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lib.rs

1//! # The Rust Standard Library
2//!
3//! The Rust Standard Library is the foundation of portable Rust software, a
4//! set of minimal and battle-tested shared abstractions for the [broader Rust
5//! ecosystem][crates.io]. It offers core types, like [`Vec<T>`] and
6//! [`Option<T>`], library-defined [operations on language
7//! primitives](#primitives), [standard macros](#macros), [I/O] and
8//! [multithreading], among [many other things][other].
9//!
10//! `std` is available to all Rust crates by default. Therefore, the
11//! standard library can be accessed in [`use`] statements through the path
12//! `std`, as in [`use std::env`].
13//!
14//! # How to read this documentation
15//!
16//! If you already know the name of what you are looking for, the fastest way to
17//! find it is to use the <a href="#" onclick="window.searchState.focus();">search
18//! button</a> at the top of the page.
19//!
20//! Otherwise, you may want to jump to one of these useful sections:
21//!
22//! * [`std::*` modules](#modules)
23//! * [Primitive types](#primitives)
24//! * [Standard macros](#macros)
25//! * [The Rust Prelude]
26//!
27//! If this is your first time, the documentation for the standard library is
28//! written to be casually perused. Clicking on interesting things should
29//! generally lead you to interesting places. Still, there are important bits
30//! you don't want to miss, so read on for a tour of the standard library and
31//! its documentation!
32//!
33//! Once you are familiar with the contents of the standard library you may
34//! begin to find the verbosity of the prose distracting. At this stage in your
35//! development you may want to press the
36//! "<svg style="width:0.75rem;height:0.75rem" viewBox="0 0 12 12" stroke="currentColor" fill="none"><path d="M2,2l4,4l4,-4M2,6l4,4l4,-4"/></svg>&nbsp;Summary"
37//! button near the top of the page to collapse it into a more skimmable view.
38//!
39//! While you are looking at the top of the page, also notice the
40//! "Source" link. Rust's API documentation comes with the source
41//! code and you are encouraged to read it. The standard library source is
42//! generally high quality and a peek behind the curtains is
43//! often enlightening.
44//!
45//! # What is in the standard library documentation?
46//!
47//! First of all, The Rust Standard Library is divided into a number of focused
48//! modules, [all listed further down this page](#modules). These modules are
49//! the bedrock upon which all of Rust is forged, and they have mighty names
50//! like [`std::slice`] and [`std::cmp`]. Modules' documentation typically
51//! includes an overview of the module along with examples, and are a smart
52//! place to start familiarizing yourself with the library.
53//!
54//! Second, implicit methods on [primitive types] are documented here. This can
55//! be a source of confusion for two reasons:
56//!
57//! 1. While primitives are implemented by the compiler, the standard library
58//!    implements methods directly on the primitive types (and it is the only
59//!    library that does so), which are [documented in the section on
60//!    primitives](#primitives).
61//! 2. The standard library exports many modules *with the same name as
62//!    primitive types*. These define additional items related to the primitive
63//!    type, but not the all-important methods.
64//!
65//! So for example there is a [page for the primitive type
66//! `char`](primitive::char) that lists all the methods that can be called on
67//! characters (very useful), and there is a [page for the module
68//! `std::char`](crate::char) that documents iterator and error types created by these methods
69//! (rarely useful).
70//!
71//! Note the documentation for the primitives [`str`] and [`[T]`][prim@slice] (also
72//! called 'slice'). Many method calls on [`String`] and [`Vec<T>`] are actually
73//! calls to methods on [`str`] and [`[T]`][prim@slice] respectively, via [deref
74//! coercions][deref-coercions].
75//!
76//! Third, the standard library defines [The Rust Prelude], a small collection
77//! of items - mostly traits - that are imported into every module of every
78//! crate. The traits in the prelude are pervasive, making the prelude
79//! documentation a good entry point to learning about the library.
80//!
81//! And finally, the standard library exports a number of standard macros, and
82//! [lists them on this page](#macros) (technically, not all of the standard
83//! macros are defined by the standard library - some are defined by the
84//! compiler - but they are documented here the same). Like the prelude, the
85//! standard macros are imported by default into all crates.
86//!
87//! # Contributing changes to the documentation
88//!
89//! Check out the Rust contribution guidelines [here](
90//! https://rustc-dev-guide.rust-lang.org/contributing.html#writing-documentation).
