lib.rs - source
Description: Source of the Rust file `library/std/src/lib.rs`.

#
std/
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][rust-zulip]
    98//! #docs.
    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//! [rust-zulip]: https://rust-lang.zulipchat.com/
    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(missing_debug_implementations)]
    245#![allow(explicit_outlives_requirements)]
    246#![allow(unused_lifetimes)]
    247#![allow(internal_features)]
    248#![deny(fuzzy_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(test, feature(internal_output_capture, print_internals, update_panic_count, rt))]
    259#![cfg_attr(
    260    all(target_vendor = "fortanix", target_env = "sgx"),
    261    feature(slice_index_methods, coerce_unsized, sgx_platform)
    262)]
    263#![cfg_attr(target_family = "wasm", feature(stdarch_wasm_atomic_wait))]
    264#![cfg_attr(target_arch = "wasm64", feature(simd_wasm64))]
    265//
    266// Language features:
    267// tidy-alphabetical-start
    268#![feature(alloc_error_handler)]
    269#![feature(allocator_internals)]
    270#![feature(allow_internal_unsafe)]
    271#![feature(allow_internal_unstable)]
    272#![feature(asm_experimental_arch)]
    273#![feature(autodiff)]
    274#![feature(cfg_sanitizer_cfi)]
    275#![feature(cfg_target_thread_local)]
    276#![feature(cfi_encoding)]
    277#![feature(const_default)]
    278#![feature(const_trait_impl)]
    279#![feature(core_float_math)]
    280#![feature(decl_macro)]
    281#![feature(deprecated_suggestion)]
    282#![feature(doc_cfg)]
    283#![feature(doc_masked)]
    284#![feature(doc_notable_trait)]
    285#![feature(dropck_eyepatch)]
    286#![feature(f16)]
    287#![feature(f128)]
    288#![feature(ffi_const)]
    289#![feature(formatting_options)]
    290#![feature(funnel_shifts)]
    291#![feature(if_let_guard)]
    292#![feature(intra_doc_pointers)]
    293#![feature(iter_advance_by)]
    294#![feature(iter_next_chunk)]
    295#![feature(lang_items)]
    296#![feature(link_cfg)]
    297#![feature(linkage)]
    298#![feature(macro_metavar_expr_concat)]
    299#![feature(maybe_uninit_fill)]
    300#![feature(min_specialization)]
    301#![feature(must_not_suspend)]
    302#![feature(needs_panic_runtime)]
    303#![feature(negative_impls)]
    304#![feature(never_type)]
    305#![feature(optimize_attribute)]
    306#![feature(prelude_import)]
    307#![feature(rustc_attrs)]
    308#![feature(rustdoc_internals)]
    309#![feature(staged_api)]
    310#![feature(stmt_expr_attributes)]
    311#![feature(strict_provenance_lints)]
    312#![feature(thread_local)]
    313#![feature(try_blocks)]
    314#![feature(try_trait_v2)]
    315#![feature(type_alias_impl_trait)]
    316// tidy-alphabetical-end
    317//
    318// Library features (core):
    319// tidy-alphabetical-start
    320#![feature(bstr)]
    321#![feature(bstr_internals)]
    322#![feature(cast_maybe_uninit)]
    323#![feature(cfg_select)]
    324#![feature(char_internals)]
    325#![feature(clone_to_uninit)]
    326#![feature(const_convert)]
    327#![feature(core_intrinsics)]
    328#![feature(core_io_borrowed_buf)]
    329#![feature(drop_guard)]
    330#![feature(duration_constants)]
    331#![feature(error_generic_member_access)]
    332#![feature(error_iter)]
    333#![feature(exact_size_is_empty)]
    334#![feature(exclusive_wrapper)]
    335#![feature(extend_one)]
    336#![feature(float_algebraic)]
    337#![feature(float_gamma)]
    338#![feature(float_minimum_maximum)]
    339#![feature(fmt_internals)]
    340#![feature(fn_ptr_trait)]
    341#![feature(generic_atomic)]
    342#![feature(hasher_prefixfree_extras)]
    343#![feature(hashmap_internals)]
    344#![feature(hint_must_use)]
    345#![feature(int_from_ascii)]
    346#![feature(ip)]
    347#![feature(maybe_uninit_array_assume_init)]
    348#![feature(panic_can_unwind)]
    349#![feature(panic_internals)]
    350#![feature(pin_coerce_unsized_trait)]
    351#![feature(pointer_is_aligned_to)]
    352#![feature(portable_simd)]
    353#![feature(ptr_as_uninit)]
    354#![feature(ptr_mask)]
    355#![feature(random)]
