Add hexadecimal formatting of integers with fmt::Debug
This can be used for integers within a larger types which implements Debug (possibly through derive) but not fmt::UpperHex or fmt::LowerHex.
```rust
assert!(format!("{:02x?}", b"Foo\0") == "[46, 6f, 6f, 00]");
assert!(format!("{:02X?}", b"Foo\0") == "[46, 6F, 6F, 00]");
```
RFC: https://github.com/rust-lang/rfcs/pull/2226
The new formatting string syntax (`x?` and `X?`) is insta-stable in this PR because I don’t know how to change a built-in proc macro’s behavior based of a feature gate. I can look into adding that, but I also strongly suspect that keeping this feature unstable for a time period would not be useful as possibly no-one would use it during that time.
This PR does not add the new (public) `fmt::Formatter` proposed in the API because:
* There was some skepticism on response to this part of the RFC
* It is not possible to implement as-is without larger changes to `fmt`, because `Formatter` at the moment has no easy way to tell apart for example `Octal` from `Binary`: it only has a function pointer for the relevant `fmt()` method.
If some integer-like type outside of `std` want to implement this behavior, another RFC will likely need to propose a different public API for `Formatter`.
Stabilize inclusive range (`..=`)
Stabilize the followings:
* `inclusive_range` — The `std::ops::RangeInclusive` and `std::ops::RangeInclusiveTo` types, except its fields (tracked by #49022 separately).
* `inclusive_range_syntax` — The `a..=b` and `..=b` expression syntax
* `dotdoteq_in_patterns` — Using `a..=b` in a pattern
cc #28237
r? @rust-lang/lang
This can be used for integers within a larger types which implements Debug
(possibly through derive) but not fmt::UpperHex or fmt::LowerHex.
```rust
assert!(format!("{:02x?}", b"Foo\0") == "[46, 6f, 6f, 00]");
assert!(format!("{:02X?}", b"Foo\0") == "[46, 6F, 6F, 00]");
```
RFC: https://github.com/rust-lang/rfcs/pull/2226
Required moving all fulldeps tests depending on `rand` to different locations as
now there's multiple `rand` crates that can't be implicitly linked against.
Stabilize FusedIterator
FusedIterator is a marker trait that promises that the implementing
iterator continues to return `None` from `.next()` once it has returned
`None` once (and/or `.next_back()`, if implemented).
The effects of FusedIterator are already widely available through
`.fuse()`, but with stable `FusedIterator`, stable Rust users can
implement this trait for their iterators when appropriate.
Closes#35602
Optimize str::repeat
Improves the performance of `str::repeat` by bulk copying. Here is the benchmarks of `"abcde".repeat(n)`:
|`n`|old [ns/iter]|new [ns/iter]|diff [%]|
---|---|---|---
|1|27.205|27.421|+0.794|
|2|27.500|27.516|+0.0581|
|3|27.923|27.648|-0.985|
|4|31.206|30.145|-3.40|
|5|35.144|31.861|-9.34|
|7|43.131|34.621|-19.7|
|10|54.945|36.203|-34.1|
|100|428.31|52.895|-87.7|
FusedIterator is a marker trait that promises that the implementing
iterator continues to return `None` from `.next()` once it has returned
`None` once (and/or `.next_back()`, if implemented).
The effects of FusedIterator are already widely available through
`.fuse()`, but with stable `FusedIterator`, stable Rust users can
implement this trait for their iterators when appropriate.
[docs] Minor wording changes to drain_filter docs
The docs currently say, "If the closure returns false, it will try again, and call the closure on the next element." But this happens regardless of whether the closure returns true or false.
The docs currently say, "If the closure returns false, it will try
again, and call the closure on the next element." But this happens
regardless of whether the closure returns true or false.
boats