Jacob Pratt 5a0c9386a2
Rollup merge of #145381 - Gnurou:int_lowest_highest_one, r=jhpratt
Implement feature `int_lowest_highest_one` for integer and NonZero types

Tracking issue: rust-lang/rust#145203

Implement the accepted ACP rust-lang/rust#145203 for methods that find the index of the least significant (lowest) and most significant (highest) set bit in an integer for signed, unsigned, and NonZero types.

Also add unit tests for all these types.
2025-08-20 00:45:56 -04:00

210 lines
5.4 KiB
Rust

// tidy-alphabetical-start
#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
#![cfg_attr(test, feature(cfg_select))]
#![feature(alloc_layout_extra)]
#![feature(array_ptr_get)]
#![feature(array_try_from_fn)]
#![feature(array_windows)]
#![feature(ascii_char)]
#![feature(ascii_char_variants)]
#![feature(async_iter_from_iter)]
#![feature(async_iterator)]
#![feature(bigint_helper_methods)]
#![feature(bool_to_result)]
#![feature(bstr)]
#![feature(cfg_target_has_reliable_f16_f128)]
#![feature(char_max_len)]
#![feature(clone_to_uninit)]
#![feature(const_deref)]
#![feature(const_destruct)]
#![feature(const_eval_select)]
#![feature(const_from)]
#![feature(const_ops)]
#![feature(const_option_ops)]
#![feature(const_ref_cell)]
#![feature(const_result_trait_fn)]
#![feature(const_trait_impl)]
#![feature(control_flow_ok)]
#![feature(core_float_math)]
#![feature(core_intrinsics)]
#![feature(core_intrinsics_fallbacks)]
#![feature(core_io_borrowed_buf)]
#![feature(core_private_bignum)]
#![feature(core_private_diy_float)]
#![feature(cstr_display)]
#![feature(dec2flt)]
#![feature(drop_guard)]
#![feature(duration_constants)]
#![feature(duration_constructors)]
#![feature(error_generic_member_access)]
#![feature(exact_div)]
#![feature(exact_size_is_empty)]
#![feature(extend_one)]
#![feature(extern_types)]
#![feature(f16)]
#![feature(f128)]
#![feature(float_algebraic)]
#![feature(float_gamma)]
#![feature(float_minimum_maximum)]
#![feature(flt2dec)]
#![feature(fmt_internals)]
#![feature(formatting_options)]
#![feature(freeze)]
#![feature(future_join)]
#![feature(generic_assert_internals)]
#![feature(hasher_prefixfree_extras)]
#![feature(hashmap_internals)]
#![feature(int_lowest_highest_one)]
#![feature(int_roundings)]
#![feature(ip)]
#![feature(is_ascii_octdigit)]
#![feature(isolate_most_least_significant_one)]
#![feature(iter_advance_by)]
#![feature(iter_array_chunks)]
#![feature(iter_collect_into)]
#![feature(iter_intersperse)]
#![feature(iter_is_partitioned)]
#![feature(iter_map_windows)]
#![feature(iter_next_chunk)]
#![feature(iter_order_by)]
#![feature(iter_partition_in_place)]
#![feature(iterator_try_collect)]
#![feature(iterator_try_reduce)]
#![feature(layout_for_ptr)]
#![feature(lazy_get)]
#![feature(maybe_uninit_fill)]
#![feature(maybe_uninit_uninit_array_transpose)]
#![feature(maybe_uninit_write_slice)]
#![feature(min_specialization)]
#![feature(never_type)]
#![feature(next_index)]
#![feature(non_exhaustive_omitted_patterns_lint)]
#![feature(numfmt)]
#![feature(pattern)]
#![feature(pointer_is_aligned_to)]
#![feature(portable_simd)]
#![feature(ptr_metadata)]
#![feature(result_option_map_or_default)]
#![feature(slice_from_ptr_range)]
#![feature(slice_internals)]
#![feature(slice_partition_dedup)]
#![feature(slice_split_once)]
#![feature(split_array)]
#![feature(split_as_slice)]
#![feature(std_internals)]
#![feature(step_trait)]
#![feature(str_internals)]
#![feature(strict_provenance_atomic_ptr)]
#![feature(strict_provenance_lints)]
#![feature(test)]
#![feature(trusted_len)]
#![feature(trusted_random_access)]
#![feature(try_blocks)]
#![feature(try_find)]
#![feature(try_trait_v2)]
#![feature(uint_bit_width)]
#![feature(unsize)]
#![feature(unwrap_infallible)]
// tidy-alphabetical-end
#![allow(internal_features)]
#![deny(fuzzy_provenance_casts)]
#![deny(unsafe_op_in_unsafe_fn)]
/// Version of `assert_matches` that ignores fancy runtime printing in const context and uses structural equality.
macro_rules! assert_eq_const_safe {
($t:ty: $left:expr, $right:expr) => {
assert_eq_const_safe!($t: $left, $right, concat!(stringify!($left), " == ", stringify!($right)));
};
($t:ty: $left:expr, $right:expr$(, $($arg:tt)+)?) => {
{
fn runtime() {
assert_eq!($left, $right, $($($arg)*),*);
}
const fn compiletime() {
const PAT: $t = $right;
assert!(matches!($left, PAT), $($($arg)*),*);
}
core::intrinsics::const_eval_select((), compiletime, runtime)
}
};
}
/// Creates a test for runtime and a test for constant-time.
macro_rules! test_runtime_and_compiletime {
($(
$(#[$attr:meta])*
fn $test:ident() $block:block
)*) => {
$(
$(#[$attr])*
#[test]
fn $test() $block
$(#[$attr])*
const _: () = $block;
)*
}
}
mod alloc;
mod any;
mod array;
mod ascii;
mod ascii_char;
mod asserting;
mod async_iter;
mod atomic;
mod bool;
mod bstr;
mod cell;
mod char;
mod clone;
mod cmp;
mod const_ptr;
mod convert;
mod ffi;
mod floats;
mod fmt;
mod future;
mod hash;
mod hint;
mod intrinsics;
mod io;
mod iter;
mod lazy;
mod macros;
mod manually_drop;
mod mem;
mod net;
mod nonzero;
mod num;
mod ops;
mod option;
mod panic;
mod pattern;
mod pin;
mod pin_macro;
mod ptr;
mod result;
mod simd;
mod slice;
mod str;
mod str_lossy;
mod task;
mod time;
mod tuple;
mod unicode;
mod waker;
/// Copied from `std::test_helpers::test_rng`, see that function for rationale.
#[track_caller]
#[allow(dead_code)] // Not used in all configurations.
pub(crate) fn test_rng() -> rand_xorshift::XorShiftRng {
use core::hash::{BuildHasher, Hash, Hasher};
let mut hasher = std::hash::RandomState::new().build_hasher();
core::panic::Location::caller().hash(&mut hasher);
let hc64 = hasher.finish();
let seed_vec = hc64.to_le_bytes().into_iter().chain(0u8..8).collect::<Vec<u8>>();
let seed: [u8; 16] = seed_vec.as_slice().try_into().unwrap();
rand::SeedableRng::from_seed(seed)
}