library/core/src/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`, `memcmp`, `memset` - These are core memory routines which are
  24 //!   often generated by LLVM. Additionally, this library can make explicit
  25 //!   calls to these functions. Their signatures are the same as found in C.
  26 //!   These functions are often provided by the system libc, but can also be
  27 //!   provided by the [compiler-builtins crate](https://crates.io/crates/compiler_builtins).
  28 //!
  29 //! * `rust_begin_panic` - This function takes four arguments, a
  30 //!   `fmt::Arguments`, a `&'static str`, and two `u32`'s. These four arguments
  31 //!   dictate the panic message, the file at which panic was invoked, and the
  32 //!   line and column inside the file. It is up to consumers of this core
  33 //!   library to define this panic function; it is only required to never
  34 //!   return. This requires a `lang` attribute named `panic_impl`.
  35 //!
  36 //! * `rust_eh_personality` - is used by the failure mechanisms of the
  37 //!    compiler. This is often mapped to GCC's personality function, but crates
  38 //!    which do not trigger a panic can be assured that this function is never
  39 //!    called. The `lang` attribute is called `eh_personality`.
  40
  41 // Since libcore defines many fundamental lang items, all tests live in a
  42 // separate crate, libcoretest, to avoid bizarre issues.
  43 //
  44 // Here we explicitly #[cfg]-out this whole crate when testing. If we don't do
  45 // this, both the generated test artifact and the linked libtest (which
  46 // transitively includes libcore) will both define the same set of lang items,
  47 // and this will cause the E0152 "found duplicate lang item" error. See
  48 // discussion in #50466 for details.
  49 //
  50 // This cfg won't affect doc tests.
  51 #![cfg(not(test))]
  52 // To run libcore tests without x.py without ending up with two copies of libcore, Miri needs to be
  53 // able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
  54 // rustc itself never sets the feature, so this line has no affect there.
  55 #![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
  56 #![stable(feature = "core", since = "1.6.0")]
  57 #![doc(
  58     html_playground_url = "https://play.rust-lang.org/",
  59     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
  60     test(no_crate_inject, attr(deny(warnings))),
  61     test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
  62 )]
  63 #![no_core]
  64 //
  65 // Lints:
  66 #![deny(rust_2021_incompatible_or_patterns)]
  67 #![deny(unsafe_op_in_unsafe_fn)]
  68 #![warn(deprecated_in_future)]
  69 #![warn(missing_debug_implementations)]
  70 #![warn(missing_docs)]
  71 #![allow(explicit_outlives_requirements)]
  72 #![cfg_attr(bootstrap, allow(incomplete_features))] // if_let_guard
  73 //
  74 // Library features for const fns:
  75 #![feature(const_align_of_val)]
  76 #![feature(const_alloc_layout)]
  77 #![feature(const_arguments_as_str)]
  78 #![feature(const_assert_type)]
  79 #![feature(const_caller_location)]
  80 #![feature(const_cell_into_inner)]
  81 #![feature(const_discriminant)]
  82 #![feature(const_float_bits_conv)]
  83 #![feature(const_float_classify)]
  84 #![feature(const_heap)]
  85 #![feature(const_inherent_unchecked_arith)]
  86 #![feature(const_int_unchecked_arith)]
  87 #![feature(const_intrinsic_copy)]
  88 #![feature(const_intrinsic_forget)]
  89 #![feature(const_likely)]
  90 #![feature(const_maybe_uninit_as_ptr)]
  91 #![feature(const_maybe_uninit_assume_init)]
  92 #![feature(const_option)]
