Skip to content

[pointer] Add project_ptr_inner! helper #2854

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Open
joshlf wants to merge 1 commit into
base: main
Choose a base branch
from
Open

[pointer] Add project_ptr_inner! helper #2854

joshlf wants to merge 1 commit into from
+334 −72

Conversation

@joshlf
Copy link
Member

@joshlf joshlf commented Dec 17, 2025 •
edited
Loading

Latest Update: v10 — Compare vs v9

📚 Full Patch History

Links show the diff between the row version and the column version.

Version Base v1 v2 v3 v4 v5 v6 v7 v8 v9
v10 Base v1 v2 v3 v4 v5 v6 v7 v8 v9
v9 Base v1 v2 v3 v4 v5 v6 v7 v8
v8 Base v1 v2 v3 v4 v5 v6 v7
v7 Base v1 v2 v3 v4 v5 v6
v6 Base v1 v2 v3 v4 v5
v5 Base v1 v2 v3 v4
v4 Base v1 v2 v3
v3 Base v1 v2
v2 Base v1
v1 Base

@gemini-code-assist
Copy link
Contributor

gemini-code-assist bot commented Dec 17, 2025

Summary of Changes

Hello @joshlf, 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!

This pull request enhances the pointer module by introducing a new helper macro, project_ptr_inner!. This macro provides a safe and controlled way to project an existing PtrInner to a specific field within its underlying struct or union, with the added capability of performing type transmutes. The change aims to facilitate more flexible and safe low-level pointer operations while adhering to strict provenance and memory safety rules, backed by thorough testing.

Highlights

  • New project_ptr_inner! Macro: Introduces a new #[macro_export] macro designed to project a PtrInner to a specific field of its referent type. This macro allows for safe low-level pointer manipulation, enabling access to struct or union fields while adhering to strict safety requirements.
  • Optional Type Transmutation: The project_ptr_inner! macro supports an optional type annotation for the target field, allowing for type transmutes. This feature is carefully designed with safety requirements to ensure that the transmute preserves or shrinks the size of the referent, maintaining memory safety and correct provenance.
  • Comprehensive Test Coverage: Extensive unit tests have been added to validate the project_ptr_inner! macro's functionality across various scenarios, including sized fields, dynamically sized types (DSTs), zero-sized types (ZSTs), and projections within unions, ensuring robustness and correctness of the implementation.
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 by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

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 pull request 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 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. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

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.

Footnotes

  1. 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. ↩

@joshlf joshlf requested a review from jswrenn December 17, 2025 20:42
@joshlf joshlf mentioned this pull request Dec 17, 2025
Open
gemini-code-assist[bot]
gemini-code-assist bot reviewed Dec 17, 2025
View reviewed changes
Copy link
Contributor

@gemini-code-assist gemini-code-assist bot left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Code Review

This pull request introduces a project_ptr_inner! macro for projecting PtrInner to a field, along with a comprehensive test suite. The macro implementation appears sound, but I've found a few issues. There are a couple of TODO comments that should be FIXMEs according to the repository's style guide. More importantly, one of the new tests appears to rely on a pointer cast (*mut [u8] to *mut [()]) that is documented as a compile-time error in Rust, which could lead to undefined behavior or compiler-specific dependencies.

@joshlf joshlf force-pushed the G57b42ad4ff767a765f9b4ac149aa1c19d3796711 branch from 8a4e49b to 09d0afd Compare December 17, 2025 20:48
@codecov-commenter
Copy link

codecov-commenter commented Dec 17, 2025 •
edited
Loading

Codecov Report

❌ Patch coverage is 98.93617% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.15%. Comparing base (002b97d) to head (6450ea0).

Files with missing lines Patch % Lines
src/pointer/inner.rs 98.91% 1 Missing ⚠️
Additional details and impacted files 
@@            Coverage Diff             @@
##             main    #2854      +/-   ##
==========================================
+ Coverage   92.05%   92.15%   +0.10%     
==========================================
  Files          20       20              
  Lines        5812     5905      +93     
==========================================
+ Hits         5350     5442      +92     
- Misses        462      463       +1

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

@joshlf joshlf force-pushed the G57b42ad4ff767a765f9b4ac149aa1c19d3796711 branch 7 times, most recently from 206be9f to a48c662 Compare December 17, 2025 23:50
@joshlf
[pointer] Add project_ptr_inner! helper
6450ea0 
gherrit-pr-id: G57b42ad4ff767a765f9b4ac149aa1c19d3796711
@joshlf joshlf force-pushed the G57b42ad4ff767a765f9b4ac149aa1c19d3796711 branch from a48c662 to 6450ea0 Compare December 18, 2025 18:10
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@jswrenn jswrenn Awaiting requested review from jswrenn

1 more reviewer

@gemini-code-assist gemini-code-assist[bot] gemini-code-assist[bot] left review comments

Reviewers whose approvals may not affect merge requirements

At least 1 approving review is required to merge this pull request.

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@joshlf @codecov-commenter