// SPDX-License-Identifier: Apache-2.0 OR MIT //! # The Rust core allocation and collections library//!//! This library provides smart pointers and collections for managing//! heap-allocated values.//!//! This library, like libcore, normally doesn’t need to be used directly//! since its contents are re-exported in the [`std` crate](../std/index.html).//! Crates that use the `#![no_std]` attribute however will typically//! not depend on `std`, so they’d use this crate instead.//!//! ## Boxed values//!//! The [`Box`] type is a smart pointer type. There can only be one owner of a//! [`Box`], and the owner can decide to mutate the contents, which live on the//! heap.//!//! This type can be sent among threads efficiently as the size of a `Box` value//! is the same as that of a pointer. Tree-like data structures are often built//! with boxes because each node often has only one owner, the parent.//!//! ## Reference counted pointers//!//! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended//! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and//! only allows access to `&T`, a shared reference.//!//! This type is useful when inherited mutability (such as using [`Box`]) is too//! constraining for an application, and is often paired with the [`Cell`] or//! [`RefCell`] types in order to allow mutation.//!//! ## Atomically reference counted pointers//!//! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It//! provides all the same functionality of [`Rc`], except it requires that the//! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself//! sendable while [`Rc<T>`][`Rc`] is not.//!//! This type allows for shared access to the contained data, and is often//! paired with synchronization primitives such as mutexes to allow mutation of//! shared resources.//!//! ## Collections//!//! Implementations of the most common general purpose data structures are//! defined in this library. They are re-exported through the//! [standard collections library](../std/collections/index.html).//!//! ## Heap interfaces//!//! The [`alloc`](alloc/index.html) module defines the low-level interface to the//! default global allocator. It is not compatible with the libc allocator API.//!//! [`Arc`]: sync//! [`Box`]: boxed//! [`Cell`]: core::cell//! [`Rc`]: rc//! [`RefCell`]: core::cell // To run liballoc tests without x.py without ending up with two copies of liballoc, Miri needs to be// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.// rustc itself never sets the feature, so this line has no affect there.#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]#![allow(unused_attributes)]#![stable(feature = "alloc", since = "1.36.0")]#![doc(    html_playground_url = "https://play.rust-lang.org/",    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",    test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]#![doc(cfg_hide(    not(test),    not(any(test, bootstrap)),    any(not(feature = "miri-test-libstd"), test, doctest),    no_global_oom_handling,    not(no_global_oom_handling),    target_has_atomic = "ptr"))]#![no_std]#![needs_allocator]//// Lints:#![deny(unsafe_op_in_unsafe_fn)]#![warn(deprecated_in_future)]#![warn(missing_debug_implementations)]#![warn(missing_docs)]#![allow(explicit_outlives_requirements)]//// Library features:#![cfg_attr(not(no_global_oom_handling), feature(alloc_c_string))]#![feature(alloc_layout_extra)]#![feature(allocator_api)]#![feature(array_chunks)]#![feature(array_methods)]#![feature(array_windows)]#![feature(assert_matches)]#![feature(async_iterator)]#![feature(coerce_unsized)]#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]#![feature(const_box)]#![cfg_attr(not(no_global_oom_handling), feature(const_btree_new))]#![feature(const_cow_is_borrowed)]#![feature(const_convert)]#![feature(const_size_of_val)]#![feature(const_align_of_val)]#![feature(const_ptr_read)]#![feature(const_maybe_uninit_write)]#![feature(const_maybe_uninit_as_mut_ptr)]#![feature(const_refs_to_cell)]#![feature(core_c_str)]#![feature(core_intrinsics)]#![feature(core_ffi_c)]#![feature(const_eval_select)]#![feature(const_pin)]#![feature(cstr_from_bytes_until_nul)]#![feature(dispatch_from_dyn)]#![feature(exact_size_is_empty)]#![feature(extend_one)]#![feature(fmt_internals)]#![feature(fn_traits)]#![feature(hasher_prefixfree_extras)]#![feature(inplace_iteration)]#![feature(iter_advance_by)]#![feature(layout_for_ptr)]#![feature(maybe_uninit_slice)]#![cfg_attr(test, feature(new_uninit))]#![feature(nonnull_slice_from_raw_parts)]#![feature(pattern)]#![feature(ptr_internals)]#![feature(ptr_metadata)]#![feature(ptr_sub_ptr)]#![feature(receiver_trait)]#![feature(set_ptr_value)]#![feature(slice_group_by)]#![feature(slice_ptr_get)]#![feature(slice_ptr_len)]#![feature(slice_range)]#![feature(str_internals)]#![feature(strict_provenance)]#![feature(trusted_len)]#![feature(trusted_random_access)]#![feature(try_trait_v2)]#![feature(unchecked_math)]#![feature(unicode_internals)]#![feature(unsize)]//// Language features:#![feature(allocator_internals)]#![feature(allow_internal_unstable)]#![feature(associated_type_bounds)]#![feature(box_syntax)]#![feature(cfg_sanitize)]#![feature(const_deref)]#![feature(const_mut_refs)]#![feature(const_ptr_write)]#![feature(const_precise_live_drops)]#![feature(const_trait_impl)]#![feature(const_try)]#![feature(dropck_eyepatch)]#![feature(exclusive_range_pattern)]#![feature(fundamental)]#![cfg_attr(not(test), feature(generator_trait))]#![feature(hashmap_internals)]#![feature(lang_items)]#![feature(let_else)]#![feature(min_specialization)]#![feature(negative_impls)]#![feature(never_type)]#![feature(nll)] // Not necessary, but here to test the `nll` feature.#![feature(rustc_allow_const_fn_unstable)]#![feature(rustc_attrs)]#![feature(slice_internals)]#![feature(staged_api)]#![cfg_attr(test, feature(test))]#![feature(unboxed_closures)]#![feature(unsized_fn_params)]#![feature(c_unwind)]//// Rustdoc features:#![feature(doc_cfg)]#![feature(doc_cfg_hide)]// Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]`// blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad// that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs// from other crates, but since this can only appear for lang items, it doesn't seem worth fixing.#![feature(intra_doc_pointers)] // Allow testing this library#[cfg(test)]#[macro_use]extern crate std;#[cfg(test)]extern crate test; // Module with internal macros used by other modules (needs to be included before other modules).#[cfg(not(no_macros))]#[macro_use]mod macros; mod raw_vec; // Heaps provided for low-level allocation strategies pub mod alloc; // Primitive types using the heaps above // Need to conditionally define the mod from `boxed.rs` to avoid// duplicating the lang-items when building in test cfg; but also need// to allow code to have `use boxed::Box;` declarations.#[cfg(not(test))]pub mod boxed;#[cfg(test)]mod boxed {    pub use std::boxed::Box;}pub mod borrow;pub mod collections;#[cfg(not(no_global_oom_handling))]pub mod ffi;#[cfg(not(no_fmt))]pub mod fmt;#[cfg(not(no_rc))]pub mod rc;pub mod slice;#[cfg(not(no_str))]pub mod str;#[cfg(not(no_string))]pub mod string;#[cfg(not(no_sync))]#[cfg(target_has_atomic = "ptr")]pub mod sync;#[cfg(all(not(no_global_oom_handling), target_has_atomic = "ptr"))]pub mod task;#[cfg(test)]mod tests;pub mod vec; #[doc(hidden)]#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]pub mod __export {    pub use core::format_args;}