Implement normalize_lexically

[ChrisDenton]

Implements #134694

This is, I think, the most straightforward implementation I could do, which will hopefully more easily allow experimentation if we decide to change the design here.

[rustbot]

r? @workingjubilee

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[workingjubilee]

Shouldn't Component::RootDir be unreachable? (We just checked it and skipped it.)

[workingjubilee]

This is also a "should never happen" case, isn't it?

[bors]

☔ The latest upstream changes (presumably #136533) made this pull request unmergeable. Please resolve the merge conflicts.

[workingjubilee]

Hmm. This wasn't supposed to get frozen on those two questions, so I'm just going to rebase this and approve it. If I think we maybe should call unreachable!() instead of returning I can just PR that.

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] run_time_detect test:true 0.054
error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:1996:21
     |
1996 |     check("..", Err(NormalizeError));
     |                     ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:1997:24
     |
1997 |     check("../..", Err(NormalizeError));
     |                        ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:1998:26
     |
1998 |     check("a/../..", Err(NormalizeError));
     |                          ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:1999:28
     |
1999 |     check("a/../../b", Err(NormalizeError));
     |                            ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2000:30
     |
2000 |     check("a/../../b/c", Err(NormalizeError));
     |                              ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2001:31
     |
2001 |     check("a/../b/../..", Err(NormalizeError));
     |                               ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2011:29
     |
2011 |         check(r"C:\..", Err(NormalizeError));
     |                             ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2012:34
     |
2012 |         check(r"C:\a\..\..", Err(NormalizeError));
     |                                  ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2014:28
     |
2014 |         check(r"C:..", Err(NormalizeError));
     |                            ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2015:33
     |
2015 |         check(r"C:a\..\..", Err(NormalizeError));
     |                                 ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2017:41
     |
2017 |         check(r"\\server\share\..", Err(NormalizeError));
     |                                         ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2018:46
     |
2018 |         check(r"\\server\share\a\..\..", Err(NormalizeError));
     |                                              ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2020:27
     |
2020 |         check(r"\..", Err(NormalizeError));
     |                           ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2021:32
     |
2021 |         check(r"\a\..\..", Err(NormalizeError));
     |                                ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2023:47
     |
2023 |         check(r"\\?\UNC\server\share\..", Err(NormalizeError));
     |                                               ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

error[E0423]: expected value, found struct `NormalizeError`
    --> library/std/tests/path.rs:2024:52
     |
2024 |         check(r"\\?\UNC\server\share\a\..\..", Err(NormalizeError));
     |                                                    ^^^^^^^^^^^^^^ constructor is not visible here due to private fields

[RUSTC-TIMING] minmax_stability_issue_23687 test:true 0.064
[RUSTC-TIMING] win_delete_self test:true 0.035
[RUSTC-TIMING] stdbenches test:true 0.139
error[E0658]: use of unstable library feature `normalize_lexically`
    --> library/std/tests/path.rs:1983:39
     |
1983 |     fn check(a: &str, b: Result<&str, NormalizeError>) {
     |                                       ^^^^^^^^^^^^^^
     |
     = note: see issue #134694 <https://github.com/rust-lang/rust/issues/134694> for more information
     = help: add `#![feature(normalize_lexically)]` to the crate attributes to enable
     = note: this compiler was built on 2025-04-01; consider upgrading it if it is out of date
---
[RUSTC-TIMING] builtin_clone test:true 0.051
error[E0658]: use of unstable library feature `normalize_lexically`
    --> library/std/tests/path.rs:1984:33
     |
1984 |         assert_eq!(Path::new(a).normalize_lexically(), b.map(PathBuf::from));
     |                                 ^^^^^^^^^^^^^^^^^^^
     |
     = note: see issue #134694 <https://github.com/rust-lang/rust/issues/134694> for more information
     = help: add `#![feature(normalize_lexically)]` to the crate attributes to enable
     = note: this compiler was built on 2025-04-01; consider upgrading it if it is out of date

[workingjubilee]

ugh, the move of the tests breaks them because they relied on a struct expr