core/

lib.rs

//! # The Rust Core Library
//!
//! The Rust Core Library is the dependency-free[^free] foundation of [The
//! Rust Standard Library](../std/index.html). It is the portable glue
//! between the language and its libraries, defining the intrinsic and
//! primitive building blocks of all Rust code. It links to no
//! upstream libraries, no system libraries, and no libc.
//!
//! [^free]: Strictly speaking, there are some symbols which are needed but
//!          they aren't always necessary.
//!
//! The core library is *minimal*: it isn't even aware of heap allocation,
//! nor does it provide concurrency or I/O. These things require
//! platform integration, and this library is platform-agnostic.
//!
//! # How to use the core library
//!
//! Please note that all of these details are currently not considered stable.
//!
// FIXME: Fill me in with more detail when the interface settles
//! This library is built on the assumption of a few existing symbols:
//!
//! * `memcpy`, `memmove`, `memset`, `memcmp`, `bcmp`, `strlen` - These are core memory routines
//!   which are generated by Rust codegen backends. Additionally, this library can make explicit
//!   calls to `strlen`. Their signatures are the same as found in C, but there are extra
//!   assumptions about their semantics: For `memcpy`, `memmove`, `memset`, `memcmp`, and `bcmp`, if
//!   the `n` parameter is 0, the function is assumed to not be UB, even if the pointers are NULL or
//!   dangling. (Note that making extra assumptions about these functions is common among compilers:
//!   [clang](https://reviews.llvm.org/D86993) and [GCC](https://gcc.gnu.org/onlinedocs/gcc/Standards.html#C-Language) do the same.)
//!   These functions are often provided by the system libc, but can also be provided by the
//!   [compiler-builtins crate](https://crates.io/crates/compiler_builtins).
//!   Note that the library does not guarantee that it will always make these assumptions, so Rust
//!   user code directly calling the C functions should follow the C specification! The advice for
//!   Rust user code is to call the functions provided by this library instead (such as
//!   `ptr::copy`).
//!
//! * Panic handler - This function takes one argument, a `&panic::PanicInfo`. It is up to consumers of this core
//!   library to define this panic function; it is only required to never
//!   return. You should mark your implementation using `#[panic_handler]`.
//!
//! * `rust_eh_personality` - is used by the failure mechanisms of the
//!   compiler. This is often mapped to GCC's personality function, but crates
//!   which do not trigger a panic can be assured that this function is never
//!   called. The `lang` attribute is called `eh_personality`.

