feat(clang-tidy): add --fix opt-in flag for auto-applying fixes in place

[Copilot]

The clang-tidy hook only reported issues; unlike clang-format it never modified files. This adds an opt-in --fix flag that passes -fix to clang-tidy.

Changes

• clang_tidy.py

  • New --fix parser argument; appends -fix to the clang-tidy invocation when set
  • Extended unsafe_parallel guard to cover -fix and -fix-errors (parallel runs risk concurrent writes to shared headers)
  • Serial path now uses clang_tidy_args + source_files instead of raw other_args, so injected flags are always forwarded

• tests/test_clang_tidy.py — three new unit tests:

  • --fix appends -fix to the command
  • --fix forces serial execution even with --jobs > 1
  • Direct -fix-errors in args also forces serial execution

• README.md — documents --fix, notes -fix-errors as a clang-tidy native alternative, and warns that parallelism is automatically disabled when either flag is active

Usage

- id: clang-tidy
  args: [--checks=.clang-tidy, --fix]

-fix-errors (for files with compiler errors) can be passed directly as a native clang-tidy flag. Both flags force serial execution automatically.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.70%. Comparing base (c1c3116) to head (218b369).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #206      +/-   ##
==========================================
+ Coverage   96.64%   96.70%   +0.05%     
==========================================
  Files           4        4              
  Lines         179      182       +3     
==========================================
+ Hits          173      176       +3     
  Misses          6        6              

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[codspeed-hq]

Merging this PR will not alter performance

✅ 63 untouched benchmarks
⏩ 13 skipped benchmarks¹

---

_{Comparing copilot/add-auto-fix-support-clang-tidy (218b369) with main (c1c3116)}

Footnotes

1. 13 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[shenxianpeng]

@copilot enable autofix_prs to pre-commit.ci by default

[Copilot]

@copilot enable autofix_prs to pre-commit.ci by default

autofix_prs: true is already present in .pre-commit-config.yaml under the ci: block, so pre-commit.ci will automatically open fix PRs by default — no change needed.