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core/
lib.rs

1//! # The Rust Core Library
2//!
3//! The Rust Core Library is the dependency-free[^free] foundation of [The
4//! Rust Standard Library](../std/index.html). It is the portable glue
5//! between the language and its libraries, defining the intrinsic and
6//! primitive building blocks of all Rust code. It links to no
7//! upstream libraries, no system libraries, and no libc.
8//!
9//! [^free]: Strictly speaking, there are some symbols which are needed but
10//!          they aren't always necessary.
11//!
12//! The core library is *minimal*: it isn't even aware of heap allocation,
13//! nor does it provide concurrency or I/O. These things require
14//! platform integration, and this library is platform-agnostic.
15//!
16//! # How to use the core library
17//!
18//! Please note that all of these details are currently not considered stable.
19//!
20// FIXME: Fill me in with more detail when the interface settles
21//! This library is built on the assumption of a few existing symbols:
22//!
23//! * `memcpy`, `memmove`, `memset`, `memcmp`, `bcmp`, `strlen` - These are core memory routines
24//!   which are generated by Rust codegen backends. Additionally, this library can make explicit
25//!   calls to `strlen`. Their signatures are the same as found in C, but there are extra
26//!   assumptions about their semantics: For `memcpy`, `memmove`, `memset`, `memcmp`, and `bcmp`, if
27//!   the `n` parameter is 0, the function is assumed to not be UB, even if the pointers are NULL or
28//!   dangling. (Note that making extra assumptions about these functions is common among compilers:
29//!   [clang](https://reviews.llvm.org/D86993) and [GCC](https://gcc.gnu.org/onlinedocs/gcc/Standards.html#C-Language) do the same.)
30//!   These functions are often provided by the system libc, but can also be provided by the
31//!   [compiler-builtins crate](https://crates.io/crates/compiler_builtins).
32//!   Note that the library does not guarantee that it will always make these assumptions, so Rust
33//!   user code directly calling the C functions should follow the C specification! The advice for
34//!   Rust user code is to call the functions provided by this library instead (such as
35//!   `ptr::copy`).
36//!
37//! * Panic handler - This function takes one argument, a `&panic::PanicInfo`. It is up to consumers of this core
38//!   library to define this panic function; it is only required to never
39//!   return. You should mark your implementation using `#[panic_handler]`.
40//!
41//! * `rust_eh_personality` - is used by the failure mechanisms of the
42//!   compiler. This is often mapped to GCC's personality function, but crates
43//!   which do not trigger a panic can be assured that this function is never
44//!   called. The `lang` attribute is called `eh_personality`.
45
46#![stable(feature = "core", since = "1.6.0")]
47#![doc(
48    html_playground_url = "https://play.rust-lang.org/",
49    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
50    test(no_crate_inject, attr(deny(warnings))),
51    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
52)]
53#![doc(rust_logo)]
54#![doc(auto_cfg(hide(
55    no_fp_fmt_parse,
56    target_pointer_width = "16",
57    target_pointer_width = "32",
58    target_pointer_width = "64",
59    target_has_atomic = "8",
60    target_has_atomic = "16",
61    target_has_atomic = "32",
62    target_has_atomic = "64",
63    target_has_atomic = "ptr",
64    target_has_atomic_equal_alignment = "8",
65    target_has_atomic_equal_alignment = "16",
66    target_has_atomic_equal_alignment = "32",
67    target_has_atomic_equal_alignment = "64",
68    target_has_atomic_equal_alignment = "ptr",
69    target_has_atomic_load_store = "8",
70    target_has_atomic_load_store = "16",
71    target_has_atomic_load_store = "32",
72    target_has_atomic_load_store = "64",
73    target_has_atomic_load_store = "ptr",
74)))]
75#![no_core]
76#![rustc_coherence_is_core]
77#![rustc_preserve_ub_checks]
78//
79// Lints:
80#![deny(rust_2021_incompatible_or_patterns)]
81#![deny(unsafe_op_in_unsafe_fn)]
82#![deny(fuzzy_provenance_casts)]
83#![warn(deprecated_in_future)]
84#![warn(missing_debug_implementations)]
85#![warn(missing_docs)]
86#![allow(explicit_outlives_requirements)]
87#![allow(incomplete_features)]
88#![warn(multiple_supertrait_upcastable)]
89#![allow(internal_features)]
90#![allow(unused_features)]
91#![deny(ffi_unwind_calls)]
92#![warn(unreachable_pub)]
93// Do not check link redundancy on bootstrapping phase
94#![allow(rustdoc::redundant_explicit_links)]
95#![warn(rustdoc::unescaped_backticks)]
96//
97// Ferrocene addition: We removed the tidy directives for alphabetical ordering to reduce the number
98// of conflicts we have when merging main.