91//! The source for this documentation can be found on
92//! [GitHub](https://github.com/rust-lang/rust) in the 'library/std/' directory.
93//! To contribute changes, make sure you read the guidelines first, then submit
94//! pull-requests for your suggested changes.
95//!
96//! Contributions are appreciated! If you see a part of the docs that can be
97//! improved, submit a PR, or chat with us first on [Zulip][t-libs-zulip]
98//! #t-libs.
99//!
100//! # A Tour of The Rust Standard Library
101//!
102//! The rest of this crate documentation is dedicated to pointing out notable
103//! features of The Rust Standard Library.
104//!
105//! ## Containers and collections
106//!
107//! The [`option`] and [`result`] modules define optional and error-handling
108//! types, [`Option<T>`] and [`Result<T, E>`]. The [`iter`] module defines
109//! Rust's iterator trait, [`Iterator`], which works with the [`for`] loop to
110//! access collections.
111//!
112//! The standard library exposes three common ways to deal with contiguous
113//! regions of memory:
114//!
115//! * [`Vec<T>`] - A heap-allocated *vector* that is resizable at runtime.
116//! * [`[T; N]`][prim@array] - An inline *array* with a fixed size at compile time.
117//! * [`[T]`][prim@slice] - A dynamically sized *slice* into any other kind of contiguous
118//!   storage, whether heap-allocated or not.
119//!
120//! Slices can only be handled through some kind of *pointer*, and as such come
121//! in many flavors such as:
122//!
123//! * `&[T]` - *shared slice*
124//! * `&mut [T]` - *mutable slice*
125//! * [`Box<[T]>`][owned slice] - *owned slice*
126//!
127//! [`str`], a UTF-8 string slice, is a primitive type, and the standard library
128//! defines many methods for it. Rust [`str`]s are typically accessed as
129//! immutable references: `&str`. Use the owned [`String`] for building and
130//! mutating strings.
131//!
132//! For converting to strings use the [`format!`] macro, and for converting from
133//! strings use the [`FromStr`] trait.
134//!
135//! Data may be shared by placing it in a reference-counted box or the [`Rc`]
136//! type, and if further contained in a [`Cell`] or [`RefCell`], may be mutated
137//! as well as shared. Likewise, in a concurrent setting it is common to pair an
138//! atomically-reference-counted box, [`Arc`], with a [`Mutex`] to get the same
139//! effect.
140//!
141//! The [`collections`] module defines maps, sets, linked lists and other
142//! typical collection types, including the common [`HashMap<K, V>`].
143//!
144//! ## Platform abstractions and I/O
145//!
146//! Besides basic data types, the standard library is largely concerned with
147//! abstracting over differences in common platforms, most notably Windows and
148//! Unix derivatives.
149//!
150//! Common types of I/O, including [files], [TCP], and [UDP], are defined in
151//! the [`io`], [`fs`], and [`net`] modules.
152//!
153//! The [`thread`] module contains Rust's threading abstractions. [`sync`]
154//! contains further primitive shared memory types, including [`atomic`], [`mpmc`] and
155//! [`mpsc`], which contains the channel types for message passing.
156//!
157//! # Use before and after `main()`
158//!
159//! Many parts of the standard library are expected to work before and after `main()`;
160//! but this is not guaranteed or ensured by tests. It is recommended that you write your own tests
161//! and run them on each platform you wish to support.
162//! This means that use of `std` before/after main, especially of features that interact with the
163//! OS or global state, is exempted from stability and portability guarantees and instead only
164//! provided on a best-effort basis. Nevertheless bug reports are appreciated.
165//!
166//! On the other hand `core` and `alloc` are most likely to work in such environments with
167//! the caveat that any hookable behavior such as panics, oom handling or allocators will also
168//! depend on the compatibility of the hooks.
169//!
170//! Some features may also behave differently outside main, e.g. stdio could become unbuffered,
171//! some panics might turn into aborts, backtraces might not get symbolicated or similar.
172//!
173//! Non-exhaustive list of known limitations:
174//!
175//! - after-main use of thread-locals, which also affects additional features:
176//!   - [`thread::current()`]
177//! - under UNIX, before main, file descriptors 0, 1, and 2 may be unchanged
178//!   (they are guaranteed to be open during main,
179//!    and are opened to /dev/null O_RDWR if they weren't open on program start)
180//!
