projects/linux·blob v6.3-rc4 · refs

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1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3//! # The Rust core allocation and collections library
4//!
5//! This library provides smart pointers and collections for managing
6//! heap-allocated values.
7//!
8//! This library, like libcore, normally doesn’t need to be used directly
9//! since its contents are re-exported in the [`std` crate](../std/index.html).
10//! Crates that use the `#![no_std]` attribute however will typically
11//! not depend on `std`, so they’d use this crate instead.
12//!
13//! ## Boxed values
14//!
15//! The [`Box`] type is a smart pointer type. There can only be one owner of a
16//! [`Box`], and the owner can decide to mutate the contents, which live on the
17//! heap.
18//!
19//! This type can be sent among threads efficiently as the size of a `Box` value
20//! is the same as that of a pointer. Tree-like data structures are often built
21//! with boxes because each node often has only one owner, the parent.
22//!
23//! ## Reference counted pointers
24//!
25//! The [`Rc`] type is a non-threadsafe reference-counted pointer type intended
26//! for sharing memory within a thread. An [`Rc`] pointer wraps a type, `T`, and
27//! only allows access to `&T`, a shared reference.
28//!
29//! This type is useful when inherited mutability (such as using [`Box`]) is too
30//! constraining for an application, and is often paired with the [`Cell`] or
31//! [`RefCell`] types in order to allow mutation.
32//!
33//! ## Atomically reference counted pointers
34//!
35//! The [`Arc`] type is the threadsafe equivalent of the [`Rc`] type. It
36//! provides all the same functionality of [`Rc`], except it requires that the
37//! contained type `T` is shareable. Additionally, [`Arc<T>`][`Arc`] is itself
38//! sendable while [`Rc<T>`][`Rc`] is not.
39//!
40//! This type allows for shared access to the contained data, and is often
41//! paired with synchronization primitives such as mutexes to allow mutation of
42//! shared resources.
43//!
44//! ## Collections
45//!
46//! Implementations of the most common general purpose data structures are
47//! defined in this library. They are re-exported through the
48//! [standard collections library](../std/collections/index.html).
49//!
50//! ## Heap interfaces
51//!
52//! The [`alloc`](alloc/index.html) module defines the low-level interface to the
53//! default global allocator. It is not compatible with the libc allocator API.
54//!
55//! [`Arc`]: sync
56//! [`Box`]: boxed
57//! [`Cell`]: core::cell
58//! [`Rc`]: rc
59//! [`RefCell`]: core::cell
60
61// To run liballoc tests without x.py without ending up with two copies of liballoc, Miri needs to be
62// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
63// rustc itself never sets the feature, so this line has no affect there.
64#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
65#![allow(unused_attributes)]
66#![stable(feature = "alloc", since = "1.36.0")]
67#![doc(
68 html_playground_url = "https://play.rust-lang.org/",
69 issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
70 test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
71)]
72#![doc(cfg_hide(
73 not(test),
74 not(any(test, bootstrap)),
75 any(not(feature = "miri-test-libstd"), test, doctest),
76 no_global_oom_handling,
77 not(no_global_oom_handling),
78 target_has_atomic = "ptr"
79))]
80#![no_std]
81#![needs_allocator]
82//
83// Lints:
84#![deny(unsafe_op_in_unsafe_fn)]
85#![warn(deprecated_in_future)]
86#![warn(missing_debug_implementations)]
87#![warn(missing_docs)]
88#![allow(explicit_outlives_requirements)]
89//
90// Library features:
91#![cfg_attr(not(no_global_oom_handling), feature(alloc_c_string))]
92#![feature(alloc_layout_extra)]
93#![feature(allocator_api)]
94#![feature(array_chunks)]
95#![feature(array_methods)]
96#![feature(array_windows)]
97#![feature(assert_matches)]
98#![feature(async_iterator)]
99#![feature(coerce_unsized)]
100#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
101#![feature(const_box)]
102#![cfg_attr(not(no_global_oom_handling), feature(const_btree_new))]
103#![cfg_attr(not(no_borrow), feature(const_cow_is_borrowed))]
104#![feature(const_convert)]
105#![feature(const_size_of_val)]
