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Rollup of 8 pull requests - #87746

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bors merged 21 commits into
rust-lang:masterfrom
JohnTitor:rollup-zaapqgl
Aug 4, 2021
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Rollup of 8 pull requests#87746
bors merged 21 commits into
rust-lang:masterfrom
JohnTitor:rollup-zaapqgl

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yoshuawuytsand others added 21 commits June 23, 2021 17:49
…s_conversion)
Example:
let _x: String = String::from("hello world").into();
It's also significantly easier to read.
This way, we can show the plus and minus buttons on screens, while voice
control will read off actual words "Collapse" and "Expand" instead of reading
"open brace minus close brace" and "open brace plus close brace".
Part of rust-lang#87059
…lnay
Add `core::stream::from_iter`
_Tracking issue: https://github.com/rust-lang/rust/issues/81798_
This_ PR implements `std::stream::from_iter`, as outlined in the _"Converting an Iterator to a Stream"_ section of the [Stream RFC](https://github.com/nellshamrell/rfcs/blob/add-async-stream-rfc/text/0000-async-stream.md#converting-an-iterator-to-a-stream). This function enables converting an `Iterator` to a `Stream` by wrapping each item in the iterator with a `Poll::Ready` instance.
r? `@tmandry`
cc/ `@rust-lang/libs` `@rust-lang/wg-async-foundations`
## Example
Being able to convert from an iterator into a stream is useful when refactoring from iterative loops into a more functional adapter-based style. This is fairly common when using more complex `filter` / `map` / `find` chains. In its basic form this conversion looks like this:
**before**
```rust
let mut output = vec![];
for item in my_vec {
let out = do_io(item).await?;
output.push(out);
}
```
**after**
```rust
use std::stream;
let output = stream::from_iter(my_vec.iter())
.map(async |item| do_io(item).await)
.collect()?;
```
Having a way to convert an `Iterator` to a `Stream` is essential in enabling this flow.
## Implementation Notes
This PR makes use of `unsafe {}` to pin an item. Currently we're having conversations on the libs stream in Zulip how to bring `pin-project` in as a dependency to `core` so we can omit the `unsafe {}`.
This PR also includes a documentation block which references `Stream::next` which currently doesn't exist in the stdlib (originally included in the RFC and PR, but later omitted because of an unresolved issue). `stream::from_iter` can't stabilize before `Stream` does, and there's still a chance we may stabilize `Stream` with a `next` method. So this PR includes documentation referencing that method, which we can remove as part of stabilization if by any chance we don't have `Stream::next`.
## Alternatives Considered
### `impl IntoStream for T: IntoIterator`
An obvious question would be whether we could make it so every iterator can automatically be converted into a stream by calling `into_stream` on it. The answer is: "perhaps, but it could cause type issues". Types like `std::collections` may want to opt to create manual implementations for `IntoStream` and `IntoIter`, which wouldn't be possible if it was implemented through a catch-all trait.
Possibly an alternative such as `impl IntoStream for T: Iterator` could work, but it feels somewhat restrictive. In the end, converting an iterator to a stream is likely to be a bit of a niche case. And even then, **adding a standalone function to convert an `Iterator` into a `Stream` would not be mutually exclusive with a blanket implementation**.
### Naming
The exact name can be debated in the period before stabilization. But I've chosen `stream::from_iter` rather than `stream::iter` because we are _creating a stream from an iterator_ rather than _iterating a stream_. We also expect to add a stream counterpart to `iter::from_fn` later on (blocked on async closures), and having `stream::from_fn` and `stream::from_iter` would feel like a consistent pair. It also has prior art in `async_std::stream::from_iter`.
## Future Directions
### Stream conversions for collections
This is a building block towards implementing `stream/stream_mut/into_stream` methods for `std::collections`, `std::vec`, and more. This would allow even quicker refactorings from using loops to using iterator adapters by omitting the import altogether:
