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    //! # 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`, `memcmp`, `memset` - These are core memory routines which are
    //!   often generated by LLVM. Additionally, this library can make explicit
    //!   calls to these functions. Their signatures are the same as found in C.
    //!   These functions are often provided by the system libc, but can also be
    //!   provided by the [rlibc crate](https://crates.io/crates/rlibc).
    //!
    //! * `rust_begin_panic` - This function takes four arguments, a
    //!   `fmt::Arguments`, a `&'static str`, and two `u32`'s. These four arguments
    //!   dictate the panic message, the file at which panic was invoked, and the
    //!   line and column inside the file. It is up to consumers of this core
    //!   library to define this panic function; it is only required to never
    //!   return. This requires a `lang` attribute named `panic_impl`.
    //!
    //! * `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`.

    // Since libcore defines many fundamental lang items, all tests live in a
    // separate crate, libcoretest, to avoid bizarre issues.
    //
    // Here we explicitly #[cfg]-out this whole crate when testing. If we don't do
    // this, both the generated test artifact and the linked libtest (which
    // transitively includes libcore) will both define the same set of lang items,
    // and this will cause the E0152 "duplicate lang item found" error. See
    // discussion in #50466 for details.
    //
    // This cfg won't affect doc tests.
    #![cfg(not(test))]

    #![stable(feature = "core", since = "1.6.0")]
    #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
           html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
           html_root_url = "https://doc.rust-lang.org/nightly/",
           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))))]

    #![no_core]
    #![deny(missing_docs)]
    #![deny(intra_doc_link_resolution_failure)]
    #![deny(missing_debug_implementations)]

    #![feature(allow_internal_unstable)]
    #![feature(arbitrary_self_types)]
    #![feature(asm)]
    #![feature(associated_type_defaults)]
    #![feature(cfg_target_has_atomic)]
    #![feature(concat_idents)]
    #![feature(const_fn)]
    #![cfg_attr(stage0, feature(const_int_ops))]
    #![feature(const_fn_union)]
    #![feature(custom_attribute)]
    #![feature(doc_cfg)]
    #![feature(doc_spotlight)]
    #![feature(extern_types)]
    #![feature(fundamental)]
    #![feature(intrinsics)]
    #![feature(iter_once_with)]
    #![feature(lang_items)]
    #![feature(link_llvm_intrinsics)]
    #![feature(never_type)]
    #![feature(nll)]
    #![feature(bind_by_move_pattern_guards)]
    #![feature(exhaustive_patterns)]
    #![feature(no_core)]
    #![feature(on_unimplemented)]
    #![feature(optin_builtin_traits)]
    #![feature(prelude_import)]
    #![feature(repr_simd, platform_intrinsics)]
    #![feature(rustc_attrs)]
    #![feature(rustc_const_unstable)]
    #![feature(simd_ffi)]
    #![feature(specialization)]
    #![feature(staged_api)]
    #![feature(stmt_expr_attributes)]
    #![feature(unboxed_closures)]
    #![feature(unsized_locals)]
    #![feature(untagged_unions)]
    #![feature(unwind_attributes)]
    #![feature(doc_alias)]
    #![feature(mmx_target_feature)]
    #![feature(tbm_target_feature)]
    #![feature(sse4a_target_feature)]
    #![feature(arm_target_feature)]
    #![feature(powerpc_target_feature)]
    #![feature(mips_target_feature)]
    #![feature(aarch64_target_feature)]
    #![feature(wasm_target_feature)]
    #![feature(avx512_target_feature)]
    #![cfg_attr(not(stage0), feature(cmpxchg16b_target_feature))]
    #![feature(const_slice_len)]
    #![feature(const_str_as_bytes)]
    #![feature(const_str_len)]
    #![cfg_attr(stage0, feature(const_let))]
    #![cfg_attr(stage0, feature(const_int_rotate))]
    #![feature(const_int_conversion)]
    #![feature(const_transmute)]
    #![feature(reverse_bits)]
    #![feature(non_exhaustive)]
    #![feature(structural_match)]
    #![feature(abi_unadjusted)]
    #![cfg_attr(not(stage0), feature(adx_target_feature))]

    #[prelude_import]
    #[allow(unused)]
    use prelude::v1::*;

    #[macro_use]
    mod macros;

    #[macro_use]
    mod internal_macros;

    #[path = "num/int_macros.rs"]
    #[macro_use]
    mod int_macros;

    #[path = "num/uint_macros.rs"]
    #[macro_use]
    mod uint_macros;

    #[path = "num/isize.rs"] pub mod isize;
    #[path = "num/i8.rs"]    pub mod i8;
    #[path = "num/i16.rs"]   pub mod i16;
    #[path = "num/i32.rs"]   pub mod i32;
    #[path = "num/i64.rs"]   pub mod i64;
    #[path = "num/i128.rs"]  pub mod i128;

    #[path = "num/usize.rs"] pub mod usize;
    #[path = "num/u8.rs"]    pub mod u8;
    #[path = "num/u16.rs"]   pub mod u16;
    #[path = "num/u32.rs"]   pub mod u32;
    #[path = "num/u64.rs"]   pub mod u64;
    #[path = "num/u128.rs"]  pub mod u128;

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

    #[macro_use]
    pub mod num;

    /* The libcore prelude, not as all-encompassing as the libstd prelude */

    pub mod prelude;

    /* Core modules for ownership management */

    pub mod intrinsics;
    pub mod mem;
    pub mod ptr;
    pub mod hint;

    /* Core language traits */

    pub mod marker;
    pub mod ops;
    pub mod cmp;
    pub mod clone;
    pub mod default;
    pub mod convert;
    pub mod borrow;

    /* Core types and methods on primitives */

    pub mod any;
    pub mod array;
    pub mod ascii;
    pub mod sync;
    pub mod cell;
    pub mod char;
    pub mod panic;
    pub mod panicking;
    pub mod pin;
    pub mod iter;
    pub mod option;
    pub mod raw;
    pub mod result;
    pub mod ffi;

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

    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 iter_private;
    mod tuple;
    mod unit;

    // Pull in the `coresimd` crate directly into libcore. This is where all the
    // architecture-specific (and vendor-specific) intrinsics are defined. AKA
    // things like SIMD and such. Note that the actual source for all this lies in a
    // different repository, rust-lang-nursery/stdsimd. That's why the setup here is
    // a bit wonky.
    #[allow(unused_macros)]
    macro_rules! test_v16 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! test_v32 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! test_v64 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! test_v128 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! test_v256 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! test_v512 { ($item:item) => {}; }
    #[allow(unused_macros)]
    macro_rules! vector_impl { ($([$f:ident, $($args:tt)*]),*) => { $($f!($($args)*);)* } }
    #[path = "../stdsimd/coresimd/mod.rs"]
    #[allow(missing_docs, missing_debug_implementations, dead_code, unused_imports)]
    #[unstable(feature = "stdsimd", issue = "48556")]
    mod coresimd;

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

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