181//!
182//! [I/O]: io
183//! [TCP]: net::TcpStream
184//! [The Rust Prelude]: prelude
185//! [UDP]: net::UdpSocket
186//! [`Arc`]: sync::Arc
187//! [owned slice]: boxed
188//! [`Cell`]: cell::Cell
189//! [`FromStr`]: str::FromStr
190//! [`HashMap<K, V>`]: collections::HashMap
191//! [`Mutex`]: sync::Mutex
192//! [`Option<T>`]: option::Option
193//! [`Rc`]: rc::Rc
194//! [`RefCell`]: cell::RefCell
195//! [`Result<T, E>`]: result::Result
196//! [`Vec<T>`]: vec::Vec
197//! [`atomic`]: sync::atomic
198//! [`for`]: ../book/ch03-05-control-flow.html#looping-through-a-collection-with-for
199//! [`str`]: prim@str
200//! [`mpmc`]: sync::mpmc
201//! [`mpsc`]: sync::mpsc
202//! [`std::cmp`]: cmp
203//! [`std::slice`]: mod@slice
204//! [`use std::env`]: env/index.html
205//! [`use`]: ../book/ch07-02-defining-modules-to-control-scope-and-privacy.html
206//! [crates.io]: https://crates.io
207//! [deref-coercions]: ../book/ch15-02-deref.html#implicit-deref-coercions-with-functions-and-methods
208//! [files]: fs::File
209//! [multithreading]: thread
210//! [other]: #what-is-in-the-standard-library-documentation
211//! [primitive types]: ../book/ch03-02-data-types.html
212//! [t-libs-zulip]: https://rust-lang.zulipchat.com/#narrow/channel/219381-t-libs/
213//! [array]: prim@array
214//! [slice]: prim@slice
215
216#![cfg_attr(not(restricted_std), stable(feature = "rust1", since = "1.0.0"))]
217#![cfg_attr(
218    restricted_std,
219    unstable(
220        feature = "restricted_std",
221        issue = "none",
222        reason = "You have attempted to use a standard library built for a platform that it doesn't \
223            know how to support. Consider building it for a known environment, disabling it with \
224            `#![no_std]` or overriding this warning by enabling this feature."
225    )
226)]
227#![rustc_preserve_ub_checks]
228#![doc(
229    html_playground_url = "https://play.rust-lang.org/",
230    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
231    test(no_crate_inject, attr(deny(warnings))),
232    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
233)]
234#![doc(rust_logo)]
235#![doc(auto_cfg(hide(no_global_oom_handling)))]
236// Don't link to std. We are std.
237#![no_std]
238// Tell the compiler to link to either panic_abort or panic_unwind
239#![needs_panic_runtime]
240//
241// Lints:
242#![warn(deprecated_in_future)]
243#![warn(missing_docs)]
244#![warn(unreachable_pub)]
245#![warn(missing_debug_implementations)]
246#![allow(explicit_outlives_requirements)]
247#![allow(internal_features)]
248#![deny(implicit_provenance_casts)]
249#![deny(unsafe_op_in_unsafe_fn)]
250#![allow(rustdoc::redundant_explicit_links)]
251#![warn(rustdoc::unescaped_backticks)]
252// Ensure that std can be linked against panic_abort despite compiled with `-C panic=unwind`
253#![deny(ffi_unwind_calls)]
254// std may use features in a platform-specific way
255#![allow(unused_features)]
256//
257// Features:
258#![cfg_attr(
259    test,
260    feature(internal_output_capture, print_internals, super_let, update_panic_count, rt)
261)]
262#![cfg_attr(
263    all(target_vendor = "fortanix", target_env = "sgx"),
264    feature(slice_index_methods, coerce_unsized, sgx_platform)
265)]
266#![cfg_attr(all(test, target_os = "uefi"), feature(uefi_std))]
267#![cfg_attr(target_family = "wasm", feature(stdarch_wasm_atomic_wait))]
268#![cfg_attr(target_arch = "wasm64", feature(simd_wasm64))]
269//
270// Language features:
271// tidy-alphabetical-start
272#![feature(alloc_error_handler)]
273#![feature(allocator_internals)]
274#![feature(allow_internal_unsafe)]
275#![feature(allow_internal_unstable)]
276#![feature(asm_experimental_arch)]
277#![feature(autodiff)]