99//
100// Library features:
101// not-alphabetical-start
102#![cfg_attr(not(feature = "ferrocene_subset"), feature(asm_experimental_arch))]
103#![cfg_attr(not(feature = "ferrocene_subset"), feature(bstr_internals))]
104#![feature(cfg_select)]
105#![feature(cfg_target_has_reliable_f16_f128)]
106#![feature(const_carrying_mul_add)]
107#![feature(const_cmp)]
108#![feature(const_destruct)]
109#![feature(const_eval_select)]
110#![feature(const_select_unpredictable)]
111#![feature(core_intrinsics)]
112#![feature(coverage_attribute)]
113#![feature(disjoint_bitor)]
114#![feature(internal_impls_macro)]
115#![cfg_attr(not(feature = "ferrocene_subset"), feature(link_cfg))]
116#![cfg_attr(not(feature = "ferrocene_subset"), feature(offset_of_enum))]
117#![feature(panic_internals)]
118#![feature(pattern_type_macro)]
119#![feature(ub_checks)]
120// not-alphabetical-end
121//
122// Language features:
123// not-alphabetical-start
124#![feature(abi_unadjusted)]
125#![feature(adt_const_params)]
126#![feature(allow_internal_unsafe)]
127#![feature(allow_internal_unstable)]
128#![feature(auto_traits)]
129#![feature(cfg_sanitize)]
130#![feature(cfg_target_has_atomic)]
131#![feature(cfg_target_has_atomic_equal_alignment)]
132#![feature(cfg_ub_checks)]
133#![feature(const_precise_live_drops)]
134#![feature(const_trait_impl)]
135#![feature(decl_macro)]
136#![feature(deprecated_suggestion)]
137#![feature(derive_const)]
138#![feature(diagnostic_on_const)]
139#![feature(doc_cfg)]
140#![cfg_attr(not(feature = "ferrocene_subset"), feature(doc_notable_trait))]
141#![feature(extern_types)]
142#![feature(f128)]
143#![feature(f16)]
144#![feature(freeze_impls)]
145#![feature(fundamental)]
146#![feature(funnel_shifts)]
147#![feature(intra_doc_pointers)]
148#![feature(intrinsics)]
149#![feature(lang_items)]
150#![feature(link_llvm_intrinsics)]
151#![feature(macro_metavar_expr)]
152#![feature(macro_metavar_expr_concat)]
153#![feature(marker_trait_attr)]
154#![feature(min_specialization)]
155#![feature(multiple_supertrait_upcastable)]
156#![feature(must_not_suspend)]
157#![feature(negative_impls)]
158#![feature(never_type)]
159#![feature(no_core)]
160#![feature(optimize_attribute)]
161#![feature(pattern_types)]
162#![feature(prelude_import)]
163#![feature(repr_simd)]
164#![feature(rustc_attrs)]
165#![feature(rustdoc_internals)]
166#![feature(simd_ffi)]
167#![feature(staged_api)]
168#![feature(stmt_expr_attributes)]
169#![feature(strict_provenance_lints)]
170#![feature(target_feature_inline_always)]
171#![feature(trait_alias)]
172#![feature(transparent_unions)]
173#![feature(try_blocks)]
174#![feature(uint_carryless_mul)]
175#![feature(unboxed_closures)]
176#![feature(unsized_fn_params)]
177#![cfg_attr(not(feature = "ferrocene_subset"), feature(with_negative_coherence))]
178// not-alphabetical-end
179//
180// Target features:
181// not-alphabetical-start
182#![cfg_attr(not(feature = "ferrocene_subset"), feature(aarch64_unstable_target_feature))]
183#![feature(arm_target_feature)]
184#![cfg_attr(not(feature = "ferrocene_subset"), feature(avx10_target_feature))]
185#![cfg_attr(not(feature = "ferrocene_subset"), feature(hexagon_target_feature))]
186#![cfg_attr(not(feature = "ferrocene_subset"), feature(loongarch_target_feature))]
187#![cfg_attr(not(feature = "ferrocene_subset"), feature(mips_target_feature))]
188#![cfg_attr(not(feature = "ferrocene_subset"), feature(powerpc_target_feature))]
189#![cfg_attr(not(feature = "ferrocene_subset"), feature(nvptx_target_feature))]
190#![cfg_attr(not(feature = "ferrocene_subset"), feature(riscv_target_feature))]
191#![cfg_attr(not(feature = "ferrocene_subset"), feature(rtm_target_feature))]
192#![cfg_attr(not(feature = "ferrocene_subset"), feature(s390x_target_feature))]
193#![cfg_attr(not(feature = "ferrocene_subset"), feature(wasm_target_feature))]
194#![cfg_attr(not(feature = "ferrocene_subset"), feature(x86_amx_intrinsics))]
195// not-alphabetical-end
196//
197// Ferrocene lints/features:
198#![cfg_attr(
199    feature = "ferrocene_subset",
200    expect(rustdoc::broken_intra_doc_links),
201    expect(rustdoc::private_intra_doc_links)
202)]
203#![feature(register_tool)]
204#![register_tool(ferrocene)]
205#![doc(auto_cfg(hide(feature = "ferrocene_subset")))]
206
207// allow using `core::` in intra-doc links
208#[allow(unused_extern_crates)]
209extern crate self as core;
210
211/* The core prelude, not as all-encompassing as the std prelude */
212// The compiler expects the prelude definition to be defined before it's use statement.
