fix #2899 does not work for shadowed String constants

[mictaege]

Upgrading from spoon 7.0.0 to 7.4.0. I faced problems that has been caused by the behavior described in the issues:

• EvalHelper#getCorrespondingRuntimeObject doesn't handle valid field references #2891 EvalHelper#getCorrespondingRuntimeObject doesn't handle valid field references
• bug: Default expression of field of shadow type is not initialized #2698 bug: Default expression of field of shadow type is not initialized

Both issues has been fixed with

• fix: improve getCorrespondingRuntimeObject/convertElementToRuntimeObject to handle shadow fields #2899 fix: improve getCorrespondingRuntimeObject/convertElementToRuntimeObject to handle shadow fields

but the fix does not work for String constants and I still get "not possible to transform to expression ..." errors.

Debugging the application I could see the following behavior:

With #2899 EvalHelper#getCorrespondingRuntimeObject has been extendend with this additional condition

if (field.getDefaultExpression() instanceof CtLiteral) {
  return ((CtLiteral) field.getDefaultExpression()).getValue();
}

But if the shadowed field is a String constant getDefaultExpression() returns null and therefore the Exception below will still be raised.

This is because the default expression has never been set in JavaReflectionTreeBuilder#visitField(Field):

if (modifiers.contains(ModifierKind.STATIC)
    && modifiers.contains(ModifierKind.PUBLIC)
    && field.getType().isPrimitive()
    ) {
      CtLiteral<Object> defaultExpression = factory.createLiteral(field.get(null));
      ctField.setDefaultExpression(defaultExpression);
}

For String constants field.getType().isPrimitive() is not true and so the whole if-condition turns to false and the default expression will not be set into the CtField.

Changing the if-condition to something like that

if (modifiers.contains(ModifierKind.STATIC)
    && modifiers.contains(ModifierKind.PUBLIC)
   && (field.getType().isPrimitive() || field.getType().getName().equals("java.lang.String"))
    ) {
      CtLiteral<Object> defaultExpression = factory.createLiteral(field.get(null));
      ctField.setDefaultExpression(defaultExpression);
}

in the debugger would make the whole condition true and then the default expression will be set correctly.

[monperrus]

Thanks a lot for the super detailed bug report.

It seems that the test case and the patch is super easy to write based on your extensive analysis. Would you give it a try in a pull-request? That would be awesome.

[mictaege]

Thanks a lot for for your prompt reply!

As you suggested I tried to make a pull-request to fix this issue.