  93 #![feature(const_pin)]
  94 #![feature(const_ptr_offset)]
  95 #![feature(const_ptr_offset_from)]
  96 #![feature(const_ptr_read)]
  97 #![feature(const_ptr_write)]
  98 #![feature(const_raw_ptr_comparison)]
  99 #![feature(const_size_of_val)]
 100 #![feature(const_slice_from_raw_parts)]
 101 #![feature(const_slice_ptr_len)]
 102 #![feature(const_swap)]
 103 #![feature(const_trait_impl)]
 104 #![feature(const_type_id)]
 105 #![feature(const_type_name)]
 106 #![feature(const_unreachable_unchecked)]
 107 #![feature(const_default_impls)]
 108 #![feature(duration_consts_2)]
 109 #![feature(ptr_metadata)]
 110 #![feature(slice_ptr_get)]
 111 #![feature(variant_count)]
 112 //
 113 // Language features:
 114 #![feature(abi_unadjusted)]
 115 #![feature(allow_internal_unsafe)]
 116 #![feature(allow_internal_unstable)]
 117 #![feature(asm)]
 118 #![feature(associated_type_bounds)]
 119 #![feature(auto_traits)]
 120 #![feature(cfg_target_has_atomic)]
 121 #![feature(const_fn_floating_point_arithmetic)]
 122 #![feature(const_fn_fn_ptr_basics)]
 123 #![feature(const_fn_trait_bound)]
 124 #![cfg_attr(bootstrap, feature(const_fn_transmute))]
 125 #![cfg_attr(bootstrap, feature(const_fn_union))]
 126 #![feature(const_impl_trait)]
 127 #![feature(const_mut_refs)]
 128 #![feature(const_panic)]
 129 #![feature(const_precise_live_drops)]
 130 #![feature(const_raw_ptr_deref)]
 131 #![feature(const_refs_to_cell)]
 132 #![feature(decl_macro)]
 133 #![feature(doc_cfg)]
 134 #![feature(doc_notable_trait)]
 135 #![feature(exhaustive_patterns)]
 136 #![feature(extern_types)]
 137 #![feature(fundamental)]
 138 #![feature(if_let_guard)]
 139 #![feature(intra_doc_pointers)]
 140 #![feature(intrinsics)]
 141 #![feature(lang_items)]
 142 #![feature(link_llvm_intrinsics)]
 143 #![feature(llvm_asm)]
 144 #![feature(min_specialization)]
 145 #![feature(negative_impls)]
 146 #![feature(never_type)]
 147 #![feature(no_core)]
 148 #![feature(no_coverage)] // rust-lang/rust#84605
 149 #![feature(no_niche)] // rust-lang/rust#68303
 150 #![feature(platform_intrinsics)]
 151 #![feature(prelude_import)]
 152 #![feature(repr_simd)]
 153 #![feature(rustc_allow_const_fn_unstable)]
 154 #![feature(rustc_attrs)]
 155 #![feature(simd_ffi)]
 156 #![feature(staged_api)]
 157 #![feature(stmt_expr_attributes)]
 158 #![feature(trait_alias)]
 159 #![feature(transparent_unions)]
 160 #![feature(try_blocks)]
 161 #![feature(unboxed_closures)]
 162 #![feature(unsized_fn_params)]
 163 //
 164 // Target features:
 165 #![feature(aarch64_target_feature)]
 166 #![feature(adx_target_feature)]
 167 #![feature(arm_target_feature)]
 168 #![feature(avx512_target_feature)]
 169 #![feature(cmpxchg16b_target_feature)]
 170 #![feature(f16c_target_feature)]
 171 #![feature(hexagon_target_feature)]
 172 #![feature(mips_target_feature)]
 173 #![feature(powerpc_target_feature)]
 174 #![feature(rtm_target_feature)]
 175 #![feature(sse4a_target_feature)]
 176 #![feature(tbm_target_feature)]
 177 #![feature(wasm_target_feature)]
 178
 179 // allow using `core::` in intra-doc links
 180 #[allow(unused_extern_crates)]
 181 extern crate self as core;
 182
 183 #[prelude_import]
 184 #[allow(unused)]
 185 use prelude::v1::*;
 186
 187 #[cfg(not(test))] // See #65860
 188 #[macro_use]
 189 mod macros;
 190
 191 // We don't export this through #[macro_export] for now, to avoid breakage.
 192 // See https://github.com/rust-lang/rust/issues/82913
 193 #[cfg(not(test))]
 194 #[unstable(feature = "assert_matches", issue = "82775")]
 195 /// Unstable module containing the unstable `assert_matches` macro.