278#![feature(cfg_sanitizer_cfi)]
279#![feature(cfg_target_has_threads)]
280#![feature(cfg_target_thread_local)]
281#![feature(cfi_encoding)]
282#![feature(const_trait_impl)]
283#![feature(decl_macro)]
284#![feature(deprecated_suggestion)]
285#![feature(diagnostic_on_move)]
286#![feature(doc_cfg)]
287#![feature(doc_masked)]
288#![feature(doc_notable_trait)]
289#![feature(dropck_eyepatch)]
290#![feature(f16)]
291#![feature(f128)]
292#![feature(ffi_const)]
293#![feature(gpu_offload)]
294#![feature(impl_restriction)]
295#![feature(intra_doc_pointers)]
296#![feature(lang_items)]
297#![feature(link_cfg)]
298#![feature(linkage)]
299#![feature(macro_metavar_expr_concat)]
300#![feature(min_specialization)]
301#![feature(must_not_suspend)]
302#![feature(needs_panic_runtime)]
303#![feature(negative_impls)]
304#![feature(prelude_import)]
305#![feature(rustc_attrs)]
306#![feature(rustdoc_internals)]
307#![feature(staged_api)]
308#![feature(stmt_expr_attributes)]
309#![feature(strict_provenance_lints)]
310#![feature(thread_local)]
311#![feature(try_blocks)]
312#![feature(try_trait_v2)]
313#![feature(type_alias_impl_trait)]
314// tidy-alphabetical-end
315//
316// Library features (core):
317// tidy-alphabetical-start
318#![feature(borrowed_buf_init)]
319#![feature(byte_str)]
320#![feature(byte_str_internals)]
321#![feature(c_size_t)]
322#![feature(can_vector)]
323#![feature(cast_maybe_uninit)]
324#![feature(char_internals)]
325#![feature(clone_to_uninit)]
326#![feature(const_clone)]
327#![feature(const_convert)]
328#![feature(const_default)]
329#![feature(core_float_math)]
330#![feature(core_intrinsics)]
331#![feature(core_io)]
332#![feature(core_io_borrowed_buf)]
333#![feature(core_io_internals)]
334#![feature(cursor_split)]
335#![feature(derive_const)]
336#![feature(duration_constants)]
337#![feature(error_generic_member_access)]
338#![feature(error_iter)]
339#![feature(exact_size_is_empty)]
340#![feature(extend_one)]
341#![feature(float_gamma)]
342#![feature(float_minimum_maximum)]
343#![feature(fmt_internals)]
344#![feature(fn_static)]
345#![feature(formatting_options)]
346#![feature(generic_atomic)]
347#![feature(hash_map_internals)]
348#![feature(hash_map_macro)]
349#![feature(hasher_prefixfree_extras)]
350#![feature(hashmap_internals)]
351#![feature(hint_must_use)]
352#![feature(int_from_ascii)]
353#![feature(io_error_inprogress)]
354#![feature(io_error_input_output_error)]
355#![feature(io_error_more)]
356#![feature(io_error_too_many_open_files)]
357#![feature(io_error_uncategorized)]
358#![feature(io_slice_as_bytes)]
359#![feature(ip)]
360#![feature(ipv6_hop_limit)]
361#![feature(iter_advance_by)]
362#![feature(iter_next_chunk)]
363#![feature(maybe_dangling)]
364#![feature(maybe_uninit_array_assume_init)]
365#![feature(maybe_uninit_fill)]
366#![feature(once_lazy_lock_get_unchecked)]
367#![feature(panic_can_unwind)]
368#![feature(panic_internals)]
369#![feature(pin_coerce_unsized_trait)]
370#![feature(pointer_is_aligned_to)]
371#![feature(portable_simd)]
372#![feature(ptr_as_uninit)]
373#![feature(ptr_mask)]
374#![feature(random)]
375#![feature(raw_os_error_ty)]
376#![feature(register_tool)]
377#![feature(seek_io_take_position)]
378#![feature(seek_stream_len)]
379#![feature(share_trait)]
380#![feature(slice_internals)]
381#![feature(slice_ptr_get)]
382#![feature(slice_range)]
383#![feature(std_internals)]
384#![feature(str_internals)]
385#![feature(sync_unsafe_cell)]
386#![feature(temporary_niche_types)]
387#![feature(ub_checks)]
388#![feature(uint_carryless_mul)]
389#![feature(unsafe_pinned)]
390#![feature(used_with_arg)]
391#![feature(write_all_vectored)]
392// tidy-alphabetical-end
393//
394// Library features (alloc):
