[GROOVY-8732] @CompileStatic refers to private field in parent class

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.15, 2.6.0-alpha-4, 3.0.0-alpha-3, 2.5.1
• Fix Version/s: 3.0.0-alpha-4, 2.5.2
• Component/s: Static compilation
• Assignee: Paul King
• Reporter: Lóránt Pintér
• Created: 06/Aug/18 12:26
• Updated: 14/Aug/18 08:05
• Resolved: 10/Aug/18 00:42

Description

import groovy.transform.CompileStatic

@CompileStatic
interface Thing {
    void call()
}

@CompileStatic
class ThingImpl implements Thing {
    void call() {}
}

@CompileStatic
class Parent {
    private final ThingImpl thing

    public Thing getThing() { null }
}

@CompileStatic
class Child extends Parent {
    public void doSomething() {
        thing.call()
    }
}

Compile via: groovyc Example.groovy.

The line thing.call in Child.doSomething() calls getThing(), but then ends up referring to the returned value according to the private field's type from Parent (ThingImpl) instead of the actual returned type (Thing). The private field from Parent (or its type) should not be visible to Child at all.

  public void doSomething();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokevirtual #20                 // Method Parent.getThing:()LThing;
         4: checkcast     #22                 // class ThingImpl
         7: invokevirtual #25                 // Method ThingImpl.call:()V
        10: aconst_null
        11: pop
        12: return

This is causing now problems for Gradle plugins compiled against Grade 4.9 or before trying to run on Gradle 4.9, because we've made a change to an internal type (`ProjectInternal`) that ended up being referred to via this bug in compiled and released code. See https://github.com/gradle/gradle/issues/6027

Issue Links

• links to: GitHub Pull Request #781