    356#![feature(slice_internals)]
    357#![feature(slice_ptr_get)]
    358#![feature(slice_range)]
    359#![feature(slice_split_once)]
    360#![feature(std_internals)]
    361#![feature(str_internals)]
    362#![feature(sync_unsafe_cell)]
    363#![feature(temporary_niche_types)]
    364#![feature(ub_checks)]
    365#![feature(used_with_arg)]
    366// tidy-alphabetical-end
    367//
    368// Library features (alloc):
    369// tidy-alphabetical-start
    370#![feature(alloc_layout_extra)]
    371#![feature(allocator_api)]
    372#![feature(clone_from_ref)]
    373#![feature(get_mut_unchecked)]
    374#![feature(map_try_insert)]
    375#![feature(slice_concat_trait)]
    376#![feature(thin_box)]
    377#![feature(try_reserve_kind)]
    378#![feature(try_with_capacity)]
    379#![feature(unique_rc_arc)]
    380#![feature(wtf8_internals)]
    381// tidy-alphabetical-end
    382//
    383// Library features (unwind):
    384// tidy-alphabetical-start
    385#![feature(panic_unwind)]
    386// tidy-alphabetical-end
    387//
    388// Library features (std_detect):
    389// tidy-alphabetical-start
    390#![feature(stdarch_internal)]
    391// tidy-alphabetical-end
    392//
    393// Only for re-exporting:
    394// tidy-alphabetical-start
    395#![feature(assert_matches)]
    396#![feature(async_iterator)]
    397#![feature(c_variadic)]
    398#![feature(cfg_accessible)]
    399#![feature(cfg_eval)]
    400#![feature(concat_bytes)]
    401#![feature(const_format_args)]
    402#![feature(custom_test_frameworks)]
    403#![feature(edition_panic)]
    404#![feature(format_args_nl)]
    405#![feature(log_syntax)]
    406#![feature(test)]
    407#![feature(trace_macros)]
    408// tidy-alphabetical-end
    409//
    410// Only used in tests/benchmarks:
    411//
    412// Only for const-ness:
    413// tidy-alphabetical-start
    414#![feature(io_const_error)]
    415// tidy-alphabetical-end
    416//
    417#![default_lib_allocator]
    418
    419// The Rust prelude
    420// The compiler expects the prelude definition to be defined before its use statement.
    421pub mod prelude;
    422
    423// Explicitly import the prelude. The compiler uses this same unstable attribute
    424// to import the prelude implicitly when building crates that depend on std.
    425#[prelude_import]
    426#[allow(unused)]
    427use prelude::rust_2024::*;
    428
    429// Access to Bencher, etc.
    430#[cfg(test)]
    431extern crate test;
    432
    433#[allow(unused_imports)] // macros from `alloc` are not used on all platforms
    434#[macro_use]
    435extern crate alloc as alloc_crate;
    436
    437// Many compiler tests depend on libc being pulled in by std
    438// so include it here even if it's unused.
    439#[doc(masked)]
    440#[allow(unused_extern_crates)]
    441#[cfg(not(all(windows, target_env = "msvc")))]
    442extern crate libc;
    443
    444// We always need an unwinder currently for backtraces
    445#[doc(masked)]
    446#[allow(unused_extern_crates)]
    447extern crate unwind;
    448
    449// FIXME: #94122 this extern crate definition only exist here to stop
    450// miniz_oxide docs leaking into std docs. Find better way to do it.
    451// Remove exclusion from tidy platform check when this removed.
    452#[doc(masked)]
    453#[allow(unused_extern_crates)]
    454#[cfg(all(
    455    not(all(windows, target_env = "msvc", not(target_vendor = "uwp"))),
    456    feature = "miniz_oxide"
    457))]
    458extern crate miniz_oxide;
    459
    460// During testing, this crate is not actually the "real" std library, but rather
    461// it links to the real std library, which was compiled from this same source
    462// code. So any lang items std defines are conditionally excluded (or else they
    463// would generate duplicate lang item errors), and any globals it defines are
    464// _not_ the globals used by "real" std. So this import, defined only during
    465// testing gives test-std access to real-std lang items and globals. See #2912
    466#[cfg(test)]
    467extern crate std as realstd;
    468
    469// The standard macros that are not built-in to the compiler.
