[derive] Avoid ambiguities referring to associated items

[joshlf]

Release 0.8.34.

Closes #2915

---

• 　 [derive] In tests, assert hygiene of output #2918
• 👉 [derive] Avoid ambiguities referring to associated items #2917

Latest Update: v4 — Compare vs v3

📚 Full Patch History

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

Version	v3	v2	v1	Base
v4	vs v3	vs v2	vs v1	vs Base
v3		vs v2	vs v1	vs Base
v2			vs v1	vs Base
v1				vs Base

[gemini-code-assist]

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 introduces version 0.8.34 for the zerocopy and zerocopy-derive crates. The primary change addresses a critical ambiguity issue within the procedural macros, specifically when associated types in derived trait implementations could conflict with user-defined types or generic parameters sharing the same names. The fix involves explicitly qualifying these associated types in the generated code, ensuring correct compilation and preventing name collisions. A new test case has been added to validate this fix, and the generated code now includes a deny lint to enforce this behavior going forward.

Highlights

• Version Update: The zerocopy and zerocopy-derive crates have been updated to version 0.8.34.
• Ambiguity Resolution: Fixed an issue where associated items (like Type and PointerMetadata) in derived trait implementations could be ambiguous, especially when user types or generic parameters shared those names.
• Explicit Trait Qualification: The generated code for KnownLayout and HasField traits now explicitly qualifies associated types (e.g., <Self as Trait>::AssociatedType) to prevent name collisions.
• New Test Case: A new test file (issue_2915.rs) was added to specifically reproduce and verify the fix for the associated item ambiguity, covering various collision scenarios.
• Compiler Enforcement: The generated code now includes #[deny(ambiguous_associated_items)] to ensure that such ambiguities are caught at compile time, preventing regressions.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

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. ↩

[gemini-code-assist]

Code Review

This pull request updates the crate versions from 0.8.33 to 0.8.34 across Cargo.toml files for both zerocopy and zerocopy-derive. The core changes involve explicitly qualifying associated types like PointerMetadata and Type within the known_layout.rs and try_from_bytes.rs derive implementations. This addresses potential ambiguities when Self or generic parameters have conflicting associated items, improving the robustness of the generated code. Additionally, #[deny(ambiguous_associated_items)] has been added to generated code blocks and test output files, which is a great step to prevent future ambiguities. A new test file, issue_2915.rs, has been added to specifically test and confirm the fix for the reported ambiguity issue, which is excellent for regression prevention.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.90%. Comparing base (dce155c) to head (175a244).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2917   +/-   ##
=======================================
  Coverage   91.90%   91.90%           
=======================================
  Files          20       20           
  Lines        5883     5883           
=======================================
  Hits         5407     5407           
  Misses        476      476           

☔ 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]

CI is failing, I believe due to: nextest-rs/nextest#2990