This commit adds the following functions all of which have a signature
`pointer, usize -> pointer`:
- `<*mut T>::mask`
- `<*const T>::mask`
- `intrinsics::ptr_mask`
These functions are equivalent to `.map_addr(|a| a & mask)` but they
utilize `llvm.ptrmask` llvm intrinsic.
*masks your pointers*
Windows: Load synch functions together
Attempt to load all the required sync functions and fail if any one of them fails.
This fixes a FIXME by going back to optional loading of `WakeByAddressSingle`.
Also reintroduces a macro for optional loading of functions but keeps it separate from the fallback macro rather than having that do two different jobs.
r? `@thomcc`
Fix trailing space showing up in example
The current text is rendered as: U+005B ..= U+0060 ``[ \ ] ^ _ ` ``, or (**note the final space!**)
This patch changes that to render as: U+005B ..= U+0060 `` [ \ ] ^ _ ` ``, or (**note no final space!**)
The reason for that, is that CommonMark has a solution for starting or ending inline code with a backtick/grave accent: padding both sides with a space, makes that padding disappear.
Expose `Utf8Lossy` as `Utf8Chunks`
This PR changes the feature for `Utf8Lossy` from `str_internals` to `utf8_lossy` and improves the API. This is done to eventually expose the API as stable.
Proposal: rust-lang/libs-team#54
Tracking Issue: #99543
Avoid zeroing a 1kb stack buffer on every call to `std::sys::windows::fill_utf16_buf`
I've also tried to be slightly more careful about integer overflows, although in practice this is likely still not handled ideally.
r? `@ChrisDenton`
Refactor iteration logic in the `Flatten` and `FlatMap` iterators
The `Flatten` and `FlatMap` iterators both delegate to `FlattenCompat`:
```rust
struct FlattenCompat<I, U> {
iter: Fuse<I>,
frontiter: Option<U>,
backiter: Option<U>,
}
```
Every individual iterator method that `FlattenCompat` implements needs to carefully manage this state, checking whether the `frontiter` and `backiter` are present, and storing the current iterator appropriately if iteration is aborted. This has led to methods such as `next`, `advance_by`, and `try_fold` all having similar code for managing the iterator's state.
I have extracted this common logic of iterating the inner iterators with the option to exit early into a `iter_try_fold` method:
```rust
impl<I, U> FlattenCompat<I, U>
where
I: Iterator<Item: IntoIterator<IntoIter = U>>,
{
fn iter_try_fold<Acc, Fold, R>(&mut self, acc: Acc, fold: Fold) -> R
where
Fold: FnMut(Acc, &mut U) -> R,
R: Try<Output = Acc>,
{ ... }
}
```
It passes each of the inner iterators to the given function as long as it keep succeeding. It takes care of managing `FlattenCompat`'s state, so that the actual `Iterator` methods don't need to. The resulting code that makes use of this abstraction is much more straightforward:
```rust
fn next(&mut self) -> Option<U::Item> {
#[inline]
fn next<U: Iterator>((): (), iter: &mut U) -> ControlFlow<U::Item> {
match iter.next() {
None => ControlFlow::CONTINUE,
Some(x) => ControlFlow::Break(x),
}
}
self.iter_try_fold((), next).break_value()
}
```
Note that despite being implemented in terms of `iter_try_fold`, `next` is still able to benefit from `U`'s `next` method. It therefore does not take the performance hit that implementing `next` directly in terms of `Self::try_fold` causes (in some benchmarks).
This PR also adds `iter_try_rfold` which captures the shared logic of `try_rfold` and `advance_back_by`, as well as `iter_fold` and `iter_rfold` for folding without early exits (used by `fold`, `rfold`, `count`, and `last`).