    470#[macro_use]
    471mod macros;
    472
    473// The runtime entry point and a few unstable public functions used by the
    474// compiler
    475#[macro_use]
    476pub mod rt;
    477
    478#[stable(feature = "rust1", since = "1.0.0")]
    479pub use core::any;
    480#[stable(feature = "core_array", since = "1.35.0")]
    481pub use core::array;
    482#[unstable(feature = "async_iterator", issue = "79024")]
    483pub use core::async_iter;
    484#[stable(feature = "rust1", since = "1.0.0")]
    485pub use core::cell;
    486#[stable(feature = "rust1", since = "1.0.0")]
    487pub use core::char;
    488#[stable(feature = "rust1", since = "1.0.0")]
    489pub use core::clone;
    490#[stable(feature = "rust1", since = "1.0.0")]
    491pub use core::cmp;
    492#[stable(feature = "rust1", since = "1.0.0")]
    493pub use core::convert;
    494#[stable(feature = "rust1", since = "1.0.0")]
    495pub use core::default;
    496#[stable(feature = "futures_api", since = "1.36.0")]
    497pub use core::future;
    498#[stable(feature = "core_hint", since = "1.27.0")]
    499pub use core::hint;
    500#[stable(feature = "rust1", since = "1.0.0")]
    501#[allow(deprecated, deprecated_in_future)]
    502pub use core::i8;
    503#[stable(feature = "rust1", since = "1.0.0")]
    504#[allow(deprecated, deprecated_in_future)]
    505pub use core::i16;
    506#[stable(feature = "rust1", since = "1.0.0")]
    507#[allow(deprecated, deprecated_in_future)]
    508pub use core::i32;
    509#[stable(feature = "rust1", since = "1.0.0")]
    510#[allow(deprecated, deprecated_in_future)]
    511pub use core::i64;
    512#[stable(feature = "i128", since = "1.26.0")]
    513#[allow(deprecated, deprecated_in_future)]
    514pub use core::i128;
    515#[stable(feature = "rust1", since = "1.0.0")]
    516pub use core::intrinsics;
    517#[stable(feature = "rust1", since = "1.0.0")]
    518#[allow(deprecated, deprecated_in_future)]
    519pub use core::isize;
    520#[stable(feature = "rust1", since = "1.0.0")]
    521pub use core::iter;
    522#[stable(feature = "rust1", since = "1.0.0")]
    523pub use core::marker;
    524#[stable(feature = "rust1", since = "1.0.0")]
    525pub use core::mem;
    526#[stable(feature = "rust1", since = "1.0.0")]
    527pub use core::ops;
    528#[stable(feature = "rust1", since = "1.0.0")]
    529pub use core::option;
    530#[stable(feature = "pin", since = "1.33.0")]
    531pub use core::pin;
    532#[stable(feature = "rust1", since = "1.0.0")]
    533pub use core::ptr;
    534#[unstable(feature = "new_range_api", issue = "125687")]
    535pub use core::range;
    536#[stable(feature = "rust1", since = "1.0.0")]
    537pub use core::result;
    538#[stable(feature = "rust1", since = "1.0.0")]
    539#[allow(deprecated, deprecated_in_future)]
    540pub use core::u8;
    541#[stable(feature = "rust1", since = "1.0.0")]
    542#[allow(deprecated, deprecated_in_future)]
    543pub use core::u16;
    544#[stable(feature = "rust1", since = "1.0.0")]
    545#[allow(deprecated, deprecated_in_future)]
    546pub use core::u32;
    547#[stable(feature = "rust1", since = "1.0.0")]
    548#[allow(deprecated, deprecated_in_future)]
    549pub use core::u64;
    550#[stable(feature = "i128", since = "1.26.0")]
    551#[allow(deprecated, deprecated_in_future)]
    552pub use core::u128;
    553#[unstable(feature = "unsafe_binders", issue = "130516")]
    554pub use core::unsafe_binder;
    555#[stable(feature = "rust1", since = "1.0.0")]
    556#[allow(deprecated, deprecated_in_future)]
    557pub use core::usize;
