[GROOVY-9302] @Delegate works incorrectly with inheritance and final methods

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.5.2, 2.5.8
• Assignee: Unassigned
• Reporter: Basil Peace
• Created: 03/Nov/19 18:07
• Updated: 03/Nov/19 23:49

Description

In the following situation:

• Two class hierarchies: Child1 <|-- Child2 and Parent1 <|-- Parent0
• Classes from the second hierarchy delegate to the first ones with constructions:
  • in parent:

@Delegate(includeTypes = [I1])
abstract C getChild()

• • in child:

@Delegate(includeTypes = [I2])
@Override
abstract C getChild()

(in other words, all calls are delegated to the same instance, just on different levels of hierarchy)

• Methods in the first hierarchy are marked final

compiler gives an error:

 

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
com\example\Parent0.groovy: -1: You are not allowed to override the final method method1() from class 'com.example.Parent1'.
 @ line -1, column -1.
1 error

Repository reproducing it: https://github.com/grv87/groovy-delegate-and-inheritance

 

Error presence depends on compilation order. If I rename Parent0 to Parent2, error disappears.

So, as I see, the problem is that when @Delegate is applied to Parent0, it doesn't detect that some methods are already added by another @Delegate to it's super, Parent1.

Removing final modifier just hides the problem, Parent0 still have methods overriding Parent1, which is unnecessary.