395// tidy-alphabetical-start
396#![feature(alloc_io)]
397#![feature(allocator_ext)]
398#![feature(buf_read_has_data_left)]
399#![feature(clone_from_ref)]
400#![feature(get_mut_unchecked)]
401#![feature(map_try_insert)]
402#![feature(read_buf)]
403#![feature(slice_concat_trait)]
404#![feature(thin_box)]
405#![feature(try_reserve_kind)]
406#![feature(try_with_capacity)]
407#![feature(unique_rc_arc)]
408#![feature(wtf8_internals)]
409// tidy-alphabetical-end
410//
411// Library features (unwind):
412// tidy-alphabetical-start
413#![feature(panic_unwind)]
414// tidy-alphabetical-end
415//
416// Library features (std_detect):
417// tidy-alphabetical-start
418#![feature(stdarch_internal)]
419// tidy-alphabetical-end
420//
421// Only for re-exporting:
422// tidy-alphabetical-start
423#![feature(async_iterator)]
424#![feature(cfg_accessible)]
425#![feature(cfg_eval)]
426#![feature(concat_bytes)]
427#![feature(const_format_args)]
428#![feature(custom_test_frameworks)]
429#![feature(edition_panic)]
430#![feature(format_args_nl)]
431#![feature(log_syntax)]
432#![feature(test)]
433#![feature(trace_macros)]
434// tidy-alphabetical-end
435//
436// Only used in tests/benchmarks:
437//
438// Only for const-ness:
439// tidy-alphabetical-start
440#![feature(io_const_error)]
441// tidy-alphabetical-end
442//
443#![default_lib_allocator]
444// Removed features
445#![unstable_removed(
446    feature = "concat_idents",
447    reason = "Replaced by the macro_metavar_expr_concat feature",
448    link = "https://github.com/rust-lang/rust/issues/29599#issuecomment-2986866250",
449    since = "1.90.0"
450)]
451// tidy-alphabetical-start
452#![register_tool(lint)]
453// tidy-alphabetical-end
454//
455
456// The Rust prelude
457// The compiler expects the prelude definition to be defined before its use statement.
458pub mod prelude;
459
460// Explicitly import the prelude. The compiler uses this same unstable attribute
461// to import the prelude implicitly when building crates that depend on std.
462#[prelude_import]
463#[allow(unused)]
464use prelude::rust_2024::*;
465
466// Access to Bencher, etc.
467#[cfg(test)]
468extern crate test;
469
470#[allow(unused_imports)] // macros from `alloc` are not used on all platforms
471#[macro_use]
472extern crate alloc as alloc_crate;
473
474// Many compiler tests depend on libc being pulled in by std
475// so include it here even if it's unused.
476#[doc(masked)]
477#[allow(unused_extern_crates)]
478#[cfg(not(all(windows, target_env = "msvc")))]
479extern crate libc;
480
481// We always need an unwinder currently for backtraces
482#[doc(masked)]
483#[allow(unused_extern_crates)]
484extern crate unwind;
485
486// FIXME: #94122 this extern crate definition only exist here to stop
487// miniz_oxide docs leaking into std docs. Find better way to do it.
488// Remove exclusion from tidy platform check when this removed.
489#[doc(masked)]
490#[allow(unused_extern_crates)]
491#[cfg(all(
492    not(all(windows, target_env = "msvc", not(target_vendor = "uwp"))),
493    feature = "miniz_oxide"
494))]
495extern crate miniz_oxide;
496
497// During testing, this crate is not actually the "real" std library, but rather
498// it links to the real std library, which was compiled from this same source
499// code. So any lang items std defines are conditionally excluded (or else they
500// would generate duplicate lang item errors), and any globals it defines are
501// _not_ the globals used by "real" std. So this import, defined only during
502// testing gives test-std access to real-std lang items and globals. See #2912
503#[cfg(test)]
504extern crate std as realstd;
505
506// The standard macros that are not built-in to the compiler.
