Remove useless `'static` bounds on `Box` allocator
#79327 added `'static` bounds to the allocator parameter for various `Box` + `Pin` APIs to ensure soundness. But it was a bit overzealous, some of the bounds aren't actually needed.
Remove unnecessary unit binding
It appears that the unit binding is not necessary at this time. However, I am unsure of its importance in the past. Please let me know if it is unsafe to remove.
Fix typo in VecDeque::handle_capacity_increase() doc comment.
Strategies B and C both show a full buffer before the capacity increase, while strategy A had one empty element left. Filled the last element in.
Fix BTreeMap's Cursor::remove_{next,prev}
These would incorrectly leave `current` as `None` after a failed attempt to remove an element (due to the cursor already being at the start/end).
Additional doc links and explanation of `Wake`.
This is intended to clarify:
* That `Wake` exists and can be used instead of `RawWaker`.
* How to construct a `Waker` when you are looking at `Wake` (which was previously only documented in the example).
docs: mention round-to-even in precision formatting
_Note_: Not quite sure exactly how to format this documentation.
Mentions round-to-even usage in precision formatting. (should this also be mentioned in `f64::round`?)
From https://github.com/rust-lang/rust/issues/70336
improve `btree_cursors` functions documentation
As suggested by ``@Amanieu`` (and others) in #107540 (https://github.com/rust-lang/rust/issues/107540#issuecomment-1937760547)
Improvements:
- Document exact behavior of `{upper/lower}_bound{,_mut}` with each of the three `Bound` types using unambigous words `{greatest,greater,smallest,smaller,before,after}`.
- Added another doc-example for the `Bound::Unbounded` for each of the methods
- Changed doc-example to use From<[T; N]> rather than lots of `insert()`s which requires a mutable map which clutters the example when `mut` may not be required for the method (such as for `{upper,lower}_bound`.
- Removed `# Panics` section from `insert_{before,after}` methods since they were changed to return an error instead a while ago.
- Reworded some phrases to be more consistent with the more regular `BTreeMap` methods such as calling entries "key-value" rather than "element"s.
Create try_new function for ThinBox
The `allocator_api` feature has proven very useful in my work in the FreeBSD kernel. I've found a few places where a `ThinBox` #92791 would be useful, but it must be able to be fallibly allocated for it to be used in the kernel.
This PR proposes a change to add such a constructor for ThinBox.
ACP: https://github.com/rust-lang/libs-team/issues/213
Add some links and minor explanatory comments to `std::fmt`
I thought the documentation for the `#` flag could do with a link to the explanation of the `?xXbo` flags, because at that point they haven't been explained yet and it's a bit confusing.
I also added that the `0` flag overrides the fill character and alignment flag, here's a [Rust Playgrond](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=0d580b7b78b8a2d8c08a2fc7a936ef17) that shows what I mean.
This is intended to clarify:
* That `Wake` exists and can be used instead of `RawWaker`.
* How to construct a `Waker` when you are looking at `Wake`
(which was previously only documented in the example).
Harmonize `AsyncFn` implementations, make async closures conditionally impl `Fn*` traits
This PR implements several changes to the built-in and libcore-provided implementations of `Fn*` and `AsyncFn*` to address two problems:
1. async closures do not implement the `Fn*` family traits, leading to breakage: https://crater-reports.s3.amazonaws.com/pr-120361/index.html
2. *references* to async closures do not implement `AsyncFn*`, as a consequence of the existing blanket impls of the shape `AsyncFn for F where F: Fn, F::Output: Future`.
In order to fix (1.), we implement `Fn` traits appropriately for async closures. It turns out that async closures can:
* always implement `FnOnce`, meaning that they're drop-in compatible with `FnOnce`-bound combinators like `Option::map`.
* conditionally implement `Fn`/`FnMut` if they have no captures, which means that existing usages of async closures should *probably* work without breakage (crater checking this: https://github.com/rust-lang/rust/pull/120712#issuecomment-1930587805).
In order to fix (2.), we make all of the built-in callables implement `AsyncFn*` via built-in impls, and instead adjust the blanket impls for `AsyncFn*` provided by libcore to match the blanket impls for `Fn*`.