 196 pub mod assert_matches {
 197     #[unstable(feature = "assert_matches", issue = "82775")]
 198     pub use crate::macros::{assert_matches, debug_assert_matches};
 199 }
 200
 201 #[macro_use]
 202 mod internal_macros;
 203
 204 #[path = "num/shells/int_macros.rs"]
 205 #[macro_use]
 206 mod int_macros;
 207
 208 #[path = "num/shells/i128.rs"]
 209 pub mod i128;
 210 #[path = "num/shells/i16.rs"]
 211 pub mod i16;
 212 #[path = "num/shells/i32.rs"]
 213 pub mod i32;
 214 #[path = "num/shells/i64.rs"]
 215 pub mod i64;
 216 #[path = "num/shells/i8.rs"]
 217 pub mod i8;
 218 #[path = "num/shells/isize.rs"]
 219 pub mod isize;
 220
 221 #[path = "num/shells/u128.rs"]
 222 pub mod u128;
 223 #[path = "num/shells/u16.rs"]
 224 pub mod u16;
 225 #[path = "num/shells/u32.rs"]
 226 pub mod u32;
 227 #[path = "num/shells/u64.rs"]
 228 pub mod u64;
 229 #[path = "num/shells/u8.rs"]
 230 pub mod u8;
 231 #[path = "num/shells/usize.rs"]
 232 pub mod usize;
 233
 234 #[path = "num/f32.rs"]
 235 pub mod f32;
 236 #[path = "num/f64.rs"]
 237 pub mod f64;
 238
 239 #[macro_use]
 240 pub mod num;
 241
 242 /* The libcore prelude, not as all-encompassing as the libstd prelude */
 243
 244 pub mod prelude;
 245
 246 /* Core modules for ownership management */
 247
 248 pub mod hint;
 249 pub mod intrinsics;
 250 pub mod mem;
 251 pub mod ptr;
 252
 253 /* Core language traits */
 254
 255 pub mod borrow;
 256 pub mod clone;
 257 pub mod cmp;
 258 pub mod convert;
 259 pub mod default;
 260 pub mod marker;
 261 pub mod ops;
 262
 263 /* Core types and methods on primitives */
 264
 265 pub mod any;
 266 pub mod array;
 267 pub mod ascii;
 268 pub mod cell;
 269 pub mod char;
 270 pub mod ffi;
 271 pub mod iter;
 272 #[unstable(feature = "once_cell", issue = "74465")]
 273 pub mod lazy;
 274 pub mod option;
 275 pub mod panic;
 276 pub mod panicking;
 277 pub mod pin;
 278 pub mod result;
 279 #[unstable(feature = "async_stream", issue = "79024")]
 280 pub mod stream;
 281 pub mod sync;
 282
 283 pub mod fmt;
 284 pub mod hash;
 285 pub mod slice;
 286 pub mod str;
 287 pub mod time;
 288
 289 pub mod unicode;
 290
 291 /* Async */
 292 pub mod future;
 293 pub mod task;
 294
 295 /* Heap memory allocator trait */
 296 #[allow(missing_docs)]
 297 pub mod alloc;
 298
 299 // note: does not need to be public
 300 mod bool;
 301 mod tuple;
 302 mod unit;
 303
 304 #[stable(feature = "core_primitive", since = "1.43.0")]
 305 pub mod primitive;
 306
 307 // Pull in the `core_arch` crate directly into libcore. The contents of
 308 // `core_arch` are in a different repository: rust-lang/stdarch.
 309 //
 310 // `core_arch` depends on libcore, but the contents of this module are
 311 // set up in such a way that directly pulling it here works such that the
 312 // crate uses the this crate as its libcore.
 313 #[path = "../../stdarch/crates/core_arch/src/mod.rs"]
 314 #[allow(
 315     missing_docs,
 316     missing_debug_implementations,
 317     dead_code,
 318     unused_imports,
 319     unsafe_op_in_unsafe_fn
 320 )]
 321 #[allow(rustdoc::bare_urls)]
 322 // FIXME: This annotation should be moved into rust-lang/stdarch after clashing_extern_declarations is
 323 // merged. It currently cannot because bootstrap fails as the lint hasn't been defined yet.
 324 #[allow(clashing_extern_declarations)]
 325 #[unstable(feature = "stdsimd", issue = "48556")]
 326 mod core_arch;
 327
 328 #[doc = include_str!("../../stdarch/crates/core_arch/src/core_arch_docs.md")]
 329 #[stable(feature = "simd_arch", since = "1.27.0")]
 330 pub mod arch {
 331     #[stable(feature = "simd_arch", since = "1.27.0")]
 332     pub use crate::core_arch::arch::*;
 333
 334     /// Inline assembly.
 335     ///
 336     /// Read the [unstable book] for the usage.
 337     ///
 338     /// [unstable book]: ../../unstable-book/library-features/asm.html
 339     #[unstable(
 340         feature = "asm",
 341         issue = "72016",
 342         reason = "inline assembly is not stable enough for use and is subject to change"
 343     )]
 344     #[rustc_builtin_macro]
 345     pub macro asm("assembly template", $(operands,)* $(options($(option),*))?) {
 346         /* compiler built-in */
 347     }
 348
 349     /// Module-level inline assembly.
 350     #[unstable(
 351         feature = "global_asm",
 352         issue = "35119",
 353         reason = "`global_asm!` is not stable enough for use and is subject to change"
 354     )]
 355     #[rustc_builtin_macro]
 356     pub macro global_asm("assembly template", $(operands,)* $(options($(option),*))?) {
 357         /* compiler built-in */
 358     }
 359 }