UPSTREAM PR #2458: fix(tree): std::path::Component has infallible conversion to &[u8]

[loci-dev]

Note

Source pull request: GitoxideLabs/gitoxide#2458

The checks/conversions done in the _by_path methods in Tree and TreeRefIter are unnecessary, so this PR removes them in favor of using OsStr::as_encoded_bytes().

Since as_os_str().as_encoded_bytes() takes &self and (as far as I know) no platforms use internal mutability on OsStr, the underlying value must already have the form we want. The only thing that os_str_into_bstr does for us is validate that the byte string contains valid UTF-8. However, the only thing these BStrs are used for is comparison to other BStrs. Whether either of them is valid UTF-8 does not impact the function in any way (as string conversion errors are silently ignored), so we can simply skip the whole validation step and get ever-so-slightly-cheaper lookups by path.

Please let me know if this change is useful/welcome or not, I can imagine that there may be some case I have not thought of that breaks from this change.

[loci-review]

Overview

Analysis of 31,034 functions (1,742 modified, 4,771 new, 4,774 removed) across two binaries shows negligible performance impact from path conversion simplification commits.

Binaries analyzed:

• target.aarch64-unknown-linux-gnu.release.gix: +0.05% power consumption (+401 nJ)
• target.aarch64-unknown-linux-gnu.release.ein: -0.003% power consumption (-8 nJ)

Commits: Two focused changes simplified std::path::Component to &[u8] conversion (making it infallible) and removed the gix-path dependency from gix-object.

Function Analysis

Most performance variations are compiler-driven code generation differences rather than algorithmic changes from the source modifications:

Performance-critical improvements:

• gix_diff::rewrites::Tracker::try_push_change: -28% response time (-159ns) — eliminated exception handling overhead in rename detection pipeline

Performance-critical regressions:

• gix_fs::Stack::make_relative_path_current: +21% response time (+2,619ns) — doubled next_match() calls from 2 to 4, affects status operations and worktree traversal
• gix_index::extension::Tree::verify_recursive: +54% response time (+1,196ns) — duplicated operations and added memory allocations

Non-critical changes:

• Standard library thread initialization: +157% response time (+1,199ns)
• Debug formatting implementations: +43% to +15,659% (only affects error display/logging)
• Commit graph serialization: +91% response time (+57.8μs, infrequent CLI output)
• Channel operations: Mixed results (+8% in gix, -4% in ein)
• Shell completion: -48% response time (-22.9μs improvement)

Other analyzed functions showed negligible changes or compiler optimization variations in external dependencies.

Source code relationship: The path conversion changes in gix-object do not directly affect most regressed functions. Performance variations stem from compiler optimization differences between builds rather than the intentional source modifications, which successfully simplified code without algorithmic regressions.

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