507#[macro_use]
508mod macros;
509
510// The runtime entry point and a few unstable public functions used by the
511// compiler
512#[macro_use]
513pub mod rt;
514
515#[stable(feature = "rust1", since = "1.0.0")]
516pub use core::any;
517#[stable(feature = "core_array", since = "1.35.0")]
518pub use core::array;
519#[unstable(feature = "async_iterator", issue = "79024")]
520pub use core::async_iter;
521#[stable(feature = "rust1", since = "1.0.0")]
522pub use core::cell;
523#[stable(feature = "rust1", since = "1.0.0")]
524pub use core::char;
525#[stable(feature = "rust1", since = "1.0.0")]
526pub use core::clone;
527#[stable(feature = "rust1", since = "1.0.0")]
528pub use core::cmp;
529#[stable(feature = "rust1", since = "1.0.0")]
530pub use core::convert;
531#[stable(feature = "rust1", since = "1.0.0")]
532pub use core::default;
533#[unstable(feature = "field_projections", issue = "145383")]
534pub use core::field;
535#[stable(feature = "futures_api", since = "1.36.0")]
536pub use core::future;
537#[stable(feature = "core_hint", since = "1.27.0")]
538pub use core::hint;
539#[stable(feature = "rust1", since = "1.0.0")]
540#[allow(deprecated, clippy::legacy_numeric_constants)]
541pub use core::i8;
542#[stable(feature = "rust1", since = "1.0.0")]
543#[allow(deprecated, clippy::legacy_numeric_constants)]
544pub use core::i16;
545#[stable(feature = "rust1", since = "1.0.0")]
546#[allow(deprecated, clippy::legacy_numeric_constants)]
547pub use core::i32;
548#[stable(feature = "rust1", since = "1.0.0")]
549#[allow(deprecated, clippy::legacy_numeric_constants)]
550pub use core::i64;
551#[stable(feature = "i128", since = "1.26.0")]
552#[allow(deprecated, clippy::legacy_numeric_constants)]
553pub use core::i128;
554#[stable(feature = "rust1", since = "1.0.0")]
555pub use core::intrinsics;
556#[stable(feature = "rust1", since = "1.0.0")]
557#[allow(deprecated, clippy::legacy_numeric_constants)]
558pub use core::isize;
559#[stable(feature = "rust1", since = "1.0.0")]
560pub use core::iter;
561#[stable(feature = "rust1", since = "1.0.0")]
562pub use core::marker;
563#[stable(feature = "rust1", since = "1.0.0")]
564pub use core::mem;
565#[stable(feature = "rust1", since = "1.0.0")]
566pub use core::ops;
567#[stable(feature = "rust1", since = "1.0.0")]
568pub use core::option;
569#[stable(feature = "pin", since = "1.33.0")]
570pub use core::pin;
571#[stable(feature = "rust1", since = "1.0.0")]
572pub use core::ptr;
573#[stable(feature = "new_range_api", since = "1.96.0")]
574pub use core::range;
575#[stable(feature = "rust1", since = "1.0.0")]
576pub use core::result;
577#[stable(feature = "rust1", since = "1.0.0")]
578#[allow(deprecated, clippy::legacy_numeric_constants)]
579pub use core::u8;
580#[stable(feature = "rust1", since = "1.0.0")]
581#[allow(deprecated, clippy::legacy_numeric_constants)]
582pub use core::u16;
583#[stable(feature = "rust1", since = "1.0.0")]
584#[allow(deprecated, clippy::legacy_numeric_constants)]
585pub use core::u32;
586#[stable(feature = "rust1", since = "1.0.0")]
587#[allow(deprecated, clippy::legacy_numeric_constants)]
588pub use core::u64;
589#[stable(feature = "i128", since = "1.26.0")]
590#[allow(deprecated, clippy::legacy_numeric_constants)]
591pub use core::u128;
592#[unstable(feature = "unsafe_binders", issue = "130516")]
593pub use core::unsafe_binder;
594#[stable(feature = "rust1", since = "1.0.0")]
595#[allow(deprecated, clippy::legacy_numeric_constants)]
596pub use core::usize;
597
598#[stable(feature = "rust1", since = "1.0.0")]
599pub use alloc_crate::borrow;
600#[stable(feature = "rust1", since = "1.0.0")]
601pub use alloc_crate::boxed;
602#[stable(feature = "rust1", since = "1.0.0")]
603pub use alloc_crate::fmt;
604#[stable(feature = "rust1", since = "1.0.0")]
605pub use alloc_crate::format;
606#[stable(feature = "rust1", since = "1.0.0")]
607pub use alloc_crate::rc;
608#[stable(feature = "rust1", since = "1.0.0")]
609pub use alloc_crate::slice;
610#[stable(feature = "rust1", since = "1.0.0")]
611pub use alloc_crate::str;
612#[stable(feature = "rust1", since = "1.0.0")]
613pub use alloc_crate::string;
