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fuchsia / third_party / github.com / rust-lang / rust / bd33b83cfdbac9bffa3b04aaef95ec97827909a9
commitbd33b83cfdbac9bffa3b04aaef95ec97827909a9[log] [tgz]
authorbors <bors@rust-lang.org>Mon Jan 05 14:55:14 2026 +0000
committerbors <bors@rust-lang.org>Mon Jan 05 14:55:14 2026 +0000
tree3d70d2d287c4af36fff93ef5d8a93e4dbf890971
parentb7bcaa5c715ed07af2d74dac7ddb8786abeb4299 [diff]
parentbd79ea1b743cccde61ffda92ba4f41abdfab515c [diff]
Auto merge of #149784 - fereidani:retain_mut, r=joboet

Improve alloc `Vec::retain_mut` performance

Hi,

While reading the rustc source code, I noticed it uses `smallvec` and `thin-vec` in many places. I started reviewing those crates, optimized their `retain_mut` implementation, and then realized they were using the exact same algorithm as `alloc::vec::Vec` with less unsafe  So now I’m back here with a PR for the standard library 😂.

In my benchmarks, this version is noticeably faster when `retain_mut` actually removes elements (thanks to fewer pointer operations, it just advances `write_index`), while performing identically to the current implementation when nothing is removed.

Let’s see if bors likes this change or not.
tree: 3d70d2d287c4af36fff93ef5d8a93e4dbf890971
  1. .github/
  2. compiler/
  3. library/
  4. LICENSES/
  5. src/
  6. tests/
  7. .clang-format
  8. .editorconfig
  9. .git-blame-ignore-revs
  10. .gitattributes
  11. .gitignore
  12. .gitmodules
  13. .ignore
  14. .mailmap
  15. bootstrap.example.toml
  16. Cargo.lock
  17. Cargo.toml
  18. CODE_OF_CONDUCT.md
  19. configure
  20. CONTRIBUTING.md
  21. COPYRIGHT
  22. INSTALL.md
  23. LICENSE-APACHE
  24. license-metadata.json
  25. LICENSE-MIT
  26. package.json
  27. README.md
  28. RELEASES.md
  29. REUSE.toml
  30. rust-bors.toml
  31. rustfmt.toml
  32. triagebot.toml
  33. typos.toml
  34. x
  35. x.ps1
  36. x.py
  37. yarn.lock
README.md

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