move mem::uninitialized deprecation back by 1 release, to 1.39
As per discussion at https://github.com/rust-lang/rust/issues/53491#issuecomment-509271182. Three releases also agrees with the precedent from `trim_left/right`. Three releases means that even nightly users (including rustc itself) get a full cycle from when the announcement is made in the stable release to when nightly starts to warn.
core: check for pointer equality when comparing Eq slices
Because `Eq` types must be reflexively equal, an equal-length slice to the same memory location must be equal.
This is related to #33892 (and #32699) answering this comment from that PR:
> Great! One more easy question: why does this optimization not apply in the non-BytewiseEquality implementation directly above?
Because slices of non-reflexively equal types (like `f64`) are not equal even if it's the same slice. But if the types are `Eq`, we can use this same-address optimization, which this PR implements. Obviously this changes behavior if types violate the reflexivity condition of `Eq`, because their impls of `PartialEq` will no longer be called per-item, but 🤷♂ .
It's not clear how often this optimization comes up in the real world outside of the same-`&str` case covered by #33892, so **I'm requesting a perf run** (on MacOS today, so can't run `rustc_perf` myself). I'm going ahead and making the PR on the basis of being surprised things didn't already work this way.
This is my first time hacking rust itself, so as a perf sanity check I ran `./x.py bench --stage 0 src/lib{std,alloc}`, but the differences were noisy.
To make the existing specialization for `BytewiseEquality` explicit, it's now a supertrait of `Eq + Copy`. `Eq` should be sufficient, but `Copy` was included for clarity.
Use variant names rather than descriptions for identifying desugarings in `#[rustc_on_unimplemented]`.
Both are highly unstable, but variant name is at least a single identifier.
The expansions were created to allow unstable things inside `#[test_case/test/bench]`, but that's not a proper way to do that.
Put the required `allow_internal_unstable`s into the macros' properties instead.
#62357: doc(ptr): add example for {read,write}_unaligned
related to #62357
> With #62323 the only example (that had UB and was thus invalid) in std::ptr::read_unaligned and std::ptr::write_unaligned is removed.
> We should add a valid example of using the aforementioned functions.
Signed-off-by: Freyskeyd <simon.paitrault@gmail.com>
Add Iterator::partition_in_place() and is_partitioned()
`partition_in_place()` swaps `&mut T` items in-place to satisfy the
predicate, so all `true` items precede all `false` items. This requires
a `DoubleEndedIterator` so we can search from front and back for items
that need swapping.
`is_partitioned()` checks whether the predicate is already satisfied.
`partition_mut()` swaps `&mut T` items in-place to satisfy the
predicate, so all `true` items precede all `false` items. This requires
a `DoubleEndedIterator` so we can search from front and back for items
that need swapping.
`is_partitioned()` checks whether the predicate is already satisfied.
TIL that debug_assert is implemented using `if cfg!(debug_assertions)`
rather than `#[cfg(debug_assertions)]`. This means one can not use API
gated with `#[cfg(debug_assertions)]` in `debug_assert` family of
macros.
Add key and value methods to DebugMap
Implementation PR for an active (not approved) RFC: https://github.com/rust-lang/rfcs/pull/2696.
Add two new methods to `std::fmt::DebugMap` for writing the key and value part of a map entry separately:
```rust
impl<'a, 'b: 'a> DebugMap<'a, 'b> {
pub fn key(&mut self, key: &dyn Debug) -> &mut Self;
pub fn value(&mut self, value: &dyn Debug) -> &mut Self;
}
```
I want to do this so that I can write a `serde::Serializer` that forwards to our format builders, so that any `T: Serialize` can also be treated like a `T: Debug`.
Only call the closure parameter of Iterator::is_sorted_by_key once per item
See https://github.com/rust-lang/rust/issues/53485#issuecomment-472314004.
This changes `Iterator::is_sorted_by_key` to only call the given closure once for each item, which allows us to pass the items to the closure by value instead of by reference.
**Important**: `is_sorted_by_key` for slices and slice iterators is now no longer implemented in terms of the custom `slice::Iter::is_sorted_by` implementation. It's a trade-off: we could forward `slice::Iter::is_sorted_by_key` to it directly for potential SIMD benefits, but that would mean that the closure is potentially called twice for (almost) every element of the slice.
