Hello @katafrakt, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

Hello team, gemini-code-assist here to provide a summary of this pull request. This PR addresses a regression introduced in commit 6c72f8b378fc8743ec1775b3e2d7dd507ec2b394 that affected the behavior of the extended callback when using Object#extend. Previously, the extended callback was incorrectly being searched for and called on the singleton class of the object being extended, rather than on the module being used for extension. This PR corrects the logic in mrb_obj_extend to properly find and invoke the extended method on the module itself, passing the object being extended as the argument, which aligns with standard Ruby behavior. A new test case has also been added to verify this corrected behavior.

Highlights

Bug Fix: Fixes a regression where the extended callback was incorrectly handled during Object#extend.
Callback Logic Correction: Ensures the extended method is looked up and called on the module being extended, not the object's singleton class.
New Test Case: Adds a dedicated test to verify the correct invocation and behavior of the extended callback.

Changelog

src/class.c
- Modified mrb_obj_extend (lines 1684-1685) to check for the extended method on the module (mod) instead of the object's singleton class (cc).
- Modified mrb_obj_extend (lines 1684-1685) to call the extended method on the module (mod) and pass the object being extended (obj) as the argument.
test/t/class.rb
- Added a new test case (assert('module with extended callback')) starting at line 481.
- The new test defines a module with a self.extended method and a class that tracks if it was extended, verifying the callback is triggered correctly.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist is currently in preview and may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments to provide feedback.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

A module extends,
A callback sends,
The object's state bends.
Fix the call, make amends.

Footnotes

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