[derive] Unify handling of #[allow] attributes

[joshlf]

Introduce a single const_block utility function which generates a
const _: () = { ... }; block annotated with all relevant
#[allow(...)] attributes. Remove #[allow(...)] attributes from most
other places in the codebase.

Add #[allow(non_ascii_idents)] to this list.

Makes progress on #2880

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• 👉 [derive] Unify handling of #[allow] attributes #2882

Latest Update: v9 — Compare vs v8

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[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 refactors how #[allow] attributes are managed within the zerocopy-derive crate. By introducing a single const_block utility, the PR centralizes lint suppression, removing redundant #[allow] directives from various locations. This consolidation enhances code clarity and maintainability, ensuring that all necessary lint suppressions are applied consistently and in one place, including a new allowance for non_ascii_idents to resolve a specific issue.

Highlights

• Centralized Lint Suppression: A new utility function, const_block, has been introduced to centralize the application of #[allow(...)] attributes. This function generates a const _: () = { ... }; block that encapsulates all relevant lint suppressions.
• Reduced Redundancy: Numerous #[allow(...)] attributes that were previously scattered throughout the codebase have been removed, as their functionality is now handled by the new const_block utility.
• New Lint Added: The #[allow(non_ascii_idents)] attribute has been added to the centralized list of lints suppressed by the const_block function, addressing issue Zerocopy 0.8.32 breaks combined with deny(non_ascii_idents) #2880.
• Improved Macro Hygiene: The change improves macro hygiene by consolidating lint suppressions, making the generated code cleaner and easier to maintain.

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[gemini-code-assist]

Code Review

This pull request is a solid refactoring that unifies the handling of #[allow] attributes on generated code by introducing a const_block helper function. This improves maintainability by centralizing lint suppression. The changes are consistent and well-executed. I've identified a couple of places where this new pattern could be applied to further improve consistency, specifically in the derive implementations for Hash and Eq.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.90%. Comparing base (f7748fb) to head (ea01b6d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2882   +/-   ##
=======================================
  Coverage   91.90%   91.90%           
=======================================
  Files          20       20           
  Lines        5878     5878           
=======================================
  Hits         5402     5402           
  Misses        476      476           

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[kristof-mattei]

Sorry to jump in. I noticed this was approved, but validating it against #2880 still gives an error.

Threw the code in a repo to make it easier to test: https://github.com/kristof-mattei/zerocopy-non-ascii-error

[joshlf]

Updated this so it won't close #2880 when merged. It's still worth merging since it cleans up our handling of #[allow(...)] attributes.