Benchmark results:
```
before after
bench_flat_map_sum 423,255 ns/iter 414,338 ns/iter
bench_flat_map_ref_sum 1,942,139 ns/iter 2,216,643 ns/iter
bench_flat_map_chain_sum 1,616,840 ns/iter 1,246,445 ns/iter
bench_flat_map_chain_ref_sum 4,348,110 ns/iter 3,574,775 ns/iter
bench_flat_map_chain_option_sum 780,037 ns/iter 780,679 ns/iter
bench_flat_map_chain_option_ref_sum 2,056,458 ns/iter 834,932 ns/iter
```
I added the last two benchmarks specifically to demonstrate an extreme case where `FlatMap::next` can benefit from custom internal iteration of the outer iterator, so take it with a grain of salt. We should probably do a perf run to see if the changes to `next` are worth it in practice.
Don't derive `PartialEq::ne`.
Currently we skip deriving `PartialEq::ne` for C-like (fieldless) enums
and empty structs, thus reyling on the default `ne`. This behaviour is
unnecessarily conservative, because the `PartialEq` docs say this:
> Implementations must ensure that eq and ne are consistent with each other:
>
> `a != b` if and only if `!(a == b)` (ensured by the default
> implementation).
This means that the default implementation (`!(a == b)`) is always good
enough. So this commit changes things such that `ne` is never derived.
The motivation for this change is that not deriving `ne` reduces compile
times and binary sizes.
Observable behaviour may change if a user has defined a type `A` with an
inconsistent `PartialEq` and then defines a type `B` that contains an
`A` and also derives `PartialEq`. Such code is already buggy and
preserving bug-for-bug compatibility isn't necessary.
Two side-effects of the change:
- There is only one error message produced for types where `PartialEq`
cannot be derived, instead of two.
- For coverage reports, some warnings about generated `ne` methods not
being executed have disappeared.
Both side-effects seem fine, and possibly preferable.
Attempt to load all the required sync functions and fail if any one of them fails.
This reintroduces a macro for optional loading of functions but keeps it separate from the fallback macro rather than having that do two different jobs.
unwind: don't build dependency when building for Miri
This is basically re-submitting https://github.com/rust-lang/rust/pull/94813.
In that PR there was a suggestion to instead have bootstrap set a `RUST_CHECK` env var and use that rather than doing something Miri-specific. However, such an env var would mean that when switching between `./x.py check` and `./x.py build`, the build script gets re-run each time, which doesn't seem good. So I think for now checking for Miri probably causes fewer problems.
r? ````@Mark-Simulacrum````
Update the minimum external LLVM to 13
With this change, we'll have stable support for LLVM 13 through 15 (pending release).
For reference, the previous increase to LLVM 12 was #90175.
r? `@nagisa`
The current text is rendered as: U+005B ..= U+0060 ``[ \ ] ^ _ ` ``, or.
This patch changes that to render as: U+005B ..= U+0060 `` [ \ ] ^ _ ` ``, or
The reason for that, is that CommonMark has a solution for starting or ending inline code with a backtick/grave accent: padding both sides with a space, makes that padding disappear.
fix(iter::skip): Optimize `next` and `nth` implementations of `Skip`
This avoids calling nth/next or nth/nth to first skip elements and then get the next one (unless necessary due to usize overflow).
Fix HorizonOS regression in FileTimes
The changes in #98246 caused a regression for multiple Newlib-based systems. This is just a fix including HorizonOS to the list of targets which require a workaround.
``@AzureMarker`` ``@ian-h-chamberlain``
r? ``@nagisa``
Add `Iterator::array_chunks` (take N+1)
A revival of https://github.com/rust-lang/rust/pull/92393.
r? `@Mark-Simulacrum`
cc `@rossmacarthur` `@scottmcm` `@the8472`
I've tried to address most of the review comments on the previous attempt. The only thing I didn't address is `try_fold` implementation, I've left the "custom" one for now, not sure what exactly should it use.
promote debug_assert to assert when possible and useful
This PR fixed a very old issue https://github.com/rust-lang/rust/issues/94705 to clarify and improve the POSIX error checking, and some of the checks are skipped because can have no benefit, but I'm sure that this can open some interesting discussion.
Fixes https://github.com/rust-lang/rust/issues/94705
cc: `@tavianator`
cc: `@cuviper`