614#[stable(feature = "rust1", since = "1.0.0")]
615pub use alloc_crate::vec;
616
617#[path = "num/f128.rs"]
618pub mod f128;
619#[path = "num/f16.rs"]
620pub mod f16;
621#[path = "num/f32.rs"]
622pub mod f32;
623#[path = "num/f64.rs"]
624pub mod f64;
625
626#[macro_use]
627pub mod thread;
628pub mod ascii;
629pub mod backtrace;
630#[unstable(feature = "byte_str", issue = "134915")]
631pub mod byte_str;
632pub mod collections;
633pub mod env;
634pub mod error;
635pub mod ffi;
636pub mod fs;
637pub mod hash;
638pub mod io;
639pub mod net;
640pub mod num;
641#[allow(unreachable_pub)]
642pub mod os;
643pub mod panic;
644#[unstable(feature = "pattern_type_macro", issue = "123646")]
645pub mod pat;
646pub mod path;
647pub mod process;
648#[unstable(feature = "random", issue = "130703")]
649pub mod random;
650pub mod sync;
651pub mod time;
652#[unstable(feature = "view_type_macro", issue = "155938")]
653pub mod view;
654
655// Pull in `std_float` crate  into std. The contents of
656// `std_float` are in a different repository: rust-lang/portable-simd.
657#[path = "../../portable-simd/crates/std_float/src/lib.rs"]
658#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
659#[allow(rustdoc::bare_urls)]
660#[unstable(feature = "portable_simd", issue = "86656")]
661mod std_float;
662
663#[unstable(feature = "portable_simd", issue = "86656")]
664pub mod simd {
665    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
666
667    #[doc(inline)]
668    pub use core::simd::*;
669
670    #[doc(inline)]
671    pub use crate::std_float::StdFloat;
672}
673
674#[unstable(feature = "autodiff", issue = "124509")]
675#[doc = include_str!("../../core/src/autodiff.md")]
676pub mod autodiff {
677    /// This macro handles automatic differentiation.
678    pub use core::autodiff::{autodiff_forward, autodiff_reverse};
679}
680
681#[unstable(feature = "gpu_offload", issue = "131513")]
682#[doc = include_str!("../../core/src/offload.md")]
683pub mod offload {
684    pub use core::offload::{offload, offload_kernel};
685}
686
687#[stable(feature = "futures_api", since = "1.36.0")]
688pub mod task {
689    //! Types and Traits for working with asynchronous tasks.
690
691    #[doc(inline)]
692    #[stable(feature = "wake_trait", since = "1.51.0")]
693    pub use alloc::task::*;
694    #[doc(inline)]
695    #[stable(feature = "futures_api", since = "1.36.0")]
696    pub use core::task::*;
697}
698
699#[doc = include_str!("../../stdarch/crates/core_arch/src/core_arch_docs.md")]
700#[stable(feature = "simd_arch", since = "1.27.0")]
701pub mod arch {
702    #[stable(feature = "simd_arch", since = "1.27.0")]
703    // The `no_inline`-attribute is required to make the documentation of all
704    // targets available.
705    // See https://github.com/rust-lang/rust/pull/57808#issuecomment-457390549 for
706    // more information.
707    #[doc(no_inline)] // Note (#82861): required for correct documentation
708    pub use core::arch::*;
709
710    #[stable(feature = "simd_aarch64", since = "1.60.0")]
711    pub use std_detect::is_aarch64_feature_detected;
712    #[unstable(feature = "stdarch_arm_feature_detection", issue = "111190")]
713    pub use std_detect::is_arm_feature_detected;
714    #[stable(feature = "stdarch_loongarch_feature", since = "1.89.0")]
715    pub use std_detect::is_loongarch_feature_detected;
716    #[unstable(feature = "stdarch_powerpc_feature_detection", issue = "111191")]
717    pub use std_detect::is_powerpc_feature_detected;
718    #[stable(feature = "riscv_ratified", since = "1.78.0")]
719    pub use std_detect::is_riscv_feature_detected;
720    #[stable(feature = "stdarch_s390x_feature_detection", since = "1.93.0")]
721    pub use std_detect::is_s390x_feature_detected;
722    #[stable(feature = "simd_x86", since = "1.27.0")]
723    pub use std_detect::is_x86_feature_detected;
724    #[unstable(feature = "stdarch_mips_feature_detection", issue = "111188")]
725    pub use std_detect::{is_mips_feature_detected, is_mips64_feature_detected};
726}
727
728// This was stabilized in the crate root so we have to keep it there.
