This method on the Iterator trait is doc(hidden), and about half of
implementations were doc(hidden). This adds the attribute to the
remaining implementations.
The previous linking seemed confusing: within "the sum() method on
iterators", "sum()" was linked to `Sum::sum`, not `Iterator::sum`, even
though the sentence is talking about the latter.
I have rewritten the sentence to be, I believe, clearer, as well as
changing the link destinations; applying the same change to the
`Product` documentation as well as `Sum`.
Link reference in `dyn` keyword documentation
The "read more" sentence formatted "object safety" as inline code
instead of providing a link to more information. This PR adds a link
to the Reference about this matter, as well as the page regarding trait
objects.
---
We could also put these links in the very first line (instead of the link to the
Book) and in the first paragraph which mentions the "object safe" requirement.
Personally, I think it's good to keep the link to the Book up-front as it's more
accessible than the Reference.
Mention the `Borrow` guarantee on the `Hash` implementations for Arrays and `Vec`
To remind people like me who forget about it and send PRs to make them different, and to (probably) get a test failure if the code is changed to no longer uphold it.
optimize Eq implementation for paths
Filesystems generally have a tree-ish structure which means paths are more likely to share a prefix than a suffix. Absolute paths are especially prone to share long prefixes.
quick benchmark consisting of a search through through a vec containing the absolute paths of all (1850) files in `compiler/`:
```
# old
test path::tests::bench_path_cmp ... bench: 227,407 ns/iter (+/- 2,162)
# new
test path::tests::bench_path_cmp ... bench: 64,976 ns/iter (+/- 1,142)
```
Updates `Clone` docs for `Copy` comparison.
Quite a few people (myself included) have come under the impression that the difference between `Copy` and `Clone` is that `Copy` is cheap and `Clone` is expensive, where the actual difference is that `Copy` constrains the type to bit-wise copying, and `Clone` allows for more expensive operations. The source of this misconception is in the `Clone` docs, where the following line is in the description:
> Differs from `Copy` in that `Copy` is implicit and extremely inexpensive, while `Clone` is always explicit and may or may not be expensive.
The `Clone` documentation page also comes up before the `Copy` page on google when searching for "the difference between `Clone` and `Copy`".
This PR updates the documentation to clarify that "extremely inexpensive" means an "inexpensive bit-wise copy" to hopefully prevent future rust users from falling into this misunderstanding.
Remove `Ipv6Addr::is_unicast_site_local`
Removes the unstable method `Ipv6Addr::is_unicast_site_local`, see also #85604 where I have tried to summarize related discussion so far.
Unicast site-local addresses (`fec0::/10`) were deprecated in [IETF RFC #3879](https://datatracker.ietf.org/doc/html/rfc3879), see also [RFC #4291 Section 2.5.7](https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.7). Any new implementation must no longer support the special behaviour of site-local addresses. This is mentioned in the docs of `is_unicast_site_local` and already implemented in `is_unicast_global`, which considers addresses in `fec0::/10` to have global scope, thus overlapping with `is_unicast_site_local`.
Given that RFC #3879 was published in 2004, long before Rust existed, and it is specified that any new implementation must no longer support the special behaviour of site-local addresses, I don't see how a user would ever have a need for `is_unicast_site_local`. It is also confusing that currently both `is_unicast_site_local` and `is_unicast_global` can be `true` for an address, but an address can actually only have a single scope. The deprecating RFC mentions that Site-Local scope was confusing to work with and that the classification of an address as either Link-Local or Global better matches the mental model of users.
There has been earlier discussion of removing `is_unicast_site_local` (https://github.com/rust-lang/rust/pull/60145#issuecomment-485970669) which decided against it, but that had the incorrect assumption that the method was already stable; it is not. (This confusion arose from the placement of the unstable attribute on the entire module, instead of on individual methods, resolved in #85672)
r? `@joshtriplett` as reviewer of all the related PRs
Integrate binary search codes of binary_search_by and partition_point
For now partition_point has own binary search code piece.
It is because binary_search_by had called the comparer more times and the author (=me) wanted to avoid it.
However, now binary_search_by uses the comparer minimum times. (#74024)
So it's time to integrate them.
The appearance of the codes are a bit different but both use completely same logic.
Stabilize {std, core}::prelude::rust_*.
This stabilizes the `{core, std}::prelude::{rust_2015, rust_2018, rust_2021}` modules.
