Illegal private field access for field of inner type

Issue #231 resolved
Jesper Öqvist created an issue

ExtendJ 8.0.1-232-g3a88c80 Java SE 8

A test case using a builder pattern:

public class Ju1 {
  public static final Ju1 DEFAULT_ACTION =
      .withAction(new Action() {
        @Override public void doThing() {
          System.out.println("thing done");

  private final Action action;

  Ju1(Builder builder) {
    this.action = builder.action;

  private static Builder builder() {
    return new Builder();

  private static class Builder {
    private Action action;

    private Builder withAction(Action action) {
      this.action = action;
      return this;

    Ju1 build() {
      return new Ju1(this);

  void run() {

  public static void main(String[] args) {;

interface Action {
  void doThing();

Expected result: no runtime error.

Actual result:

Exception in thread "main" java.lang.IllegalAccessError: tried to access field Ju1$Builder.action from class Ju1
        at Ju1.<init>(
        at Ju1$
        at Ju1.<clinit>(

Comments (2)

  1. Jesper Öqvist reporter

    This issue is caused by an error in the VarAccess.requiresAccessor() attribute. The attribute uses the field name to determine if an accessor is required, but it should look at where the accessed field is declared instead:

      syn boolean VarAccess.requiresAccessor() {
        Variable v = decl();
        if (!(v instanceof FieldDeclarator)) {
          return false;
        FieldDeclarator f = (FieldDeclarator) v;
        if (f.isPrivate() && !hostType().hasField( {
          return true;
        if (f.isProtected() && !f.hostPackage().equals(hostPackage())
            && !hostType().hasField( {
          return true;
        return false;

    Compare to the MethodAccess.requiresAccessor() attribute:

      syn boolean MethodAccess.requiresAccessor() {
        MethodDecl decl = decl();
        if (decl.isPrivate() && decl.hostType() != hostType()) {
          return true;
        return decl.isProtected()
            && !decl.hostPackage().equals(hostPackage())
            && !hostType().hasMethod(decl);
  2. Jesper Öqvist reporter

    Fix error in VarAccess.requiresAccessor attribute

    The VarAccess.requiresAccessor attribute should test if the host type of a field declaration is different than the host type of the current access, rather than testing if a field with the same name is declared in the host type of the access.

    fixes #231 (bitbucket)

    → <<cset b805aab82ca8>>

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