729#[stable(feature = "simd_x86", since = "1.27.0")]
730pub use std_detect::is_x86_feature_detected;
731
732#[allow(unreachable_pub)]
733mod sys;
734
735pub mod alloc;
736
737// Private support modules
738mod panicking;
739
740#[path = "../../backtrace/src/lib.rs"]
741#[allow(implicit_provenance_casts, unsafe_op_in_unsafe_fn)]
742#[allow(clippy::len_zero, clippy::needless_borrow, clippy::filter_map_next)] // FIXME
743mod backtrace_rs;
744
745#[stable(feature = "cfg_select", since = "1.95.0")]
746pub use core::cfg_select;
747#[unstable(
748    feature = "concat_bytes",
749    issue = "87555",
750    reason = "`concat_bytes` is not stable enough for use and is subject to change"
751)]
752pub use core::concat_bytes;
753#[allow(clippy::useless_attribute)]
754#[expect(
755    ineffective_unstable_reexports,
756    reason = "accepted as stable after accidental stabilization in 1.96, see #154645"
757)]
758#[unstable(feature = "derive_macro_global_path", issue = "154645")]
759pub use core::derive;
760#[unstable(feature = "gca_min_const_items", issue = "132980", implied_by = "gca_adts")]
761pub use core::gca;
762#[stable(feature = "matches_macro", since = "1.42.0")]
763pub use core::matches;
764#[stable(feature = "core_primitive", since = "1.43.0")]
765pub use core::primitive;
766#[stable(feature = "todo_macro", since = "1.40.0")]
767pub use core::todo;
768// Re-export built-in macros defined through core.
769#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
770pub use core::{
771    assert, cfg, column, compile_error, concat, const_format_args, env, file, format_args,
772    format_args_nl, include, include_bytes, include_str, line, log_syntax, module_path, option_env,
773    stringify, trace_macros,
774};
775// Re-export macros defined in core.
776#[stable(feature = "rust1", since = "1.0.0")]
777#[expect(deprecated, reason = "`try! macro")]
778pub use core::{
779    assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, r#try, unimplemented,
780    unreachable, write, writeln,
781};
782#[stable(feature = "assert_matches", since = "1.96.0")]
783pub use core::{assert_matches, debug_assert_matches};
784
785// Re-export unstable derive macro defined through core.
786#[unstable(feature = "derive_from", issue = "144889")]
787/// Unstable module containing the unstable `From` derive macro.
788pub mod from {
789    #[unstable(feature = "derive_from", issue = "144889")]
790    pub use core::from::From;
791}
792
793// We include the following files here *again* (they are already included in libcore)
794// so that they show up in search results for the std crate, and to avoid breaking
795// existing links:
796
797// documentation for built-in attributes. Using `include!` because rustdoc
798// only looks for these modules at the crate level.
799include!("../../core/src/attribute_docs.rs");
800
801// Include a number of private modules that exist solely to provide
802// the rustdoc documentation for the existing keywords. Using `include!`
803// because rustdoc only looks for these modules at the crate level.
804include!("../../core/src/keyword_docs.rs");
805
806// Include a number of private modules that exist solely to provide
807// the rustdoc documentation for primitive types. Using `include!`
808// because rustdoc only looks for these modules at the crate level.
809include!("../../core/src/primitive_docs.rs");
810
811// This is required to avoid an unstable error when `restricted-std` is not
812// enabled. The use of #![feature(restricted_std)] in rustc-std-workspace-std
813// is unconditional, so the unstable feature needs to be defined somewhere.
814#[unstable(feature = "restricted_std", issue = "none")]
815mod __restricted_std_workaround {}
816
817#[cfg(test)]
818#[allow(dead_code)] // Not used in all configurations.
819pub(crate) mod test_helpers;