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8a7ca936e6
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.
92 lines
2.3 KiB
Rust
92 lines
2.3 KiB
Rust
#![feature(allocator_api)]
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#![feature(alloc_layout_extra)]
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#![feature(assert_matches)]
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#![feature(btree_drain_filter)]
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#![feature(cow_is_borrowed)]
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#![feature(const_convert)]
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#![feature(const_cow_is_borrowed)]
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#![feature(const_heap)]
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#![feature(const_mut_refs)]
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#![feature(const_slice_from_raw_parts_mut)]
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#![feature(const_ptr_write)]
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#![feature(const_try)]
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#![feature(core_intrinsics)]
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#![feature(drain_filter)]
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#![feature(exact_size_is_empty)]
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#![feature(linked_list_cursors)]
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#![feature(map_try_insert)]
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#![feature(new_uninit)]
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#![feature(pattern)]
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#![feature(trusted_len)]
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#![feature(try_reserve_kind)]
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#![feature(unboxed_closures)]
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#![feature(associated_type_bounds)]
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#![feature(binary_heap_into_iter_sorted)]
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#![feature(binary_heap_drain_sorted)]
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#![feature(slice_ptr_get)]
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#![feature(binary_heap_retain)]
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#![feature(binary_heap_as_slice)]
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#![feature(inplace_iteration)]
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#![feature(iter_advance_by)]
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#![feature(iter_next_chunk)]
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#![feature(round_char_boundary)]
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#![feature(slice_group_by)]
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#![feature(slice_partition_dedup)]
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#![feature(string_remove_matches)]
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#![feature(const_btree_len)]
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#![feature(const_default_impls)]
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#![feature(const_trait_impl)]
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#![feature(const_str_from_utf8)]
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#![feature(panic_update_hook)]
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#![feature(pointer_is_aligned)]
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#![feature(slice_flatten)]
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#![feature(thin_box)]
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#![feature(strict_provenance)]
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#![feature(drain_keep_rest)]
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#![deny(fuzzy_provenance_casts)]
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#![deny(unsafe_op_in_unsafe_fn)]
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use std::collections::hash_map::DefaultHasher;
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use std::hash::{Hash, Hasher};
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mod arc;
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mod autotraits;
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mod borrow;
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mod boxed;
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mod btree_set_hash;
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mod c_str;
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mod const_fns;
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mod cow_str;
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mod fmt;
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mod heap;
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mod linked_list;
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mod rc;
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mod slice;
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mod str;
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mod string;
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mod thin_box;
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mod vec;
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mod vec_deque;
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fn hash<T: Hash>(t: &T) -> u64 {
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let mut s = DefaultHasher::new();
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t.hash(&mut s);
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s.finish()
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}
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// FIXME: Instantiated functions with i128 in the signature is not supported in Emscripten.
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// See https://github.com/kripken/emscripten-fastcomp/issues/169
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#[cfg(not(target_os = "emscripten"))]
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#[test]
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fn test_boxed_hasher() {
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let ordinary_hash = hash(&5u32);
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let mut hasher_1 = Box::new(DefaultHasher::new());
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5u32.hash(&mut hasher_1);
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assert_eq!(ordinary_hash, hasher_1.finish());
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let mut hasher_2 = Box::new(DefaultHasher::new()) as Box<dyn Hasher>;
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5u32.hash(&mut hasher_2);
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assert_eq!(ordinary_hash, hasher_2.finish());
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}
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