HHH-13682 Generate Java 13/14 bytecode for tests when building with JDK13/14

gradle/base-information.gradle

@@ -13,6 +13,21 @@ ext {
 	jpaVersion = new JpaVersion('2.2')
 }
 
+if ( JavaVersion.current() == JavaVersion.VERSION_HIGHER ) {
+	// This JDK is not supported by Gradle.
+	// Use a hack to retrieve the major as a string.
+
+	// This only works for Java 9+ (we're at least on Java 13 here).
+	def major = System.getProperty( 'java.specification.version' )
+	logger.warn( "[WARN] The Java version '$major' is not supported by gradle." )
+
+	ext.testedJavaVersion = major
+}
+else {
+	// This JDK is supported by Gradle.
+	ext.testedJavaVersion = JavaVersion.current()
+}
+
 group = 'org.hibernate'
 version = project.ormVersion.fullName
 

gradle/java-module.gradle

@@ -38,10 +38,6 @@ ext {
 	forbiddenAPITargetJDKCompatibility = '11'
 }
 
-
-sourceCompatibility = project.baselineJavaVersion
-targetCompatibility = project.baselineJavaVersion
-
 if ( !project.description ) {
 	project.description = "The Hibernate ORM $project.name module"
 }
@@ -116,8 +112,20 @@ dependencies {
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // Compilation
 
-tasks.withType(JavaCompile) {
+tasks.withType( JavaCompile ) {
 	options.encoding = 'UTF-8'
+	sourceCompatibility = project.baselineJavaVersion
+	targetCompatibility = project.baselineJavaVersion
+}
+
+if ( project.baselineJavaVersion != project.testedJavaVersion ) {
+	logger.info( "Forcing the target bytecode version for test classes to '$project.testedJavaVersion'" )
+
+	tasks.compileTestJava {
+		// For *tests only*, generate bytecode matching the Java version currently in use.
+		// This allows testing bytecode enhancement on the latest Java versions (13, 14, ...).
+		targetCompatibility = project.testedJavaVersion
+	}
 }
 
 task compile(dependsOn: [compileJava, processResources, compileTestJava, processTestResources] )