]]` (found '$gradleVersion')"
+  }
+
+  val major = c.get(0).toIntOrNull()
+
+  check (major != null) {
+    "Tapmoc: major version must be an integer (found '$major' in '$gradleVersion')"
+  }
+
+  return major
+}

tests/gradle-plugin/build.gradle.kts

@@ -6,15 +6,14 @@ plugins {
 }
 
 tapmoc {
-  // Gradle 8.3 uses Kotlin 1.9
-  java(11)
-  kotlin("1.9.0")
+  // Gradle 8.3 uses Kotlin languageVersion 1.8
+  gradle("8.3")
   checkDependencies()
 }
 
 checkPublication {
-  jvmTarget.set(11)
-  kotlinMetadataVersion.set("1.9.0")
+  jvmTarget.set(8)
+  kotlinMetadataVersion.set("1.8.0")
 }
 
 dependencies {