once_cell

• Reduce MSRV to 1.65: #277.

• Outline initialization in race: #273.
• Add OnceNonZereUsize::get_unchecked: #274.
• Add OnceBox::clone and OnceBox::with_value: #275.
• Increase MSRV to 1.70

• Remove portable_atomic from Cargo.lock if it is not, in fact, used: #267 This is a work-around for this cargo bug: https://github.com/rust-lang/cargo/issues/10801.

• Allow using race module using just portable_atomic, without critical_section and provide better error messages on targets without atomic CAS instruction, #265.

Merge pull request #260 from brodycj/propagate-critical-section-to-po…

• Use portable-atomic instead of atomic-polyfill, #251.

• MSRV is updated to 1.60.0 to take advantage of dep: syntax for cargo features, removing "implementation details" from publicly visible surface.

• Avoid unnecessary synchronization in Lazy::{force,deref}_mut(), #231.

• Make OnceRef implementation compliant with strict provenance.

• Add race::OnceRef for storing a &'a T.

• Add no_std implementation based on critical-section, #195.
• Deprecate atomic-polyfill feature (use the new critical-section instead)

• Increase minimal supported Rust version to 1.56.0.
• Implement UnwindSafe even if the std feature is disabled.

• Add extension to unsync and sync Lazy mut API:
  • force_mut
  • get_mut

• Make implementation compliant with strict provenance.
• Upgrade atomic-polyfill to 1.0

• Add Lazy::get, similar to OnceCell::get.

• Remove incorrect debug_assert.

• Add OnceCell::wait, a blocking variant of get.

• Add OnceCell::with_value to create initialized OnceCell in const context.
• Improve Clone implementation for OnceCell.
• Rewrite parking_lot version on top of parking_lot_core, for even smaller cells!

• upgrade parking_lot to 0.12.0 (note that this bumps MSRV with parking_lot feature enabled to 1.49.0).

• Added an atomic-polyfill optional dependency to compile race on platforms without atomics

• Add try_insert API -- a version of set that returns a reference.

• Improve code size when using parking_lot feature.

• Fix race::OnceBox<T> to also impl Default even if T doesn't impl Default.

• Hide the race module behind (default) race feature. Turns out that adding race by default was a breaking change on some platforms without atomics. In this release, we make the module opt-out. Technically, this is a breaking change for those who use race with no_default_features. Given that the race module itself only several days old, the breakage is deemed acceptable.

• Add Lazy::into_value
• Stabilize once_cell::race module for "first one wins" no_std-compatible initialization flavor.
• Migrate from deprecated compare_and_swap to compare_exchange.

• OnceBox API uses Box<T>. This a breaking change to unstable API.

• MSRV is increased to 1.36.0.
• document once_cell::race module.
• introduce alloc feature for OnceBox.
• fix OnceBox::set.

• add new once_cell::race module for "first one wins" no_std-compatible initialization flavor. The API is provisional, subject to change and is gated by the unstable cargo feature.

• upgrade parking_lot to 0.11.0
• make sync::OnceCell<T> pass https://doc.rust-lang.org/nomicon/dropck.html#an-escape-hatch[dropck] with parking_lot feature enabled. This fixes a (minor) semver-incompatible changed introduced in 1.4.0

• upgrade parking_lot to 0.10 (note that this bumps MSRV with parking_lot feature enabled to 1.36.0).
• add OnceCell::take.
• upgrade crossbeam utils (private dependency) to 0.7.

• remove unnecessary F: fmt::Debug bound from impl fmt::Debug for Lazy<T, F>.

• Lazy<T> now implements DerefMut.
• update implementation according to the latest changes in std.

• add sync::OnceCell::get_unchecked.

• implement Default for Lazy: it creates an empty Lazy<T> which is initialized with T::default on first access.
• add OnceCell::get_mut.

• actually add #![no_std] attribute if std feature is not enabled.

• fix unsoundness in Lazy<T> if the initializing function panics. Thanks @xfix!
• implement RefUnwindSafe for Lazy.
• share more code between std and parking_lot implementations.
• add F.A.Q section to the docs.

• remove parking_lot from the list of default features.
• add std default feature. Without std, only unsync module is supported.
• implement Eq for OnceCell.
• fix wrong Sync bound on sync::Lazy.
• run the whole test suite with miri.

• New implementation of sync::OnceCell if parking_lot feature is disabled. It now employs a hand-rolled variant of std::sync::Once.
• sync::OnceCell::get_or_try_init works without parking_lot as well!
• document the effects of parking_lot feature: same performance but smaller types.

• Updated Lazy's Deref impl to requires only FnOnce instead of Fn

• Lazy requires only FnOnce instead of Fn

• nicer fmt::Debug implementation

• update parking_lot to 0.9.0
• fix stacked borrows violation in unsync::OnceCell::get
• implement Clone for sync::OnceCell<T> where T: Clone

• add OnceCell::into_inner which consumes a cell and returns an option

• implement sync::OnceCell::get_or_try_init if parking_lot feature is enabled
• switch internal unsafe implementation of sync::OnceCell from Once to Mutex
• sync::OnceCell::get_or_init is twice as fast if cell is already initialized
• implement std::panic::RefUnwindSafe and std::panic::UnwindSafe for OnceCell
• better document behavior around panics

• MSRV is now 1.31.1
• Lazy::new and OnceCell::new are now const-fns
• unsync_lazy and sync_lazy macros are removed

• update crossbeam-utils to 0.6
• enable bors-ng

• cells implement PartialEq and From
• MSRV is down to 1.24.1
• update parking_lot to 0.7.1

• unsync::OnceCell<T> is Clone if T is Clone.

• No changelog until this point :(