The usage of these modules as the prelude in those editions was already stabilized. This just stabilizes the modules themselves, making it possible for a user to explicitly refer to them.
Tracking issue: https://github.com/rust-lang/rust/issues/85684
FCP on the RFC that included this finished here: https://github.com/rust-lang/rfcs/pull/3114#issuecomment-840577395
Add functions `Duration::try_from_secs_{f32, f64}`
These functions allow constructing a Duration from a floating point value that could be out of range without panicking.
Tracking issue: #83400
Explain non-dropped sender recv in docs
Original senders that are still hanging around could cause
Receiver::recv to not block since this is a potential footgun
for beginners, clarify more on this in the docs for readers to
be aware about it.
Maybe it would be better to show an example of the pattern where `drop(tx)` is used when it is being cloned multiple times? Although I have seen it in quite a few articles but I am surprised that this part is not very clear with the current words without careful reading.
> If the corresponding Sender has disconnected, or it disconnects while this call is blocking, this call will wake up and return Err to indicate that no more messages can ever be received on this channel. However, since channels are buffered, messages sent before the disconnect will still be properly received.
Some words there may seemed similar if I carefully read and relate it but if I am new, I probably does not know "drop" makes it "disconnected". So I mention the words "drop" and "alive" to make it more relatable to lifetime.
Revert #85176 addition of `clone_from` for `ManuallyDrop`
Forwarding `clone_from` to the inner value changes the observable behavior, as previously the inner value would *not* be dropped by the default implementation.
Frankly, this is a super-niche case, so #85176 is welcome to argue the behavior should be otherwise! But if we overrride it, IMO documenting the behavior would be good.
Example: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=c5d0856686fa850c1d7ee16891014efb
Implement nonzero arithmetics for NonZero types.
Hello'all, this is my first PR to this repo.
Non-zero natural numbers are stable by addition/multiplication/exponentiation, so it makes sense to make this arithmetic possible with `NonZeroU*`.
The major pitfall is that overflowing underlying `u*` types possibly lead to underlying `0` values, which break the major invariant of `NonZeroU*`. To accommodate it, only `checked_` and `saturating_` operations are implemented.
Other variants allowing wrapped results like `wrapping_` or `overflowing_` are ruled out *de facto*.
`impl Add<u*> for NonZeroU* { .. }` was considered, as it panics on overflow which enforces the invariant, but it does not so in release mode. I considered forcing `NonZeroU*::add` to panic in release mode by deferring the check to `u*::checked_add`, but this is less explicit for the user than directly using `NonZeroU*::checked_add`.
Following `@Lokathor's` advice on zulip, I have dropped the idea.
`@poliorcetics` on Discord also suggested implementing `_sub` operations, but I'd postpone this to another PR if there is a need for it. My opinion is that it could be useful in some cases, but that it makes less sense because non-null natural numbers are not stable by subtraction even in theory, while the overflowing problem is just about technical implementation.
One thing I don't like is that the type of the `other` arg differs in every implementation: `_add` methods accept any raw positive integer, `_mul` methods only accept non-zero values otherwise the invariant is also broken, and `_pow` only seems to accept `u32` for a reason I ignore but that seems consistent throughout `std`. Maybe there is a better way to harmonize this?
This is it, Iope I haven't forgotten anything and I'll be happy to read your feedback.
Original senders that are still hanging around could cause
Receiver::recv to not block since this is a potential footgun
for beginners, clarify more on this in the docs for readers to
be aware about it.
Fix minor tidbits in sender recv doc
Co-authored-by: Dylan DPC <dylan.dpc@gmail.com>
Add example for unbounded receive loops in doc
Show the drop(tx) pattern, based on tokio docs
https://tokio-rs.github.io/tokio/doc/tokio/sync/index.html
Fix example code for drop sender recv
Fix wording in sender docs
Co-authored-by: Josh Triplett <josh@joshtriplett.org>
std: Stabilize wasm simd intrinsics
This commit performs two changes to stabilize Rust support for
WebAssembly simd intrinsics:
* The stdarch submodule is updated to pull in rust-lang/stdarch#1179.
* The `wasm_target_feature` feature gate requirement for the `simd128`
feature has been removed, stabilizing the name `simd128`.
This should conclude the FCP started on #74372 and...
Closes#74372