**before**
```rust
use std::stream;
let output = stream::from_iter(my_vec.iter())
.map(async |item| do_io(item).await)
.collect()?;
```
**after**
```rust
let output = my_vec
.stream()
.map(async |item| do_io(item).await)
.collect()?;
```
Remove space after negative sign in Literal to_string
Negative proc macro literal tokens used to be printed with a space between the minus sign and the magnitude. That's because `impl ToString for Literal` used to convert the Literal into a TokenStream, which splits the minus sign into a separate Punct token.
```rust
Literal::isize_unsuffixed(-10).to_string() // "- 10"
```
This PR updates the ToString impl to directly use `rustc_ast::token::Lit`'s ToString, which matches the way Rust negative numbers are idiomatically written without a space.
```rust
Literal::isize_unsuffixed(-10).to_string() // "-10"
```
…brace, r=notriddle
Rustdoc accessibility: use an icon for the [-]/[+] controls
This is a reopening of rust-lang#87207 with improvement for the way of generating the `background-image` CSS property.
I quote from the original PR:
> This way, we can show the plus and minus buttons on screens, while voice
> control will read off actual words "Collapse" and "Expand" instead of reading
> "open brace minus close brace" and "open brace plus close brace".
Part of rust-lang#87059
r? ``@notriddle``
don't use .into() to convert types to identical types (clippy::useless_conversion)
Example:
let _x: String = String::from("hello world").into();
Use .contains instead of manual reimplementation.
It's also significantly easier to read.
…=Amanieu
Remove the aarch64 `crypto` target_feature
The subfeatures `aes` or `sha2` should be used instead.
This can't yet be done for ARM targets as some LLVM intrinsics still require `crypto`.
Also update the runtime feature detection tests in `library/std` to mirror the updates in `stdarch`. This also helps rust-lang#86941
r? ``@Amanieu``
Update cargo
11 commits in d21c22870e58499d6c31f1bef3bf1255eb021666..cc17afbb0067b1f57d8882640f63b2168d5b7624
2021-07-26 20:23:21 +0000 to 2021-08-02 20:28:08 +0000
- Stabilize the rust-version field (rust-lang/cargo#9732)
- Remove nbsp characters. (rust-lang/cargo#9751)
- Update unstable documentation TOC. (rust-lang/cargo#9750)
- Some minor updates for package/publish package selection. (rust-lang/cargo#9749)
- Bump to 0.57.0, update changelog (rust-lang/cargo#9748)
- Stabilize `[env]` sections (rust-lang/cargo#9411)
- doc: Clarify [doc].browser docs, document PathAndArgs better (rust-lang/cargo#9747)
- Bump cargo-util version. (rust-lang/cargo#9745)
- Make clippy happy (rust-lang/cargo#9736)
- Fix typo in features doc (rust-lang/cargo#9737)
- doc test supports silent output (rust-lang/cargo#9730)
…Artichaut
Test dropping union fields more
Now that rust-lang#87403 is merged, a few more tests can be added for reads/writes to dropping union fields.
r? ``@LeSeulArtichaut``
@rustbotrustbot added the rollup A PR which is a rollup label Aug 3, 2021
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@bors r+ p=8 rollup=never

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bors commented Aug 3, 2021

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📌 Commit 7c5588e has been approved by JohnTitor

@borsbors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Aug 3, 2021
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bors commented Aug 3, 2021

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⌛ Testing commit 7c5588e with merge 2b8de6f...

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bors commented Aug 4, 2021

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☀️ Test successful - checks-actions
Approved by: JohnTitor
Pushing 2b8de6f to master...

@borsbors added the merged-by-bors This PR was explicitly merged by bors. label Aug 4, 2021
@borsbors mentioned this pull request Aug 4, 2021
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bors merged commit 2b8de6f into rust-lang:masterAug 4, 2021
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@JohnTitor@bors@rustbot@yoshuawuyts@matthiaskrgr@frogtd@adamgemmell@notriddle@ehuss@dtolnay@GuillaumeGomez@syvb