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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_target_has_reliable_f16_f128)]
105#![feature(const_carrying_mul_add)]
106#![feature(const_cmp)]
107#![feature(const_destruct)]
108#![feature(const_eval_select)]
109#![feature(const_select_unpredictable)]
110#![feature(core_intrinsics)]
111#![feature(coverage_attribute)]
112#![feature(disjoint_bitor)]
113#![feature(internal_impls_macro)]
114#![cfg_attr(not(feature = "ferrocene_subset"), feature(link_cfg))]
115#![cfg_attr(not(feature = "ferrocene_subset"), feature(offset_of_enum))]
116#![feature(panic_internals)]
117#![feature(pattern_type_macro)]
118#![feature(ub_checks)]
119// not-alphabetical-end
120//
121// Language features:
122// not-alphabetical-start
123#![feature(abi_unadjusted)]
124#![feature(adt_const_params)]
125#![feature(allow_internal_unsafe)]
126#![feature(allow_internal_unstable)]
127#![feature(auto_traits)]
128#![feature(cfg_sanitize)]
129#![feature(cfg_target_has_atomic)]
130#![feature(cfg_target_has_atomic_equal_alignment)]
131#![feature(cfg_ub_checks)]
132#![feature(const_precise_live_drops)]
133#![feature(const_trait_impl)]
134#![feature(decl_macro)]
135#![feature(deprecated_suggestion)]
136#![feature(derive_const)]
137#![feature(diagnostic_on_const)]
138#![feature(doc_cfg)]
139#![cfg_attr(not(feature = "ferrocene_subset"), feature(doc_notable_trait))]
140#![feature(extern_types)]
141#![feature(f128)]
142#![feature(f16)]
143#![feature(freeze_impls)]
144#![feature(fundamental)]
145#![feature(funnel_shifts)]
146#![feature(intra_doc_pointers)]
147#![feature(intrinsics)]
148#![feature(lang_items)]
149#![feature(link_llvm_intrinsics)]
150#![feature(macro_metavar_expr)]
151#![feature(macro_metavar_expr_concat)]
152#![feature(marker_trait_attr)]
153#![feature(min_specialization)]
154#![feature(multiple_supertrait_upcastable)]
155#![feature(must_not_suspend)]
156#![feature(negative_impls)]
157#![feature(never_type)]
158#![feature(no_core)]
159#![feature(optimize_attribute)]
160#![feature(pattern_types)]
161#![feature(prelude_import)]
162#![feature(repr_simd)]
163#![feature(rustc_attrs)]
164#![feature(rustdoc_internals)]
165#![feature(simd_ffi)]
166#![feature(staged_api)]
167#![feature(stmt_expr_attributes)]
168#![feature(strict_provenance_lints)]
169#![feature(target_feature_inline_always)]
170#![feature(trait_alias)]
171#![feature(transparent_unions)]
172#![feature(try_blocks)]
173#![feature(uint_carryless_mul)]
174#![feature(unboxed_closures)]
175#![feature(unsized_fn_params)]
176#![cfg_attr(not(feature = "ferrocene_subset"), feature(with_negative_coherence))]
177// not-alphabetical-end
178//
179// Target features:
180// not-alphabetical-start
181#![cfg_attr(not(feature = "ferrocene_subset"), feature(aarch64_unstable_target_feature))]
182#![feature(arm_target_feature)]
183#![cfg_attr(not(feature = "ferrocene_subset"), feature(avx10_target_feature))]
184#![cfg_attr(not(feature = "ferrocene_subset"), feature(hexagon_target_feature))]
185#![cfg_attr(not(feature = "ferrocene_subset"), feature(loongarch_target_feature))]
186#![cfg_attr(not(feature = "ferrocene_subset"), feature(mips_target_feature))]
187#![cfg_attr(not(feature = "ferrocene_subset"), feature(powerpc_target_feature))]
188#![cfg_attr(not(feature = "ferrocene_subset"), feature(nvptx_target_feature))]
189#![cfg_attr(not(feature = "ferrocene_subset"), feature(riscv_target_feature))]
190#![cfg_attr(not(feature = "ferrocene_subset"), feature(rtm_target_feature))]
191#![cfg_attr(not(feature = "ferrocene_subset"), feature(s390x_target_feature))]
192#![cfg_attr(not(feature = "ferrocene_subset"), feature(wasm_target_feature))]
193#![cfg_attr(not(feature = "ferrocene_subset"), feature(x86_amx_intrinsics))]
194// not-alphabetical-end
195//
196// Ferrocene lints/features:
197#![cfg_attr(
198    feature = "ferrocene_subset",
199    expect(rustdoc::broken_intra_doc_links),
200    expect(rustdoc::private_intra_doc_links)
201)]
202#![feature(register_tool)]
203#![register_tool(ferrocene)]
204#![doc(auto_cfg(hide(feature = "ferrocene_subset")))]
205
206// allow using `core::` in intra-doc links
207#[allow(unused_extern_crates)]
208extern crate self as core;
209
210/* The core prelude, not as all-encompassing as the std prelude */
211// The compiler expects the prelude definition to be defined before it's use statement.