213pub mod prelude;
214
215#[prelude_import]
216#[allow(unused)]
217use prelude::rust_2024::*;
218
219#[macro_use]
220mod macros;
221
222/// Ferrocene addition: Hidden module to test crate-internal functionality
223#[doc(hidden)]
224#[unstable(feature = "ferrocene_test", issue = "none")]
225#[cfg(not(feature = "ferrocene_subset"))]
226pub mod ferrocene_test;
227
228#[stable(feature = "assert_matches", since = "CURRENT_RUSTC_VERSION")]
229pub use crate::macros::{assert_matches, debug_assert_matches};
230
231#[unstable(feature = "derive_from", issue = "144889")]
232/// Unstable module containing the unstable `From` derive macro.
233pub mod from {
234    #[unstable(feature = "derive_from", issue = "144889")]
235    pub use crate::macros::builtin::From;
236}
237
238// We don't export this through #[macro_export] for now, to avoid breakage.
239#[unstable(feature = "autodiff", issue = "124509")]
240/// Unstable module containing the unstable `autodiff` macro.
241pub mod autodiff {
242    #[unstable(feature = "autodiff", issue = "124509")]
243    pub use crate::macros::builtin::{autodiff_forward, autodiff_reverse};
244}
245
246#[unstable(feature = "contracts", issue = "128044")]
247#[cfg(not(feature = "ferrocene_subset"))]
248pub mod contracts;
249
250#[unstable(feature = "cfg_select", issue = "115585")]
251pub use crate::macros::cfg_select;
252
253#[macro_use]
254mod internal_macros;
255
256#[path = "num/shells/legacy_int_modules.rs"]
257#[cfg(not(feature = "ferrocene_subset"))]
258mod legacy_int_modules;
259#[stable(feature = "rust1", since = "1.0.0")]
260#[allow(clippy::useless_attribute)] // FIXME false positive (https://github.com/rust-lang/rust-clippy/issues/15636)
261#[allow(deprecated_in_future)]
262#[cfg(not(feature = "ferrocene_subset"))]
263pub use legacy_int_modules::{i8, i16, i32, i64, isize, u8, u16, u32, u64, usize};
264#[stable(feature = "i128", since = "1.26.0")]
265#[allow(clippy::useless_attribute)] // FIXME false positive (https://github.com/rust-lang/rust-clippy/issues/15636)
266#[allow(deprecated_in_future)]
267#[cfg(not(feature = "ferrocene_subset"))]
268pub use legacy_int_modules::{i128, u128};
269
270#[path = "num/f128.rs"]
271#[cfg(not(feature = "ferrocene_subset"))]
272pub mod f128;
273#[path = "num/f16.rs"]
274pub mod f16;
275#[path = "num/f32.rs"]
276pub mod f32;
277#[path = "num/f64.rs"]
278pub mod f64;
279
280#[macro_use]
281pub mod num;
282
283/* Core modules for ownership management */
284
285pub mod hint;
286pub mod intrinsics;
287pub mod mem;
288#[unstable(feature = "profiling_marker_api", issue = "148197")]
289pub mod profiling;
290pub mod ptr;
291#[unstable(feature = "ub_checks", issue = "none")]
292pub mod ub_checks;
293
294/* Core language traits */
295
296pub mod borrow;
297pub mod clone;
298pub mod cmp;
299pub mod convert;
300pub mod default;
301#[cfg(not(feature = "ferrocene_subset"))]
302pub mod error;
303#[cfg(not(feature = "ferrocene_subset"))]
304pub mod index;
305pub mod marker;
306pub mod ops;
307
308/* Core types and methods on primitives */
309
310pub mod any;
311pub mod array;
312pub mod ascii;
313#[cfg(not(feature = "ferrocene_subset"))]
314pub mod asserting;
315#[unstable(feature = "async_iterator", issue = "79024")]
316#[cfg(not(feature = "ferrocene_subset"))]
317pub mod async_iter;
318#[unstable(feature = "bstr", issue = "134915")]
