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Differential D12433

rust-hgpath: add `repr(transparent)` to `HgPath`
ClosedPublic

Authored by Alphare on Apr 4 2022, 11:30 AM.

Details

Reviewers
None
Group Reviewers
hg-reviewers
Commits
rHG9dcfd1d05e6e: rust-hgpath: add `repr(transparent)` to `HgPath`
rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath`
Summary

It's been stabilized a long time ago, so let's not rely on an implementation
detail now.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

Alphare created this revision.Apr 4 2022, 11:30 AM
baymax updated this revision to Diff 32767.Apr 4 2022, 2:34 PM

✅ refresh by Heptapod after a successful CI run (🐙 💚)
⚠ This patch is intended for stable ⚠

Alphare added a commit: rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath`.Apr 4 2022, 4:06 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath` (authored by Alphare). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mrust/hg-core/src/utils/hg_path.rs (9 lines)

Diff 32773

rust/hg-core/src/utils/hg_path.rs

/// operation. /// operation.
/// ///
/// This allows us to be encoding-transparent as much as possible, until really /// This allows us to be encoding-transparent as much as possible, until really
/// needed; `HgPath` can be transformed into a platform-specific path (`OsStr` /// needed; `HgPath` can be transformed into a platform-specific path (`OsStr`
/// or `Path`) whenever more complex operations are needed: /// or `Path`) whenever more complex operations are needed:
/// On Unix, it's just byte-to-byte conversion. On Windows, it has to be /// On Unix, it's just byte-to-byte conversion. On Windows, it has to be
/// decoded from MBCS to WTF-8. If WindowsUTF8Plan is implemented, the source /// decoded from MBCS to WTF-8. If WindowsUTF8Plan is implemented, the source
/// character encoding will be determined on a per-repository basis. /// character encoding will be determined on a per-repository basis.
//
// FIXME: (adapted from a comment in the stdlib)
// `HgPath::new()` current implementation relies on `Slice` being
// layout-compatible with `[u8]`.
// When attribute privacy is implemented, `Slice` should be annotated as
// `#[repr(transparent)]`.
// Anyway, `Slice` representation and layout are considered implementation
// detail, are not documented and must not be relied upon.
#[derive(Eq, Ord, PartialEq, PartialOrd, Hash)] #[derive(Eq, Ord, PartialEq, PartialOrd, Hash)]
#[repr(transparent)]
pub struct HgPath { pub struct HgPath {
inner: [u8], inner: [u8],
} }
impl HgPath { impl HgPath {
pub fn new<S: AsRef<[u8]> + ?Sized>(s: &S) -> &Self { pub fn new<S: AsRef<[u8]> + ?Sized>(s: &S) -> &Self {
unsafe { &*(s.as_ref() as *const [u8] as *const Self) } unsafe { &*(s.as_ref() as *const [u8] as *const Self) }
} }