212pub mod prelude;
213
214#[prelude_import]
215#[allow(unused)]
216use prelude::rust_2024::*;
217
218#[macro_use]
219mod macros;
220
221/// Ferrocene addition: Hidden module to test crate-internal functionality
222#[doc(hidden)]
223#[unstable(feature = "ferrocene_test", issue = "none")]
224#[cfg(not(feature = "ferrocene_subset"))]
225pub mod ferrocene_test;
226
227#[stable(feature = "assert_matches", since = "CURRENT_RUSTC_VERSION")]
228pub use crate::macros::{assert_matches, debug_assert_matches};
229
230#[unstable(feature = "derive_from", issue = "144889")]
231/// Unstable module containing the unstable `From` derive macro.
232pub mod from {
233    #[unstable(feature = "derive_from", issue = "144889")]
234    pub use crate::macros::builtin::From;
235}
236
237// We don't export this through #[macro_export] for now, to avoid breakage.
238#[unstable(feature = "autodiff", issue = "124509")]
239/// Unstable module containing the unstable `autodiff` macro.
240pub mod autodiff {
241    #[unstable(feature = "autodiff", issue = "124509")]
242    pub use crate::macros::builtin::{autodiff_forward, autodiff_reverse};
243}
244
245#[unstable(feature = "contracts", issue = "128044")]
246#[cfg(not(feature = "ferrocene_subset"))]
247pub mod contracts;
248
249#[stable(feature = "cfg_select", since = "CURRENT_RUSTC_VERSION")]
250pub use crate::macros::cfg_select;
251
252#[macro_use]
253mod internal_macros;
254
255#[path = "num/shells/legacy_int_modules.rs"]
256#[cfg(not(feature = "ferrocene_subset"))]
257mod legacy_int_modules;
258#[stable(feature = "rust1", since = "1.0.0")]
259#[allow(clippy::useless_attribute)] // FIXME false positive (https://github.com/rust-lang/rust-clippy/issues/15636)
260#[allow(deprecated_in_future)]
261#[cfg(not(feature = "ferrocene_subset"))]
262pub use legacy_int_modules::{i8, i16, i32, i64, isize, u8, u16, u32, u64, usize};
263#[stable(feature = "i128", since = "1.26.0")]
264#[allow(clippy::useless_attribute)] // FIXME false positive (https://github.com/rust-lang/rust-clippy/issues/15636)
265#[allow(deprecated_in_future)]
266#[cfg(not(feature = "ferrocene_subset"))]
267pub use legacy_int_modules::{i128, u128};
268
269#[path = "num/f128.rs"]
270#[cfg(not(feature = "ferrocene_subset"))]
271pub mod f128;
272#[path = "num/f16.rs"]
273pub mod f16;
274#[path = "num/f32.rs"]
275pub mod f32;
276#[path = "num/f64.rs"]
277pub mod f64;
278
279#[macro_use]
280pub mod num;
281
282/* Core modules for ownership management */
283
284pub mod hint;
285pub mod intrinsics;
286pub mod mem;
287#[unstable(feature = "profiling_marker_api", issue = "148197")]
288pub mod profiling;
289pub mod ptr;
290#[unstable(feature = "ub_checks", issue = "none")]
291pub mod ub_checks;
292
293/* Core language traits */
294
295pub mod borrow;
296pub mod clone;
297pub mod cmp;
298pub mod convert;
299pub mod default;
300#[cfg(not(feature = "ferrocene_subset"))]
301pub mod error;
302#[cfg(not(feature = "ferrocene_subset"))]
303pub mod index;
304pub mod marker;
305pub mod ops;
306
307/* Core types and methods on primitives */
308
309pub mod any;
310pub mod array;
311pub mod ascii;
312#[cfg(not(feature = "ferrocene_subset"))]
313pub mod asserting;
314#[unstable(feature = "async_iterator", issue = "79024")]
315#[cfg(not(feature = "ferrocene_subset"))]
316pub mod async_iter;
317#[unstable(feature = "bstr", issue = "134915")]