#![stable(feature = "core", since = "1.6.0")]
#![doc(
    html_playground_url = "https://play.rust-lang.org/",
    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
    test(no_crate_inject, attr(deny(warnings))),
    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut, duplicate_features)))
)]
#![doc(rust_logo)]
#![doc(auto_cfg(
    hide(no_fp_fmt_parse),
    hide(target_pointer_width, values("16", "32", "64")),
    hide(
        target_has_atomic,
        target_has_atomic_primitive_alignment,
        target_has_atomic_load_store,
        values("8", "16", "32", "64", "ptr"),
    ),
))]
#![no_core]
#![rustc_coherence_is_core]
#![rustc_preserve_ub_checks]
//
// Lints:
#![deny(rust_2021_incompatible_or_patterns)]
#![deny(unsafe_op_in_unsafe_fn)]
#![deny(implicit_provenance_casts)]
#![warn(deprecated_in_future)]
#![warn(missing_debug_implementations)]
#![warn(missing_docs)]
#![allow(explicit_outlives_requirements)]
#![allow(incomplete_features)]
#![warn(multiple_supertrait_upcastable)]
#![allow(internal_features)]
#![allow(unused_features)]
#![deny(ffi_unwind_calls)]
#![warn(unreachable_pub)]
// Do not check link redundancy on bootstrapping phase
#![allow(rustdoc::redundant_explicit_links)]
#![warn(rustdoc::unescaped_backticks)]
//
// Ferrocene addition: require transitive closure of prevalidated functions.
#![warn(ferrocene::unvalidated)]
// Ferrocene addition: We removed the tidy directives for alphabetical ordering to reduce the number
// of conflicts we have when merging main.
//
// Library features:
// not-alphabetical-start
#![feature(asm_experimental_arch)]
#![feature(bstr_internals)]
#![feature(cfg_target_has_reliable_f16_f128)]
#![feature(const_carrying_mul_add)]
#![feature(const_cmp)]
#![feature(const_destruct)]
#![feature(const_eval_select)]
#![feature(const_select_unpredictable)]
#![feature(core_intrinsics)]
#![feature(coverage_attribute)]
#![feature(disjoint_bitor)]
#![feature(io_const_error)]
#![feature(offset_of_enum)]
#![feature(panic_internals)]
#![feature(pattern_type_macro)]
#![feature(ub_checks)]
// not-alphabetical-end
//
// Language features:
#![feature(adt_const_params)]
#![feature(allow_internal_unsafe)]
#![feature(allow_internal_unstable)]
#![feature(arbitrary_self_types_pointers)]
#![feature(auto_traits)]
#![feature(cfg_sanitize)]
#![feature(cfg_target_has_atomic)]
#![feature(cfg_ub_checks)]
#![feature(const_closures)]
#![feature(const_precise_live_drops)]
#![feature(const_trait_impl)]
#![feature(decl_macro)]
#![feature(deprecated_suggestion)]
#![feature(derive_const)]
#![feature(diagnostic_on_const)]
#![feature(diagnostic_on_unmatched_args)]
#![feature(diagnostic_opaque)]
#![feature(doc_cfg)]
#![feature(doc_notable_trait)]
#![feature(extern_types)]
#![feature(f128)]
#![feature(f16)]
#![feature(field_projections)]
#![feature(final_associated_functions)]
#![feature(freeze_impls)]
#![feature(fundamental)]
#![feature(funnel_shifts)]
#![feature(impl_restriction)]
#![feature(intra_doc_pointers)]
#![feature(intrinsics)]
#![feature(lang_items)]
#![feature(link_cfg)]
#![feature(link_llvm_intrinsics)]
#![feature(macro_metavar_expr)]
#![feature(macro_metavar_expr_concat)]
#![feature(marker_trait_attr)]
#![feature(min_specialization)]
#![feature(multiple_supertrait_upcastable)]
#![feature(must_not_suspend)]
#![feature(negative_impls)]
#![feature(no_core)]
#![feature(optimize_attribute)]
#![feature(pattern_types)]
#![feature(pin_macro_internals)]
#![feature(prelude_import)]
#![feature(repr_simd)]
#![feature(rustc_attrs)]
#![feature(rustdoc_internals)]
#![feature(simd_ffi)]
#![feature(splat)]
#![feature(staged_api)]
#![feature(stmt_expr_attributes)]
#![feature(strict_provenance_lints)]
#![feature(trait_alias)]
#![feature(transparent_unions)]
#![feature(try_blocks)]
#![feature(uint_carryless_mul)]
#![feature(unboxed_closures)]
#![feature(unsized_fn_params)]
#![feature(with_negative_coherence)]
// not-alphabetical-end
//
// Target features:
// not-alphabetical-start
#![feature(aarch64_unstable_target_feature)]
#![feature(arm_target_feature)]
#![feature(avx10_target_feature)]
#![feature(clflushopt_target_feature)]
#![feature(hexagon_target_feature)]
#![feature(loongarch_target_feature)]
#![feature(mips_target_feature)]
#![feature(movrs_target_feature)]
#![feature(powerpc_target_feature)]
#![feature(nvptx_target_feature)]
#![feature(riscv_target_feature)]
#![feature(rtm_target_feature)]
#![feature(s390x_target_feature)]
#![feature(wasm_target_feature)]
#![feature(x86_amx_intrinsics)]
// not-alphabetical-end

// tidy-alphabetical-start
#![expect(clippy::partialeq_ne_impl, reason = "we need to implement ne for a lot of core types")]
// tidy-alphabetical-end

// allow using `core::` in intra-doc links
#[allow(unused_extern_crates)]
extern crate self as core;

/* The core prelude, not as all-encompassing as the std prelude */
// The compiler expects the prelude definition to be defined before it's use statement.
pub mod prelude;

#[prelude_import]
#[allow(unused)]
use prelude::rust_2024::*;

#[macro_use]
mod macros;

/// Ferrocene addition: Hidden module to test crate-internal functionality
#[doc(hidden)]
#[unstable(feature = "ferrocene_test", issue = "none")]
pub mod ferrocene_test;

#[stable(feature = "assert_matches", since = "1.96.0")]
pub use crate::macros::{assert_matches, debug_assert_matches};

#[unstable(feature = "derive_from", issue = "144889")]
/// Unstable module containing the unstable `From` derive macro.
pub mod from {
    #[unstable(feature = "derive_from", issue = "144889")]
    pub use crate::macros::builtin::From;
}

// We don't export this through #[macro_export] for now, to avoid breakage.
#[unstable(feature = "autodiff", issue = "124509")]
#[doc = include_str!("../../core/src/autodiff.md")]
pub mod autodiff {
    #[unstable(feature = "autodiff", issue = "124509")]
    pub use crate::macros::builtin::{autodiff_forward, autodiff_reverse};
}

#[unstable(feature = "gpu_offload", issue = "131513")]
#[doc = include_str!("../../core/src/offload.md")]
pub mod offload;

#[unstable(feature = "contracts", issue = "128044")]
pub mod contracts;

#[allow(clippy::useless_attribute)]
#[expect(
    ineffective_unstable_reexports,
    reason = "accepted as stable after accidental stabilization in 1.96, see #154645"
)]
#[unstable(feature = "derive_macro_global_path", issue = "154645")]
pub use crate::macros::builtin::derive;
#[stable(feature = "cfg_select", since = "1.95.0")]
pub use crate::macros::cfg_select;

#[macro_use]
mod internal_macros;

