rust/library/core/tests/lib.rs
Jubilee 3313e760d0
Rollup merge of #132423 - RalfJung:const-eval-align-offset, r=dtolnay
remove const-support for align_offset and is_aligned

As part of the recent discussion to stabilize `ptr.is_null()` in const context, the general vibe was that it's okay for a const function to panic when the same operation would work at runtime (that's just a case of "dynamically detecting that something is not supported as a const operation"), but it is *not* okay for a const function to just return a different result.

Following that, `is_aligned` and `is_aligned_to` have their const status revoked in this PR, since they do return actively wrong results at const time. In the future we can consider having a new intrinsic or so that can check whether a pointer is "guaranteed to be aligned", but the current implementation based on `align_offset` does not have the behavior we want.

In fact `align_offset` itself behaves quite strangely in const, and that support needs a bunch of special hacks. That doesn't seem worth it. Instead, the users that can fall back to a different implementation should just use const_eval_select directly, and everything else should not be made const-callable. So this PR does exactly that, and entirely removes const support for align_offset.

Closes some tracking issues by removing the associated features:
Closes https://github.com/rust-lang/rust/issues/90962
Closes https://github.com/rust-lang/rust/issues/104203

Cc `@rust-lang/wg-const-eval` `@rust-lang/libs-api`
2024-11-03 20:08:13 -08:00

194 lines
5.0 KiB
Rust

// tidy-alphabetical-start
#![cfg_attr(bootstrap, feature(strict_provenance))]
#![cfg_attr(not(bootstrap), feature(strict_provenance_lints))]
#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
#![cfg_attr(test, feature(cfg_match))]
#![feature(alloc_layout_extra)]
#![feature(array_chunks)]
#![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(cell_update)]
#![feature(clone_to_uninit)]
#![feature(const_align_of_val_raw)]
#![feature(const_black_box)]
#![feature(const_eval_select)]
#![feature(const_heap)]
#![feature(const_nonnull_new)]
#![feature(const_option_ext)]
#![feature(const_pin_2)]
#![feature(const_three_way_compare)]
#![feature(const_trait_impl)]
#![feature(core_intrinsics)]
#![feature(core_io_borrowed_buf)]
#![feature(core_private_bignum)]
#![feature(core_private_diy_float)]
#![feature(dec2flt)]
#![feature(duration_constants)]
#![feature(duration_constructors)]
#![feature(error_generic_member_access)]
#![feature(exact_size_is_empty)]
#![feature(extern_types)]
#![feature(float_minimum_maximum)]
#![feature(flt2dec)]
#![feature(fmt_internals)]
#![feature(freeze)]
#![feature(future_join)]
#![feature(generic_assert_internals)]
#![feature(get_many_mut)]
#![feature(hasher_prefixfree_extras)]
#![feature(hashmap_internals)]
#![feature(inline_const_pat)]
#![feature(int_roundings)]
#![feature(ip)]
#![feature(ip_from)]
#![feature(is_ascii_octdigit)]
#![feature(iter_advance_by)]
#![feature(iter_array_chunks)]
#![feature(iter_chain)]
#![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(noop_waker)]
#![feature(num_midpoint)]
#![feature(numfmt)]
#![feature(pattern)]
#![feature(pointer_is_aligned_to)]
#![feature(portable_simd)]
#![feature(ptr_metadata)]
#![feature(slice_from_ptr_range)]
#![feature(slice_internals)]
#![feature(slice_partition_dedup)]
#![feature(slice_split_once)]
#![feature(slice_take)]
#![feature(split_array)]
#![feature(split_as_slice)]
#![feature(std_internals)]
#![feature(step_trait)]
#![feature(str_internals)]
#![feature(strict_provenance_atomic_ptr)]
#![feature(test)]
#![feature(trait_upcasting)]
#![feature(trusted_len)]
#![feature(trusted_random_access)]
#![feature(try_blocks)]
#![feature(try_find)]
#![feature(try_trait_v2)]
#![feature(unsigned_is_multiple_of)]
#![feature(unsize)]
#![feature(unsized_tuple_coercion)]
#![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 {
($left:expr, $right:expr$(, $($arg:tt)+)?) => {
{
fn runtime() {
assert_eq!($left, $right, $($arg)*);
}
const fn compiletime() {
assert!(matches!($left, const { $right }));
}
core::intrinsics::const_eval_select((), compiletime, runtime)
}
};
}
/// Creates a test for runtime and a test for constant-time.
macro_rules! test_runtime_and_compiletime {
($(
$(#[$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 cell;
mod char;
mod clone;
mod cmp;
mod const_ptr;
mod convert;
mod ffi;
mod fmt;
mod future;
mod hash;
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)
}