106#![feature(const_align_of_val)]
107#![feature(const_ptr_read)]
108#![feature(const_maybe_uninit_write)]
109#![feature(const_maybe_uninit_as_mut_ptr)]
110#![feature(const_refs_to_cell)]
111#![feature(core_c_str)]
112#![feature(core_intrinsics)]
113#![feature(core_ffi_c)]
114#![feature(const_eval_select)]
115#![feature(const_pin)]
116#![feature(cstr_from_bytes_until_nul)]
117#![feature(dispatch_from_dyn)]
118#![feature(exact_size_is_empty)]
119#![feature(extend_one)]
120#![feature(fmt_internals)]
121#![feature(fn_traits)]
122#![feature(hasher_prefixfree_extras)]
123#![feature(inplace_iteration)]
124#![feature(iter_advance_by)]
125#![feature(layout_for_ptr)]
126#![feature(maybe_uninit_slice)]
127#![cfg_attr(test, feature(new_uninit))]
128#![feature(nonnull_slice_from_raw_parts)]
129#![feature(pattern)]
130#![feature(ptr_internals)]
131#![feature(ptr_metadata)]
132#![feature(ptr_sub_ptr)]
133#![feature(receiver_trait)]
134#![feature(set_ptr_value)]
135#![feature(slice_group_by)]
136#![feature(slice_ptr_get)]
137#![feature(slice_ptr_len)]
138#![feature(slice_range)]
139#![feature(str_internals)]
140#![feature(strict_provenance)]
141#![feature(trusted_len)]
142#![feature(trusted_random_access)]
143#![feature(try_trait_v2)]
144#![feature(unchecked_math)]
145#![feature(unicode_internals)]
146#![feature(unsize)]
147//
148// Language features:
149#![feature(allocator_internals)]
150#![feature(allow_internal_unstable)]
151#![feature(associated_type_bounds)]
152#![feature(box_syntax)]
153#![feature(cfg_sanitize)]
154#![feature(const_deref)]
155#![feature(const_mut_refs)]
156#![feature(const_ptr_write)]
157#![feature(const_precise_live_drops)]
158#![feature(const_trait_impl)]
159#![feature(const_try)]
160#![feature(dropck_eyepatch)]
161#![feature(exclusive_range_pattern)]
162#![feature(fundamental)]
163#![cfg_attr(not(test), feature(generator_trait))]
164#![feature(hashmap_internals)]
165#![feature(lang_items)]
166#![feature(let_else)]
167#![feature(min_specialization)]
168#![feature(negative_impls)]
169#![feature(never_type)]
170#![feature(nll)] // Not necessary, but here to test the `nll` feature.
171#![feature(rustc_allow_const_fn_unstable)]
172#![feature(rustc_attrs)]
173#![feature(slice_internals)]
174#![feature(staged_api)]
175#![cfg_attr(test, feature(test))]
176#![feature(unboxed_closures)]
177#![feature(unsized_fn_params)]
178#![feature(c_unwind)]
179//
180// Rustdoc features:
181#![feature(doc_cfg)]
182#![feature(doc_cfg_hide)]
183// Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]`
184// blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad
185// that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs
186// from other crates, but since this can only appear for lang items, it doesn't seem worth fixing.
187#![feature(intra_doc_pointers)]
188
189// Allow testing this library
190#[cfg(test)]
191#[macro_use]
192extern crate std;
193#[cfg(test)]
194extern crate test;
195
196// Module with internal macros used by other modules (needs to be included before other modules).
197#[cfg(not(no_macros))]
198#[macro_use]
199mod macros;
200
201mod raw_vec;
202
203// Heaps provided for low-level allocation strategies
204
205pub mod alloc;
206
207// Primitive types using the heaps above
208
209// Need to conditionally define the mod from `boxed.rs` to avoid
210// duplicating the lang-items when building in test cfg; but also need
211// to allow code to have `use boxed::Box;` declarations.
212#[cfg(not(test))]
213pub mod boxed;
214#[cfg(test)]
215mod boxed {
216 pub use std::boxed::Box;
217}
218#[cfg(not(no_borrow))]
219pub mod borrow;
220pub mod collections;
221#[cfg(not(no_global_oom_handling))]
222pub mod ffi;
223#[cfg(not(no_fmt))]
224pub mod fmt;
225#[cfg(not(no_rc))]
226pub mod rc;
227pub mod slice;
228#[cfg(not(no_str))]
229pub mod str;
230#[cfg(not(no_string))]
231pub mod string;
232#[cfg(not(no_sync))]
233#[cfg(target_has_atomic = "ptr")]
234pub mod sync;
235#[cfg(all(not(no_global_oom_handling), target_has_atomic = "ptr"))]
236pub mod task;
237#[cfg(test)]
238mod tests;
239pub mod vec;
240
241#[doc(hidden)]
242#[unstable(feature = "liballoc_internals", issue = "none", reason = "implementation detail")]
243pub mod __export {
244 pub use core::format_args;
245}