Child class overrides lambda in parent class

This was initially reported in the gradle-retrolambda project, but the problem appears to come from this project.

Copying the report here:

---

public abstract class ParentActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(getContentView());
        findViewById(R.id.button_parent).setOnClickListener(view -> Toast.makeText(this, "Parent onClick", Toast.LENGTH_LONG).show());
    }

    public abstract int getContentView();
}

public class MainActivity extends ParentActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        findViewById(R.id.button_child).setOnClickListener(view -> Toast.makeText(this, "Child onClick", Toast.LENGTH_LONG).show());
    }

    @Override
    public int getContentView() {
        return R.layout.activity_main;
    }
}

Clicking on button_parent shows a Toast with “Child onClick”

test app: https://github.com/cpalasanu/RetrolambdaTest

---

Using the cfr decompiler, we see that the child activity class has a method that overrides the parent activity class:

Parent:

/*
 * Decompiled with CFR 0_118.
 * 
 * Could not load the following classes:
 *  android.content.Context
 *  android.os.Bundle
 *  android.support.annotation.Nullable
 *  android.support.v7.app.AppCompatActivity
 *  android.view.View
 *  android.view.View$OnClickListener
 *  android.widget.Toast
 */
package com.orange.retrolambdatest;

import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;
import com.orange.retrolambdatest.ParentActivity$$Lambda$1;

public abstract class ParentActivity
extends AppCompatActivity {
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(this.getContentView());
        this.findViewById(2131427412).setOnClickListener(ParentActivity$$Lambda$1.lambdaFactory$(this));
    }

    public abstract int getContentView();

    /* synthetic */ void lambda$onCreate$0(View view) {
        Toast.makeText((Context)this, (CharSequence)"Parent onClick", (int)1).show();
    }
}

Child:

/*
 * Decompiled with CFR 0_118.
 * 
 * Could not load the following classes:
 *  android.content.Context
 *  android.os.Bundle
 *  android.view.View
 *  android.view.View$OnClickListener
 *  android.widget.Toast
 */
package com.orange.retrolambdatest;

import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
import com.orange.retrolambdatest.MainActivity$$Lambda$1;
import com.orange.retrolambdatest.ParentActivity;

public class MainActivity
extends ParentActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.findViewById(2131427413).setOnClickListener(MainActivity$$Lambda$1.lambdaFactory$(this));
    }

    @Override
    public int getContentView() {
        return 2130968602;
    }

    @Override
    /* synthetic */ void lambda$onCreate$0(View view) {
        Toast.makeText((Context)this, (CharSequence)"Child onClick", (int)1).show();
    }
}

Both parent and child have the same method lambda$onCreate$0(View view)

---

I did some tests building the retrolambda project locally. It appears the bug appears in this commit: https://github.com/orfjackal/retrolambda/commit/bf932457e45817cdee07f34c8c2059db44848e03 (between releases 2.2.0 and 2.3.0) The PR for that commit: https://github.com/orfjackal/retrolambda/pull/86

I have not done any investigation to understand what part of that commit introduces the bug.

[luontola]

I’ve made a fix for this which converts the private instance methods into package-private static methods. Please try it out. I’ll release a new version soon.

[luontola]

The fix to this has been released in Retrolambda 2.5.0