318pub mod bstr;
319pub mod cell;
320pub mod char;
321pub mod ffi;
322#[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
323#[cfg(not(feature = "ferrocene_subset"))]
324pub mod io;
325pub mod iter;
326#[cfg(not(feature = "ferrocene_subset"))]
327pub mod net;
328pub mod option;
329#[cfg(not(feature = "ferrocene_subset"))]
330pub mod os;
331pub mod panic;
332pub mod panicking;
333#[unstable(feature = "pattern_type_macro", issue = "123646")]
334pub mod pat;
335#[cfg(not(feature = "ferrocene_subset"))]
336pub mod pin;
337#[unstable(feature = "random", issue = "130703")]
338#[cfg(not(feature = "ferrocene_subset"))]
339pub mod random;
340#[cfg(not(feature = "ferrocene_subset"))]
341#[stable(feature = "new_range_inclusive_api", since = "CURRENT_RUSTC_VERSION")]
342pub mod range;
343pub mod result;
344pub mod sync;
345#[unstable(feature = "unsafe_binders", issue = "130516")]
346#[cfg(not(feature = "ferrocene_subset"))]
347pub mod unsafe_binder;
348
349pub mod fmt;
350pub mod hash;
351pub mod slice;
352pub mod str;
353pub mod time;
354
355#[cfg(not(feature = "ferrocene_subset"))]
356pub mod wtf8;
357
358pub mod unicode;
359
360/* Async */
361#[cfg(not(feature = "ferrocene_subset"))]
362pub mod future;
363#[cfg(not(feature = "ferrocene_subset"))]
364pub mod task;
365
366/* Heap memory allocator trait */
367#[allow(missing_docs)]
368pub mod alloc;
369
370// note: does not need to be public
371mod bool;
372mod escape;
373mod tuple;
374mod unit;
375
376#[stable(feature = "core_primitive", since = "1.43.0")]
377#[cfg(not(feature = "ferrocene_subset"))]
378pub mod primitive;
379
380// Pull in the `core_arch` crate directly into core. The contents of
381// `core_arch` are in a different repository: rust-lang/stdarch.
382//
383// `core_arch` depends on core, but the contents of this module are
384// set up in such a way that directly pulling it here works such that the
385// crate uses the this crate as its core.
386#[path = "../../stdarch/crates/core_arch/src/mod.rs"]
387#[allow(
388    missing_docs,
389    missing_debug_implementations,
390    dead_code,
391    unused_imports,
392    unsafe_op_in_unsafe_fn,
393    ambiguous_glob_reexports,
394    deprecated_in_future,
395    unreachable_pub
396)]
397#[allow(rustdoc::bare_urls)]
398mod core_arch;
399
400#[stable(feature = "simd_arch", since = "1.27.0")]
401pub mod arch;
402
403// Pull in the `core_simd` crate directly into core. The contents of
404// `core_simd` are in a different repository: rust-lang/portable-simd.
405//
406// `core_simd` depends on core, but the contents of this module are
407// set up in such a way that directly pulling it here works such that the
408// crate uses this crate as its core.
409#[path = "../../portable-simd/crates/core_simd/src/mod.rs"]
410#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
411#[allow(rustdoc::bare_urls)]
412#[unstable(feature = "portable_simd", issue = "86656")]
413#[cfg(not(feature = "ferrocene_subset"))]
414mod core_simd;
415
416#[unstable(feature = "portable_simd", issue = "86656")]
417#[cfg(not(feature = "ferrocene_subset"))]
418pub mod simd {
419    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
420
421    #[unstable(feature = "portable_simd", issue = "86656")]
422    pub use crate::core_simd::simd::*;
423}
424
425include!("primitive_docs.rs");