Improve `select_nth_unstable` documentation clarity
* Instead uses `before` and `after` variable names in the example
where `greater` and `lesser` are flipped.
* Uses `<=` and `>=` instead of "less than or equal to" and "greater
than or equal to" to make the docs more concise.
* General attempt to remove unnecessary words and be more precise. For
example it seems slightly wrong to say "its final sorted position",
since this implies there is only one sorted position for this element.
* Instead uses `before` and `after` variable names in the example
where `greater` and `lesser` are flipped.
* Uses `<=` and `>=` instead of "less than or equal to" and "greater
than or equal to" to make the docs more concise.
* General attempt to remove unnecessary words and be more precise. For
example it seems slightly wrong to say "its final sorted position",
since this implies there is only one sorted position for this element.
Rename `elem_offset` to `element_offset`
Tracking issue: #126769
Renames `slice::elem_offset` to `slice::element_offset` and improves the documentation of it and its related methods.
The current documentation can be misinterpreted (as explained [here](https://github.com/rust-lang/rust/issues/126769#issuecomment-2453363897)).
Mark `slice::copy_from_slice` unstably const
Tracking issue #131415
I used `const_eval_select` for runtime and const panic functions because const formatting isn't available yet.
Bump boostrap compiler to new beta
Currently failing due to something about the const stability checks and `panic!`. I'm not sure why though since I wasn't able to see any PRs merged in the past few days that would result in a `cfg(bootstrap)` that shouldn't be removed. cc `@RalfJung` #131349
Use consistent wording in docs, use is zero instead of is 0
In documentation, wording of _"`rhs` is zero"_ and _"`rhs` is 0"_ is intermixed. This is especially visible [here](https://doc.rust-lang.org/std/primitive.usize.html#method.div_ceil).
This changes all occurrences to _"`rhs` is zero"_ for better readability.
That is, differentiate between out-of-bounds and overlapping indices, and remove the generic parameter `N`.
I also exported `GetManyMutError` from `alloc` (and `std`), which was apparently forgotten.
Changing the error to carry additional details means LLVM no longer generates separate short-circuiting branches for the checks, instead it generates one branch at the end. I therefore changed the code to use early returns to make LLVM generate jumps. Benchmark results between the approaches are somewhat mixed, but I chose this approach because it is significantly faster with ranges and also faster with `unwrap()`.
Add `as_array` and `as_mut_array` conversion methods to slices.
Tracking issue: #133508
This PR unstably implements the `as_array` and `as_mut_array` converters to `[T]`, `*const [T]`, and `*mut [T]`.
Support ranges in `<[T]>::get_many_mut()`
As per T-libs-api decision in #104642.
I implemented that with a separate trait and not within `SliceIndex`, because doing that via `SliceIndex` requires adding support for range types that are (almost) always overlapping e.g. `RangeFrom`, and also adding fake support code for `impl SliceIndex<str>`.
An inconvenience that I ran into was that slice indexing takes the index by value, but I only have it by reference. I could change slice indexing to take by ref, but this is pretty much the hottest code ever so I'm afraid to touch it. Instead I added a requirement for `Clone` (which all index types implement anyway) and cloned. This is an internal requirement the user won't see and the clone should always be optimized away.
I also implemented `Clone`, `PartialEq` and `Eq` for the error type, since I noticed it does not do that when writing the tests and other errors in std seem to implement them. I didn't implement `Copy` because maybe we will want to put something non-`Copy` there.
I implemented that with a separate trait and not within `SliceIndex`, because doing that via `SliceIndex` requires adding support for range types that are (almost) always overlapping e.g. `RangeFrom`, and also adding fake support code for `impl SliceIndex<str>`.
An inconvenience that I ran into was that slice indexing takes the index by value, but I only have it by reference. I could change slice indexing to take by ref, but this is pretty much the hottest code ever so I'm afraid to touch it. Instead I added a requirement for `Clone` (which all index types implement anyway) and cloned. This is an internal requirement the user won't see and the clone should always be optimized away.
I also implemented `Clone`, `PartialEq` and `Eq` for the error type, since I noticed it does not do that when writing the tests and other errors in std seem to implement them. I didn't implement `Copy` because maybe we will want to put something non-`Copy` there.
Use attributes for `dangling_pointers_from_temporaries` lint
Checking for dangling pointers by function name isn't ideal, and leaves out certain pointer-returning methods that don't follow the `as_ptr` naming convention. Using an attribute for this lint cleans things up and allows more thorough coverage of other methods, such as `UnsafeCell::get()`.
