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Partial stabilization of `once_cell` This PR aims to stabilize a portion of the `once_cell` feature: - `core::cell::OnceCell` - `std::cell::OnceCell` (re-export of the above) - `std::sync::OnceLock` This will leave `LazyCell` and `LazyLock` unstabilized, which have been moved to the `lazy_cell` feature flag. Tracking issue: https://github.com/rust-lang/rust/issues/74465 (does not fully close, but it may make sense to move to a new issue) Future steps for separate PRs: - ~~Add `#[inline]` to many methods~~ #105651 - Update cranelift usage of the `once_cell` crate - Update rust-analyzer usage of the `once_cell` crate - Update error messages discussing once_cell ## To be stabilized API summary ```rust // core::cell (in core/cell/once.rs) pub struct OnceCell<T> { .. } impl<T> OnceCell<T> { pub const fn new() -> OnceCell<T>; pub fn get(&self) -> Option<&T>; pub fn get_mut(&mut self) -> Option<&mut T>; pub fn set(&self, value: T) -> Result<(), T>; pub fn get_or_init<F>(&self, f: F) -> &T where F: FnOnce() -> T; pub fn into_inner(self) -> Option<T>; pub fn take(&mut self) -> Option<T>; } impl<T: Clone> Clone for OnceCell<T>; impl<T: Debug> Debug for OnceCell<T> impl<T> Default for OnceCell<T>; impl<T> From<T> for OnceCell<T>; impl<T: PartialEq> PartialEq for OnceCell<T>; impl<T: Eq> Eq for OnceCell<T>; ``` ```rust // std::sync (in std/sync/once_lock.rs) impl<T> OnceLock<T> { pub const fn new() -> OnceLock<T>; pub fn get(&self) -> Option<&T>; pub fn get_mut(&mut self) -> Option<&mut T>; pub fn set(&self, value: T) -> Result<(), T>; pub fn get_or_init<F>(&self, f: F) -> &T where F: FnOnce() -> T; pub fn into_inner(self) -> Option<T>; pub fn take(&mut self) -> Option<T>; } impl<T: Clone> Clone for OnceLock<T>; impl<T: Debug> Debug for OnceLock<T>; impl<T> Default for OnceLock<T>; impl<#[may_dangle] T> Drop for OnceLock<T>; impl<T> From<T> for OnceLock<T>; impl<T: PartialEq> PartialEq for OnceLock<T> impl<T: Eq> Eq for OnceLock<T>; impl<T: RefUnwindSafe + UnwindSafe> RefUnwindSafe for OnceLock<T>; unsafe impl<T: Send> Send for OnceLock<T>; unsafe impl<T: Sync + Send> Sync for OnceLock<T>; impl<T: UnwindSafe> UnwindSafe for OnceLock<T>; ``` No longer planned as part of this PR, and moved to the `rust_cell_try` feature gate: ```rust impl<T> OnceCell<T> { pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E> where F: FnOnce() -> Result<T, E>; } impl<T> OnceLock<T> { pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E> where F: FnOnce() -> Result<T, E>; } ``` I am new to this process so would appreciate mentorship wherever needed. |
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| README.md | ||
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