make slice::{split_at,split_at_unchecked} const functions
Now that `slice::from_raw_parts` is const in stable 1.64, it makes sense to have `split_at` const as well, otherwise unsafe code is required to achieve a const equivalent.
Replace most uses of `pointer::offset` with `add` and `sub`
As PR title says, it replaces `pointer::offset` in compiler and standard library with `pointer::add` and `pointer::sub`. This generally makes code cleaner, easier to grasp and removes (or, well, hides) integer casts.
This is generally trivially correct, `.offset(-constant)` is just `.sub(constant)`, `.offset(usized as isize)` is just `.add(usized)`, etc. However in some cases we need to be careful with signs of things.
r? ````@scottmcm````
_split off from #100746_
Add `[f32]::sort_floats` and `[f64]::sort_floats`
It's inconvenient to sort a slice or Vec of floats, compared to sorting integers. To simplify numeric code, add a convenience method to `[f32]` and `[f64]` to sort them using `sort_unstable_by` with `total_cmp`.
It's inconvenient to sort a slice or Vec of floats, compared to sorting
integers. To simplify numeric code, add a convenience method to `[f32]`
and `[f64]` to sort them using `sort_unstable_by` with `total_cmp`.
Clarify slice and Vec iteration order
While already being inferable from the doc examples, it wasn't fully specified. This is the only logical way to do a slice iterator, so I think this should be uncontroversial. It also improves the `Vec::into_iter` example to better show the order and that the iterator returns owned values.
Fix some confusing wording and improve slice-search-related docs
This adds more links between `contains` and `binary_search` because I do think they have some relevant connections. If your (big) slice happens to be sorted and you know it, surely you should be using `[3; 100].binary_search(&5).is_ok()` over `[3; 100].contains(&5)`?
This also fixes the confusing "searches this sorted X" wording which just sounds really weird because it doesn't know whether it's actually sorted. It should be but it may not be. The new wording should make it clearer that you will probably want to sort it and in the same sentence it also mentions the related function `contains`.
Similarly, this mentions `binary_search` on `contains`' docs.
This also fixes some other minor stuff and inconsistencies.
Update binary_search example to instead redirect to partition_point
Inspired by discussion in the tracking issue for `Result::into_ok_or_err`: https://github.com/rust-lang/rust/issues/82223#issuecomment-1067098167
People are surprised by us not providing a `Result<T, T> -> T` conversion, and the main culprit for this confusion seems to be the `binary_search` API. We should instead redirect people to the equivalent API that implicitly does that `Result<T, T> -> T` conversion internally which should obviate the need for the `into_ok_or_err` function and give us time to work towards a more general solution that applies to all enums rather than just `Result` such as making or_patterns usable for situations like this via postfix `match`.
I choose to duplicate the example rather than simply moving it from `binary_search` to partition point because most of the confusion seems to arise when people are looking at `binary_search`. It makes sense to me to have the example presented immediately rather than requiring people to click through to even realize there is an example. If I had to put it in only one place I'd leave it in `binary_search` and remove it from `partition_point` but it seems pretty obviously relevant to `partition_point` so I figured the best option would be to duplicate it.
Bump bootstrap compiler to 1.61.0 beta
This PR bumps the bootstrap compiler to the 1.61.0 beta. The first commit changes the stage0 compiler, the second commit applies the "mechanical" changes and the third and fourth commits apply changes explained in the relevant comments.
r? `@Mark-Simulacrum`
Add debug assertions to some unsafe functions
As suggested by https://github.com/rust-lang/rust/issues/51713
~~Some similar code calls `abort()` instead of `panic!()` but aborting doesn't work in a `const fn`, and the intrinsic for doing dispatch based on whether execution is in a const is unstable.~~
This picked up some invalid uses of `get_unchecked` in the compiler, and fixes them.
I can confirm that they do in fact pick up invalid uses of `get_unchecked` in the wild, though the user experience is less-than-awesome:
```
Running unittests (target/x86_64-unknown-linux-gnu/debug/deps/rle_decode_fast-04b7918da2001b50)
running 6 tests
error: test failed, to rerun pass '--lib'
Caused by:
process didn't exit successfully: `/home/ben/rle-decode-helper/target/x86_64-unknown-linux-gnu/debug/deps/rle_decode_fast-04b7918da2001b50` (signal: 4, SIGILL: illegal instruction)
```
~~As best I can tell these changes produce a 6% regression in the runtime of `./x.py test` when `[rust] debug = true` is set.~~
Latest commit (6894d559bd) brings the additional overhead from this PR down to 0.5%, while also adding a few more assertions. I think this actually covers all the places in `core` that it is reasonable to check for safety requirements at runtime.
Thoughts?
These debug assertions are all implemented only at runtime using
`const_eval_select`, and in the error path they execute
`intrinsics::abort` instead of being a normal debug assertion to
minimize the impact of these assertions on code size, when enabled.
Of all these changes, the bounds checks for unchecked indexing are
expected to be most impactful (case in point, they found a problem in
rustc).
Constify `Index{,Mut}` for `[T]`, `str`, and `[T; N]`
Several panic functions were rewired (via `const_eval_select`) to simpler implementations that do not require formatting for compile-time usage.
r? ```@oli-obk```
This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
Track caller of slice split and swap
Improves error location for `slice.split_at*()` and `slice.swap()`.
These are generic inline functions, so the `#[track_caller]` on them is free — only changes a value of an argument already passed to panicking code.
