[GROOVY-10164] RootLoader cannot be set as system class loader in Java 12+

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 4.0.0-beta-1, 3.0.9, 2.5.16
• Assignee: Eric Milles
• Reporter: Eric Milles
• Created: 12/Jul/21 15:45
• Updated: 03/Feb/22 22:34
• Resolved: 16/Jul/21 16:48

Description

Support for -Djava.system.class.loader=org.codehaus.groovy.tools.RootLoader is missing for Java 12+. The constructor that accepts ClassLoader is private. See code excerpt below that tries to call this constructor using reflection.

java.lang.ClassLoader

    static synchronized ClassLoader initSystemClassLoader() {
        // ...
        String cn = System.getProperty("java.system.class.loader");
        if (cn != null) {
            try {
                // custom class loader is only supported to be loaded from unnamed module
                Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
                                           .getDeclaredConstructor(ClassLoader.class);
                scl = (ClassLoader) ctor.newInstance(builtinLoader);

java.lang.Error: class java.lang.ClassLoader (in module java.base) cannot access a member of class org.codehaus.groovy.tools.RootLoader with modifiers "private"
	at java.lang.ClassLoader.initSystemClassLoader(java.base@12.0.2/ClassLoader.java:1989)
	at java.lang.System.initPhase3(java.base@12.0.2/System.java:2132)
Caused by: java.lang.IllegalAccessException: class java.lang.ClassLoader (in module java.base) cannot access a member of class org.codehaus.groovy.tools.RootLoader with modifiers "private"
	at jdk.internal.reflect.Reflection.newIllegalAccessException(java.base@12.0.2/Reflection.java:376)
	at java.lang.reflect.AccessibleObject.checkAccess(java.base@12.0.2/AccessibleObject.java:639)
	at java.lang.reflect.Constructor.newInstanceWithCaller(java.base@12.0.2/Constructor.java:490)
	at java.lang.reflect.Constructor.newInstance(java.base@12.0.2/Constructor.java:481)
	at java.lang.ClassLoader.initSystemClassLoader(java.base@12.0.2/ClassLoader.java:1977)
	at java.lang.System.initPhase3(java.base@12.0.2/System.java:2132)