    558
    559#[stable(feature = "rust1", since = "1.0.0")]
    560pub use alloc_crate::borrow;
    561#[stable(feature = "rust1", since = "1.0.0")]
    562pub use alloc_crate::boxed;
    563#[stable(feature = "rust1", since = "1.0.0")]
    564pub use alloc_crate::fmt;
    565#[stable(feature = "rust1", since = "1.0.0")]
    566pub use alloc_crate::format;
    567#[stable(feature = "rust1", since = "1.0.0")]
    568pub use alloc_crate::rc;
    569#[stable(feature = "rust1", since = "1.0.0")]
    570pub use alloc_crate::slice;
    571#[stable(feature = "rust1", since = "1.0.0")]
    572pub use alloc_crate::str;
    573#[stable(feature = "rust1", since = "1.0.0")]
    574pub use alloc_crate::string;
    575#[stable(feature = "rust1", since = "1.0.0")]
    576pub use alloc_crate::vec;
    577
    578#[path = "num/f128.rs"]
    579pub mod f128;
    580#[path = "num/f16.rs"]
    581pub mod f16;
    582#[path = "num/f32.rs"]
    583pub mod f32;
    584#[path = "num/f64.rs"]
    585pub mod f64;
    586
    587#[macro_use]
    588pub mod thread;
    589pub mod ascii;
    590pub mod backtrace;
    591#[unstable(feature = "bstr", issue = "134915")]
    592pub mod bstr;
    593pub mod collections;
    594pub mod env;
    595pub mod error;
    596pub mod ffi;
    597pub mod fs;
    598pub mod hash;
    599pub mod io;
    600pub mod net;
    601pub mod num;
    602pub mod os;
    603pub mod panic;
    604#[unstable(feature = "pattern_type_macro", issue = "123646")]
    605pub mod pat;
    606pub mod path;
    607pub mod process;
    608#[unstable(feature = "random", issue = "130703")]
    609pub mod random;
    610pub mod sync;
    611pub mod time;
    612
    613// Pull in `std_float` crate  into std. The contents of
    614// `std_float` are in a different repository: rust-lang/portable-simd.
    615#[path = "../../portable-simd/crates/std_float/src/lib.rs"]
    616#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
    617#[allow(rustdoc::bare_urls)]
    618#[unstable(feature = "portable_simd", issue = "86656")]
    619mod std_float;
    620
    621#[unstable(feature = "portable_simd", issue = "86656")]
    622pub mod simd {
    623    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
    624
    625    #[doc(inline)]
    626    pub use core::simd::*;
    627
    628    #[doc(inline)]
    629    pub use crate::std_float::StdFloat;
    630}
    631
    632#[unstable(feature = "autodiff", issue = "124509")]
    633/// This module provides support for automatic differentiation.
    634pub mod autodiff {
    635    /// This macro handles automatic differentiation.
    636    pub use core::autodiff::{autodiff_forward, autodiff_reverse};
    637}
    638
    639#[stable(feature = "futures_api", since = "1.36.0")]
    640pub mod task {
    641    //! Types and Traits for working with asynchronous tasks.
    642
    643    #[doc(inline)]
    644    #[stable(feature = "wake_trait", since = "1.51.0")]
    645    pub use alloc::task::*;
    646    #[doc(inline)]
    647    #[stable(feature = "futures_api", since = "1.36.0")]
    648    pub use core::task::*;
    649}
    650
    651#[doc = include_str!("../../stdarch/crates/core_arch/src/core_arch_docs.md")]
    652#[stable(feature = "simd_arch", since = "1.27.0")]
    653pub mod arch {
    654    #[stable(feature = "simd_arch", since = "1.27.0")]
    655    // The `no_inline`-attribute is required to make the documentation of all
    656    // targets available.
    657    // See https://github.com/rust-lang/rust/pull/57808#issuecomment-457390549 for
    658    // more information.