- uses a never-stable core::array::LengthAtMost32 to bound the impls
- includes a custom error message to avoid mentioning LengthAtMost32 too often
- doesn't use macros for the slice implementations to avoid #62433
First question mark in doctest
We have had `?` for `Result`s in doctests for some time, but so far haven't used them in doctests. With this PR, I want to start the de-`unwrap`ping of doctests – and the discussion on where to do so.
There is one downside, which is that the code can no longer be copied into a plain `main()` method, on the other hand, there should be a workable error if one does this.
Improve documentation for built-in macros
This is the `libcore` part of https://github.com/rust-lang/rust/pull/62086.
Right now the only effect is improved documentation.
The changes in the last few commits are required to make the `libcore` change compile successfully.
Refactor unicode.py script
Hi, I noticed that the `unicode.py` script used some deprecated escapes in regular expressions. E.g. `\d`, `\w`, `\.` will be illegal in the future without "raw strings". This is now fixed. I have also cleaned up the script quite a bit.
## Escape deprecation
OK (note the `r`):
`re.compile(r"\d")`
Deprecated (from Python 3.6 onwards, see [here][link1] and [here][link2]):
`re.compile("\d")`.
[link1]: https://docs.python.org/3.6/whatsnew/3.6.html#deprecated-python-behavior
[link2]: https://bugs.python.org/issue27364
This was evident running the script using Python 3.7 like so:
```
$ python3 -Wall unicode.py
unicode.py:227: DeprecationWarning: invalid escape sequence \w
re1 = re.compile("^ *([0-9A-F]+) *; *(\w+)")
unicode.py:228: DeprecationWarning: invalid escape sequence \.
re2 = re.compile("^ *([0-9A-F]+)\.\.([0-9A-F]+) *; *(\w+)")
unicode.py:453: DeprecationWarning: invalid escape sequence \d
pattern = "for Version (\d+)\.(\d+)\.(\d+) of the Unicode"
```
The documentation states that
> A backslash-character pair that is not a valid escape sequence now generates a DeprecationWarning. Although this will eventually become a SyntaxError, that will not be for several Python releases.
## Testing
To test my changes, I had to add support for choosing the Unicode version to use. The script will default to latest release (which is 12.0.0 at the moment, repo has 11.0.0 checked in).
The script generates the exact same output for version 11.0.0 with Python 2.7 and 3.7 and no longer generates any deprecation warnings:
```
$ python3 -Wall unicode.py -v 11.0.0
Using Unicode version: 11.0.0
Regenerated tables.rs.
$ git diff tables.rs
$ python2 -Wall unicode.py -v 11.0.0
Using Unicode version: 11.0.0
Regenerated tables.rs.
$ git diff tables.rs
$ python2 --version
Python 2.7.16
$ python3 --version
Python 3.7.3
```
## Extra functionality
Furthermore, the script will check and download the latest Unicode version by default (without the `-v` argument). The `--help` is below:
```
$ ./unicode.py --help
usage: unicode.py [-h] [-v VERSION]
Regenerate Unicode tables (tables.rs).
optional arguments:
-h, --help show this help message and exit
-v VERSION, --version VERSION
Unicode version to use (if not specified, defaults to
latest available final release).
```
## Cleanups
I have cleaned up the code quite a bit, with Python best practices and code style in mind. I'm happy to provide more details and rationale for all my changes if the reviewers so desire.
One externally visible change is that the Unicode data will now be downloaded into `src/libcore/unicode/downloaded` directory suffixed by Unicode version:
```
$ pwd
.../rust/src/libcore/unicode
$ exa -T downloaded/
downloaded
├── 11.0.0
│ ├── DerivedCoreProperties.txt
│ ├── DerivedNormalizationProps.txt
│ ├── PropList.txt
│ ├── ReadMe.txt
│ ├── Scripts.txt
│ ├── SpecialCasing.txt
│ └── UnicodeData.txt
└── 12.0.0
├── DerivedCoreProperties.txt
├── DerivedNormalizationProps.txt
├── PropList.txt
├── ReadMe.txt
├── Scripts.txt
├── SpecialCasing.txt
└── UnicodeData.txt
```
