Add `Path::has_trailing_sep` and related methods #142506

clarfonthey · 2025-06-14T14:17:56Z

Tracking issue: #142503

Notable differences from ACP:

trim_trailing_sep was added to Path since it felt reasonable to ensure that the inverse operation was available.
Per suggestion of @kennytm, added push_trailing_sep and pop_trailing_sep to PathBuf in addition to set_trailing_sep.

This also updates some of the docs on various Path methods to use the term "trailing separator" instead of "trailing slash" for consistency.

rustbot · 2025-06-14T14:17:59Z

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clarfonthey · 2025-06-15T18:23:28Z

@rustbot author

rustbot · 2025-06-15T18:23:32Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

clarfonthey · 2025-06-29T17:27:39Z

Now that I know the workaround for the ./x test library/std, this should be good. But I'll wait until the tests pass (I'm only running on Linux atm) before I mark as ready.

There are a few edge cases, namely removing the trailing separator from /.

clarfonthey · 2025-06-29T22:32:30Z

@rustbot ready

bors · 2025-08-13T11:25:19Z

☔ The latest upstream changes (presumably #145334) made this pull request unmergeable. Please resolve the merge conflicts.

joboet · 2025-08-13T15:59:00Z

library/std/src/path.rs

+    /// assert_eq!(Path::new("dir/").trim_trailing_sep().as_os_str(), OsStr::new("dir"));
+    /// assert_eq!(Path::new("dir").trim_trailing_sep().as_os_str(), OsStr::new("dir"));
+    /// assert_eq!(Path::new("/").trim_trailing_sep().as_os_str(), OsStr::new("/"));
+    /// assert_eq!(Path::new("//").trim_trailing_sep().as_os_str(), OsStr::new("//"));


Is this correct? I would have thought that since // is the same as /, this would trim // to / (but feel free to correct me).

The idea here is that removing any number of /s would not affect the final path, and so, the path is left as-is. Essentially, any sequence of separators is treated as a single separator for the logic.

I could change it so that it returns / here but it felt better to be conservative: the logic is that trailing separators are removed if doing so would result in the same path without a trailing separator. Since there will always be trailing separators here, it doesn't make a difference to remove any. If your goal is "cleaning up" the path, then normalize and normalize_lexically exist instead.

Also another way to word this: x.trim_trailing_sep().as_os_str() == x.as_os_str() and x.trim_trailing_sep().has_trailing_sep() are equivalent.

(Note that the as_os_str is required since the trailing separator is ignored when comparing paths.)

This makes sense to me, but I'll ask for libs-api feedback just in case.

A bit of an aside but I'd just to note this from the POSIX spec:

If a pathname begins with two successive <slash> characters, the first component following the leading <slash> characters may be interpreted in an implementation-defined manner, although more than two leading characters shall be treated as a single character.

So the path \\ can be different from the path \ (although \\\ is the same as \), I do not know that this is used by any platform (maybe cygwin?) so in practice \\ will be the same as \ on supported platforms, as far as I'm aware.

Hmm, that is very strange. It doesn't seem to really follow from the way Rust treats paths, though, since in this case we would have to genuinely treat / and // as separate paths and we do not.

Well on the one hand the way rust treats paths already diverges from the spec by making a trialling \ essentially invisible (which has_trailing_sep and trim_trailing_sep seeks to rectify). On the other hand, as I said, I'm not sure that \\ makes any practical difference for the platforms we support seeing as they will all treat it the same as \.

Additional note: I implemented std::path::absolute to conform with the POSIX the spec but I don't feel especially strongly about that other than it's nice to have the same behaviour across platforms (including future platforms) where it's possible.

bors · 2025-09-04T06:20:24Z

☔ The latest upstream changes (presumably #146185) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2025-09-05T00:07:45Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

joboet · 2025-09-30T15:51:01Z

I take it from the libs-api meeting notes that the current behaviour is fine, therefore this seems good to go.

@bors r+

bors · 2025-09-30T15:51:04Z

📌 Commit 7ce8e28 has been approved by joboet

It is now in the queue for this repository.

Rollup of 6 pull requests Successful merges: - #142506 (Add `Path::has_trailing_sep` and related methods) - #146886 (Add repr(align(2)) to RcInner and ArcInner) - #147166 (several small `proc_macro` cleanups) - #147172 (bootstrap: build bootstrap docs with in-tree rustdoc) - #147181 (cg_llvm: Replace enum `MetadataType` with a list of `MetadataKindId` constants) - #147187 (remove unnecessary test directives) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #142506 - clarfonthey:path-trailing-sep, r=joboet Add `Path::has_trailing_sep` and related methods Implements rust-lang/libs-team#335. Tracking issue: #142503 Notable differences from ACP: * `trim_trailing_sep` was added to `Path` since it felt reasonable to ensure that the inverse operation was available. * Per suggestion of `@kennytm,` added `push_trailing_sep` and `pop_trailing_sep` to `PathBuf` in addition to `set_trailing_sep`. This also updates some of the docs on various `Path` methods to use the term "trailing separator" instead of "trailing slash" for consistency.

…oboet Add `Path::has_trailing_sep` and related methods Implements rust-lang/libs-team#335. Tracking issue: rust-lang#142503 Notable differences from ACP: * `trim_trailing_sep` was added to `Path` since it felt reasonable to ensure that the inverse operation was available. * Per suggestion of `@kennytm,` added `push_trailing_sep` and `pop_trailing_sep` to `PathBuf` in addition to `set_trailing_sep`. This also updates some of the docs on various `Path` methods to use the term "trailing separator" instead of "trailing slash" for consistency.

rustbot assigned joboet Jun 14, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 14, 2025

clarfonthey mentioned this pull request Jun 14, 2025

Tracking Issue for path_trailing_sep #142503

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