Merge item id stable hashing functions
Supersedes https://github.com/rust-lang/rust/pull/67999 splitting out the pure cleanup bits, i.e. merging `hash_item_id`, `hash_impl_item_id` and `hash_trait_item_id` into a common `hash_reference_to_item`.
r? @michaelwoerister
Make more arithmetic functions unstably const
This is a smaller version of #66884 (thanks @9999years) that constifies many of the arithmetic functions on integer primitives from #53718 that were blocked on #49146.
This makes the following things unstably const.
- `feature = const_int_unchecked_arith`
- `intrinsics::unchecked_add`
- `intrinsics::unchecked_sub`
- `intrinsics::unchecked_mul`
- `intrinsics::unchecked_div`
- `intrinsics::unchecked_rem`
- `feature = const_checked_int_methods`
- `checked_add`
- `checked_sub`
- `checked_mul`
- `checked_div` (Uses `intrinsics::unchecked_div` internally)
- `checked_rem` (Uses `intrinsics::unchecked_rem` internally)
- `checked_neg`
- `checked_shl`
- `checked_shr`
- `checked_abs`
- `feature = const_saturating_int_methods`
- `saturating_mul`
- `saturating_neg` (Uses `intrinsics::unchecked_sub` internally)
- `saturating_abs` (Uses `intrinsics::unchecked_sub` internally)
- `feature = const_wrapping_int_methods`
- `wrapping_div`
- `wrapping_rem`
- `feature = const_overflowing_int_methods`
- `overflowing_div`
- `overflowing_rem`
- `feature = const_euclidean_int_methods`
- `checked_div_euclid`
- `checked_rem_euclid`
- `wrapping_div_euclid`
- `wrapping_rem_euclid`
- `overflowing_div_euclid`
- `overflowing_rem_euclid`
Exponentiation and operations on the `NonZero` types are left to a later PR.
r? @oli-obk
cc @rust-lang/wg-const-eval @rust-lang/libs
Remove the `overlapping_marker_traits` feature
See #29864
This has been replaced by `#[feature(marker_trait_attr)]`
A few notes:
* Due to PR #68057 not yet being in the bootstrap compiler, it's
necessary to continue using `#![feature(overlapping_marker_traits)]`
under `#[cfg(bootstrap)]` to work around type inference issues.
* I've updated tests that used `overlapping_marker_traits` to now use
`marker_trait_attr` where applicable
The test `src/test/ui/overlap-marker-trait.rs` doesn't make any sense
now that `overlapping_marker_traits`, so I removed it.
The test `src/test/ui/traits/overlap-permitted-for-marker-traits-neg.rs`
now fails, since it's no longer possible to have multiple overlapping
negative impls of `Send`. I believe that this is the behavior we want
(assuming that `Send` is not going to become a `#[marker]` trait, so I
renamed the test to `overlap-permitted-for-marker-traits-neg`