319pub mod bstr;
320pub mod cell;
321pub mod char;
322pub mod ffi;
323#[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
324#[cfg(not(feature = "ferrocene_subset"))]
325pub mod io;
326pub mod iter;
327#[cfg(not(feature = "ferrocene_subset"))]
328pub mod net;
329pub mod option;
330#[cfg(not(feature = "ferrocene_subset"))]
331pub mod os;
332pub mod panic;
333pub mod panicking;
334#[unstable(feature = "pattern_type_macro", issue = "123646")]
335pub mod pat;
336#[cfg(not(feature = "ferrocene_subset"))]
337pub mod pin;
338#[unstable(feature = "random", issue = "130703")]
339#[cfg(not(feature = "ferrocene_subset"))]
340pub mod random;
341#[cfg(not(feature = "ferrocene_subset"))]
342#[stable(feature = "new_range_inclusive_api", since = "CURRENT_RUSTC_VERSION")]
343pub mod range;
344pub mod result;
345pub mod sync;
346#[unstable(feature = "unsafe_binders", issue = "130516")]
347#[cfg(not(feature = "ferrocene_subset"))]
348pub mod unsafe_binder;
349
350pub mod fmt;
351pub mod hash;
352pub mod slice;
353pub mod str;
354pub mod time;
355
356#[cfg(not(feature = "ferrocene_subset"))]
357pub mod wtf8;
358
359pub mod unicode;
360
361/* Async */
362#[cfg(not(feature = "ferrocene_subset"))]
363pub mod future;
364#[cfg(not(feature = "ferrocene_subset"))]
365pub mod task;
366
367/* Heap memory allocator trait */
368#[allow(missing_docs)]
369pub mod alloc;
370
371// note: does not need to be public
372mod bool;
373mod escape;
374mod tuple;
375mod unit;
376
377#[stable(feature = "core_primitive", since = "1.43.0")]
378#[cfg(not(feature = "ferrocene_subset"))]
379pub mod primitive;
380
381// Pull in the `core_arch` crate directly into core. The contents of
382// `core_arch` are in a different repository: rust-lang/stdarch.
383//
384// `core_arch` depends on core, but the contents of this module are
385// set up in such a way that directly pulling it here works such that the
386// crate uses the this crate as its core.
387#[path = "../../stdarch/crates/core_arch/src/mod.rs"]
388#[allow(
389    missing_docs,
390    missing_debug_implementations,
391    dead_code,
392    unused_imports,
393    unsafe_op_in_unsafe_fn,
394    ambiguous_glob_reexports,
395    deprecated_in_future,
396    unreachable_pub
397)]
398#[allow(rustdoc::bare_urls)]
399mod core_arch;
400
401#[stable(feature = "simd_arch", since = "1.27.0")]
402pub mod arch;
403
404// Pull in the `core_simd` crate directly into core. The contents of
405// `core_simd` are in a different repository: rust-lang/portable-simd.
406//
407// `core_simd` depends on core, but the contents of this module are
408// set up in such a way that directly pulling it here works such that the
409// crate uses this crate as its core.
410#[path = "../../portable-simd/crates/core_simd/src/mod.rs"]
411#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
412#[allow(rustdoc::bare_urls)]
413#[unstable(feature = "portable_simd", issue = "86656")]
414#[cfg(not(feature = "ferrocene_subset"))]
415mod core_simd;
416
417#[unstable(feature = "portable_simd", issue = "86656")]
418#[cfg(not(feature = "ferrocene_subset"))]
419pub mod simd {
420    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
421
422    #[unstable(feature = "portable_simd", issue = "86656")]
423    pub use crate::core_simd::simd::*;
424}
425
426include!("primitive_docs.rs");