Sandbox::https://github.com/cpplint/cpplint/pull/478

Csq57 · 2026-10-25T07:17:10Z

Summary

Replace three deprecated os.path.commonprefix() calls with path-aware os.path.commonpath() logic.
Handle cross-drive ValueError on Windows, add five regression tests for path boundaries and Git/Hg/SVN layouts, and update CHANGELOG.rst.

Why

Following the Python 3.15 verification requested in #445, the current develop revision produces four CLI expected-output failures because os.path.commonprefix() emits a new DeprecationWarning. This patch removes the deprecated calls without suppressing warnings.

Verification

OS	Unpatched Python 3.15.1	Patched Python 3.15.1
Ubuntu	227 passed, 4 failed	236 passed
Windows	227 passed, 4 failed	236 passed
macOS	227 passed, 4 failed	236 passed

Comparison with pytest 9.1.1: https://github.com/Csq57/ai-python-repository-stabilization-case-study/actions/runs/40162126587

Additionally, the patched code passed 9/9 jobs across Ubuntu, Windows, and macOS with Python 3.13, 3.14, and 3.15.1. Coverage was 96.67% (95% required), and Pylint, Mypy, Ruff, and all pre-commit checks passed.

Full quality evidence: https://github.com/Csq57/ai-python-repository-stabilization-case-study/actions/runs/40160493672

The unpatched four-test failures remain visible in the comparison logs. The earlier Python 3.14 issue in #445 also requires an official release, so this PR does not claim to close that issue.

This contribution was prepared with AI assistance and verified using recorded CI executions. I welcome maintainer feedback.

Summary by CodeRabbit

Bug Fixes
- Corrected repository path checks to distinguish true parent directories from similarly prefixed paths. Paths on different Windows drives are also handled safely.
- Improved repository-relative path reporting for Git, Mercurial, and SVN checkouts, including nested SVN metadata and paths with normalized parent segments.

Handle Python 3.15 os.path.commonprefix deprecation without masking warnings, and add Git/Hg/SVN and path-boundary regression coverage. Co-developed with AI assistance; manually verifiable CI results: https://github.com/Csq57/ai-python-repository-stabilization-case-study/actions/runs/40160493672 https://github.com/Csq57/ai-python-repository-stabilization-case-study/actions/runs/40162126587

coderabbitai · 2026-10-25T07:17:25Z

No actionable comments were generated in the recent review.

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Reviewing files that changed from the base of the PR and between a7d5245 and 4f1aa39.

Files selected for processing: 2

cpplint.py
cpplint_unittest.py

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Walkthrough

Path containment and repository-relative path handling now use path-aware comparisons instead of character-based prefixes. Tests cover path relationships and Git, Mercurial, and Subversion metadata.

Changes: Path-aware checks

Layer / File(s)	Summary
Repository-relative paths `cpplint.py`, `cpplint_unittest.py`, `CHANGELOG.rst`	`FileInfo.RepositoryName` uses path-aware relative-path calculations. Tests cover Git, Mercurial, and Subversion metadata, including nested SVN metadata and POSIX double-slash paths. The changelog records the replacement.
Parent-or-same path checks `cpplint.py`, `cpplint_unittest.py`	`_IsParentOrSame` uses path-component comparisons. Tests cover equal paths, descendants, ancestors, sibling prefixes, normalized paths, Windows cross-drive paths, and POSIX double-slash paths.

Priority: Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related issues

cpplint/cpplint issue 445: This change removes three os.path.commonprefix() sources of deprecation warnings. It does not change the separate codecs.open() warning.

Merge Risk: Minimal · up to 4f1aa

No merge-blocking issue is established; the change is ready for normal merge checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title "fix: replace deprecated os.path.commonprefix() for Python 3.15" matches the main change. The PR replaces three deprecated os.path.commonprefix() calls with path-aware os.path.commonpath() l…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title "fix: replace deprecated os.path.commonprefix() for Python 3.15" matches the main change. The PR replaces three deprecated os.path.commonprefix() calls with path-aware os.path.commonpath() logic, and the changelog entry and cpplint.py changes reflect this. The title does not name the secondary changes (Windows cross-drive handling, repository-relative paths via pathlib, and regression tests), but it does not need to cover every detail.

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Actionable comments posted: 2

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Inline comments:
Review comments at @cpplint.py:
- Line 7985: Update _IsParentOrSame to compare normalized path components rather
than requiring commonpath() to preserve the parent’s spelling, so a parent
beginning with double slashes correctly matches its descendants.
- Line 1791: Update the repository-name calculation in both branches to use
os.path.relpath with fullname and root_dir after locating the repository root,
rather than slicing fullname using the normalized commonpath prefix; this keeps
names relative for paths with double leading slashes.

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Reviewing files that changed from the base of the PR and between 926bf4b and a7d5245.

Files selected for processing: 3

CHANGELOG.rst
cpplint.py
cpplint_unittest.py

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cclauss

Nice.

Copilot

🟡 Changes recommended

Verified double-leading-slash POSIX path regressions affect repository-relative names and directory exclusions.

2 open issues

What changed in this PR

This PR replaces deprecated path-prefix calls to address Python 3.15 warnings while preserving cpplint’s repository detection and file-exclusion behavior.

Changes:

Replace three commonprefix() calls with commonpath(), including cross-drive error handling for exclusions.
Add regression tests for path boundaries and Git, Hg, and SVN layouts.
Document the compatibility change in the changelog.

File	Description
cpplint.py	Updates repository-path and parent-directory checks.
cpplint_unittest.py	Adds path-boundary and repository-layout regression tests.
CHANGELOG.rst	Records the deprecated API replacement.

_{Review effort: Balanced}

Address the two verified CodeRabbit and Copilot review findings: use pathlib.PurePath.relative_to() for VCS-relative path names, avoiding length-based slices and os.path.abspath monkeypatch leakage; compare normalized commonpath components for parent checks. Add POSIX double-slash regression coverage for exclusions and Git/Mercurial/SVN layouts, with docstrings and Ruff formatting. Verified in 12 independent Ubuntu/Windows/macOS × Python 3.10, 3.13, 3.14 and 3.15.1 jobs; coverage 96.66%, Pylint, Mypy and pre-commit passed: https://github.com/Csq57/ai-python-repository-stabilization-case-study/actions/runs/40308359839

Copilot

🟢 Approval recommended

No active review issues are reported for the changes replacing deprecated path-handling APIs.

No open issues 🎉

2 resolved since last review

_{Review effort: Balanced}

coderabbitai Bot reviewed Oct 25, 2026

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Comment thread cpplint.py Resolved

Comment thread cpplint.py Resolved

cclauss approved these changes Oct 26, 2026

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cclauss requested review from aaronliu0130 and a balanced review from Copilot October 26, 2026 05:04

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Comment thread cpplint.py Resolved

Comment thread cpplint.py Resolved

cclauss self-requested a review October 26, 2026 05:12

cclauss requested a balanced review from Copilot October 28, 2026 18:21

Copilot started reviewing on behalf of cclauss October 28, 2026 18:21

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Skytuhua mentioned this pull request Oct 29, 2026

Detect missing control-keyword spacing at the start of a line #479

Open

cclauss merged commit 6501a49 into cpplint:develop Oct 29, 2026
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fix: replace deprecated os.path.commonprefix() for Python 3.15 - #478

fix: replace deprecated os.path.commonprefix() for Python 3.15#478
cclauss merged 2 commits into
cpplint:developfrom
Csq57:fix/python315-commonpath-deprecation

Csq57 commented Oct 25, 2026 •

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Csq57 commented Oct 25, 2026 •

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