[cargo-zerocopy] Pass RUSTDOCFLAGS

[joshlf]

Pass the same set of flags to RUSTFLAGS and RUSTDOCFLAGS. Some of
our tests - specifically src/doctests.rs - use cfgs which are set by
cargo-zerocopy, but these were previously not passed when evaluating
doc tests.

This follows up on #2960, which introduced this bug.

---

• 　  [test] Migrate from trybuild to ui-test #2986
• 　  [test] Move impl_or_verify! tests to doctests #2988
• 👉 [cargo-zerocopy] Pass RUSTDOCFLAGS #2987

Latest Update: v2 — Compare vs v1

📚 Full Patch History

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Version	v1	Base
v2	vs v1	vs Base
v1		vs Base

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Branch

git fetch origin refs/heads/G413a86267ff4384a9806de9a784407f1f5be96aa && git checkout -b pr-G413a86267ff4384a9806de9a784407f1f5be96aa FETCH_HEAD

Checkout

git fetch origin refs/heads/G413a86267ff4384a9806de9a784407f1f5be96aa && git checkout FETCH_HEAD

Cherry Pick

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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 resolves an issue where cfg attributes, set by cargo-zerocopy, were not being correctly propagated to doc tests, leading to test failures. By mirroring RUSTFLAGS to RUSTDOCFLAGS, the change ensures that doc tests are executed with the appropriate compilation flags, thereby fixing the previously introduced bug and improving the reliability of doc test execution.

Highlights

• RUSTDOCFLAGS Propagation: The cargo-zerocopy tool now explicitly passes the value of the RUSTFLAGS environment variable to RUSTDOCFLAGS when invoking cargo. This ensures that cfg attributes, which are essential for certain doc tests, are correctly applied during their evaluation.

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Changelog

• tools/cargo-zerocopy/src/main.rs
  • Added a line to set the RUSTDOCFLAGS environment variable to the same value as RUSTFLAGS when cargo-zerocopy delegates to cargo.
  • Included a comment explaining the rationale behind passing RUSTFLAGS to both RUSTFLAGS and RUSTDOCFLAGS.

Activity

• The author, joshlf, created this pull request to fix an issue related to doc tests not correctly picking up cfgs, which was a follow-up to a previous change ([cargo-zerocopy] Pass --cfg __ZEROCOPY_INTERNAL_USE_ONLY_DEV_MODE #2960).
• The PR description indicates it is part of a stacked PR series, with this PR ([cargo-zerocopy] Pass RUSTDOCFLAGS #2987) being the current focus, following [test] Migrate from trybuild to ui-test #2986 and [test] Move impl_or_verify! tests to doctests #2988.

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[gemini-code-assist]

Code Review

This pull request aims to fix an issue where configuration flags were not passed to doc tests. The change correctly identifies that RUSTDOCFLAGS needs to be set. However, the current implementation reuses the computed RUSTFLAGS value, which can lead to unintended side effects like overwriting a user's RUSTDOCFLAGS or passing invalid flags to rustdoc. I've provided a suggestion to make the flag handling more robust by separately constructing RUSTFLAGS and RUSTDOCFLAGS while preserving any existing values from the environment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.87%. Comparing base (d296c26) to head (5ed532f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2987   +/-   ##
=======================================
  Coverage   91.87%   91.87%           
=======================================
  Files          20       20           
  Lines        6057     6057           
=======================================
  Hits         5565     5565           
  Misses        492      492           

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