#[path = "num/shells/legacy_int_modules.rs"]
mod legacy_int_modules;
#[stable(feature = "rust1", since = "1.0.0")]
#[allow(deprecated, clippy::legacy_numeric_constants)]
pub use legacy_int_modules::{i8, i16, i32, i64, isize, u8, u16, u32, u64, usize};
#[stable(feature = "i128", since = "1.26.0")]
#[allow(deprecated, clippy::legacy_numeric_constants)]
pub use legacy_int_modules::{i128, u128};

#[path = "num/f128.rs"]
pub mod f128;
#[path = "num/f16.rs"]
pub mod f16;
#[path = "num/f32.rs"]
pub mod f32;
#[path = "num/f64.rs"]
pub mod f64;

#[macro_use]
pub mod num;

/* Core modules for ownership management */

pub mod hint;
pub mod intrinsics;
pub mod mem;
#[unstable(feature = "profiling_marker_api", issue = "148197")]
pub mod profiling;
pub mod ptr;
#[unstable(feature = "ub_checks", issue = "none")]
pub mod ub_checks;

/* Core language traits */

pub mod borrow;
pub mod clone;
pub mod cmp;
pub mod convert;
pub mod default;
pub mod error;
#[unstable(feature = "field_projections", issue = "145383")]
pub mod field;
pub mod index;
pub mod marker;
pub mod ops;

/* Core types and methods on primitives */

pub mod any;
pub mod array;
pub mod ascii;
pub mod asserting;
#[unstable(feature = "async_iterator", issue = "79024")]
pub mod async_iter;
#[unstable(feature = "bstr", issue = "134915")]
pub mod bstr;
pub mod cell;
pub mod char;
pub mod ffi;
#[unstable(feature = "core_io", issue = "154046")]
pub mod io;
pub mod iter;
pub mod net;
pub mod option;
pub mod os;
pub mod panic;
pub mod panicking;
#[unstable(feature = "pattern_type_macro", issue = "123646")]
pub mod pat;
pub mod pin;
#[unstable(feature = "abort_immediate", issue = "154601")]
pub mod process;
#[unstable(feature = "random", issue = "130703")]
pub mod random;
#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
pub mod range;
pub mod result;
pub mod sync;
#[unstable(feature = "unsafe_binders", issue = "130516")]
pub mod unsafe_binder;

pub mod fmt;
pub mod hash;
pub mod slice;
pub mod str;
pub mod time;

pub mod wtf8;

pub mod unicode;

/* Async */
pub mod future;
pub mod task;

/* Heap memory allocator trait */
#[allow(missing_docs)]
pub mod alloc;

// note: does not need to be public
mod bool;
mod escape;
mod tuple;
mod unit;
#[unstable(feature = "view_type_macro", issue = "155938")]
pub mod view;

#[stable(feature = "core_primitive", since = "1.43.0")]
pub mod primitive;

// Pull in the `core_arch` crate directly into core. The contents of
// `core_arch` are in a different repository: rust-lang/stdarch.
//
// `core_arch` depends on core, but the contents of this module are
// set up in such a way that directly pulling it here works such that the
// crate uses the this crate as its core.
#[path = "../../stdarch/crates/core_arch/src/mod.rs"]
#[allow(
    missing_docs,
    missing_debug_implementations,
    dead_code,
    unused_imports,
    unsafe_op_in_unsafe_fn,
    ambiguous_glob_reexports,
    unreachable_pub,
    // FIXME: stdach is a submodule so clippy lints should be fixed (and ideally enforced) there
    clippy::all,
)]
#[allow(rustdoc::bare_urls)]
mod core_arch;

#[stable(feature = "simd_arch", since = "1.27.0")]
pub mod arch;

// Pull in the `core_simd` crate directly into core. The contents of
// `core_simd` are in a different repository: rust-lang/portable-simd.
//
// `core_simd` depends on core, but the contents of this module are
// set up in such a way that directly pulling it here works such that the
// crate uses this crate as its core.
#[path = "../../portable-simd/crates/core_simd/src/mod.rs"]
#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
#[allow(rustdoc::bare_urls)]
#[unstable(feature = "portable_simd", issue = "86656")]
mod core_simd;

#[unstable(feature = "portable_simd", issue = "86656")]
pub mod simd {
    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]

    #[unstable(feature = "portable_simd", issue = "86656")]
    pub use crate::core_simd::simd::*;
}

// Include private modules that exist solely to provide rustdoc
// documentation for built-in attributes. Using `include!` because rustdoc
// only looks for these modules at the crate level.
include!("attribute_docs.rs");

// Include a number of private modules that exist solely to provide
// the rustdoc documentation for the existing keywords. Using `include!`
// because rustdoc only looks for these modules at the crate level.
include!("keyword_docs.rs");

// Include a number of private modules that exist solely to provide
// the rustdoc documentation for primitive types. Using `include!`
// because rustdoc only looks for these modules at the crate level.
include!("primitive_docs.rs");