    659    #[doc(no_inline)] // Note (#82861): required for correct documentation
    660    pub use core::arch::*;
    661
    662    #[stable(feature = "simd_aarch64", since = "1.60.0")]
    663    pub use std_detect::is_aarch64_feature_detected;
    664    #[unstable(feature = "stdarch_arm_feature_detection", issue = "111190")]
    665    pub use std_detect::is_arm_feature_detected;
    666    #[unstable(feature = "is_loongarch_feature_detected", issue = "117425")]
    667    pub use std_detect::is_loongarch_feature_detected;
    668    #[unstable(feature = "is_riscv_feature_detected", issue = "111192")]
    669    pub use std_detect::is_riscv_feature_detected;
    670    #[stable(feature = "stdarch_s390x_feature_detection", since = "1.93.0")]
    671    pub use std_detect::is_s390x_feature_detected;
    672    #[stable(feature = "simd_x86", since = "1.27.0")]
    673    pub use std_detect::is_x86_feature_detected;
    674    #[unstable(feature = "stdarch_mips_feature_detection", issue = "111188")]
    675    pub use std_detect::{is_mips_feature_detected, is_mips64_feature_detected};
    676    #[unstable(feature = "stdarch_powerpc_feature_detection", issue = "111191")]
    677    pub use std_detect::{is_powerpc_feature_detected, is_powerpc64_feature_detected};
    678}
    679
    680// This was stabilized in the crate root so we have to keep it there.
    681#[stable(feature = "simd_x86", since = "1.27.0")]
    682pub use std_detect::is_x86_feature_detected;
    683
    684mod sys;
    685
    686pub mod alloc;
    687
    688// Private support modules
    689mod panicking;
    690
    691#[path = "../../backtrace/src/lib.rs"]
    692#[allow(dead_code, unused_attributes, fuzzy_provenance_casts, unsafe_op_in_unsafe_fn)]
    693mod backtrace_rs;
    694
    695#[unstable(feature = "cfg_select", issue = "115585")]
    696pub use core::cfg_select;
    697#[unstable(
    698    feature = "concat_bytes",
    699    issue = "87555",
    700    reason = "`concat_bytes` is not stable enough for use and is subject to change"
    701)]
    702pub use core::concat_bytes;
    703#[stable(feature = "matches_macro", since = "1.42.0")]
    704#[allow(deprecated, deprecated_in_future)]
    705pub use core::matches;
    706#[stable(feature = "core_primitive", since = "1.43.0")]
    707pub use core::primitive;
    708#[stable(feature = "todo_macro", since = "1.40.0")]
    709#[allow(deprecated, deprecated_in_future)]
    710pub use core::todo;
    711// Re-export built-in macros defined through core.
    712#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
    713pub use core::{
    714    assert, assert_matches, cfg, column, compile_error, concat, const_format_args, env, file,
    715    format_args, format_args_nl, include, include_bytes, include_str, line, log_syntax,
    716    module_path, option_env, stringify, trace_macros,
    717};
    718// Re-export macros defined in core.
    719#[stable(feature = "rust1", since = "1.0.0")]
    720#[allow(deprecated, deprecated_in_future)]
    721pub use core::{
    722    assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, r#try, unimplemented,
    723    unreachable, write, writeln,
    724};
    725
    726// Re-export unstable derive macro defined through core.
    727#[unstable(feature = "derive_from", issue = "144889")]
    728/// Unstable module containing the unstable `From` derive macro.
    729pub mod from {
    730    #[unstable(feature = "derive_from", issue = "144889")]
    731    pub use core::from::From;
    732}
    733
    734// Include a number of private modules that exist solely to provide
    735// the rustdoc documentation for primitive types. Using `include!`
    736// because rustdoc only looks for these modules at the crate level.
    737include!("../../core/src/primitive_docs.rs");
    738
    739// Include a number of private modules that exist solely to provide
    740// the rustdoc documentation for the existing keywords. Using `include!`
    741// because rustdoc only looks for these modules at the crate level.
    742include!("keyword_docs.rs");
    743
    744// This is required to avoid an unstable error when `restricted-std` is not
    745// enabled. The use of #![feature(restricted_std)] in rustc-std-workspace-std
    746// is unconditional, so the unstable feature needs to be defined somewhere.
    747#[unstable(feature = "restricted_std", issue = "none")]
    748mod __restricted_std_workaround {}
    749
    750mod sealed {
    751    /// This trait being unreachable from outside the crate
    752    /// prevents outside implementations of our extension traits.
    753    /// This allows adding more trait methods in the future.
    754    #[unstable(feature = "sealed", issue = "none")]
    755    pub trait Sealed {}
    756}
    757
    758#[cfg(test)]
    759#[allow(dead_code)] // Not used in all configurations.
    760pub(crate) mod test_helpers;