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Rollup of 7 pull requests #102632

Merged
merged 23 commits into from
Oct 3, 2022
Merged

Rollup of 7 pull requests #102632

merged 23 commits into from
Oct 3, 2022

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matthiaskrgr
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Successful merges:

Failed merges:

r? @ghost
@rustbot modify labels: rollup

Create a similar rollup

kpreid and others added 23 commits June 17, 2022 20:03
The wording is copied from `std::sync::atomic::AtomicPtr`, with
additional advice on how to `#[cfg]` for it.
In particular, be clear that it is sound to specify memory not
originating from a previous `Vec` allocation. That is already suggested
in other parts of the documentation about zero-alloc conversions to Box<[T]>.

Incorporate a constraint from `slice::from_raw_parts` that was missing
but needs to be fulfilled, since a `Vec` can be converted into a slice.
- Explicitly mention that `AsRef` and `AsMut` do not auto-dereference
  generally for all dereferencable types (but only if inner type is a
  shared and/or mutable reference)
- Give advice to not use `AsRef` or `AsMut` for the sole purpose of
  dereferencing
- Suggest providing a transitive `AsRef` or `AsMut` implementation for
  types which implement `Deref`
- Add new section "Reflexivity" in documentation comments for `AsRef`
  and `AsMut`
- Provide better example for `AsMut`
- Added heading "Relation to `Borrow`" in `AsRef`'s docs to improve
  structure

Issue rust-lang#45742 and a corresponding FIXME in the libcore suggest that
`AsRef` and `AsMut` should provide a blanket implementation over
`Deref`. As that is difficult to realize at the moment, this commit
updates the documentation to better describe the status-quo and to give
advice on how to use `AsRef` and `AsMut`.
Fixed examples in sections "Generic Implementations" of `AsRef`'s and
`AsMut`'s doc comments, which failed tests.
Better conform to Rust API Documentation Conventions
Changed wording in sections on "Reflexivity":
replaced "that is there is" with "i.e. there would be" and removed comma
before "with"

Reason: "there is" somewhat contradicted the "would be" hypothetical.
A slightly redundant wording has now been chosen for better clarity.
The comma seemed to be superfluous.
Document the conditional existence of `alloc::sync` and `alloc::task`.

`alloc` declares

```rust
#[cfg(target_has_atomic = "ptr")]
pub mod sync;
```

but there is no public documentation of this condition. This PR fixes that, so that users of `alloc` can understand how to make their code compile everywhere `alloc` does, if they are writing a library with impls for `Arc`.

The wording is copied from `std::sync::atomic::AtomicPtr`, with additional advice on how to `#[cfg]` for it.

I feel quite uncertain about whether the paragraph I added to `Arc`'s documentation should actually be there, as it is a distraction for anyone using `std`. On the other hand, maybe more reminders that no_std exists would benefit the ecosystem.

Note: `target_has_atomic` is [stabilized](rust-lang#32976) but [not yet documented in the reference](rust-lang/reference#1171).
docs: be less harsh in wording for Vec::from_raw_parts

In particular, be clear that it is sound to specify memory not
originating from a previous `Vec` allocation. That is already suggested
in other parts of the documentation about zero-alloc conversions to Box<[T]>.

Incorporate a constraint from `slice::from_raw_parts` that was missing
but needs to be fulfilled, since a `Vec` can be converted into a slice.

Fixes rust-lang#98780.
…riplett

docs: Improve AsRef / AsMut docs on blanket impls

There are several issues with the current state of `AsRef` and `AsMut` as [discussed here on IRLO](https://internals.rust-lang.org/t/semantics-of-asref/17016). See also rust-lang#39397, rust-lang#45742, rust-lang#73390, rust-lang#98905, and the FIXMEs [here](https://github.com/rust-lang/rust/blob/1.62.0/library/core/src/convert/mod.rs#L509-L515) and [here](https://github.com/rust-lang/rust/blob/1.62.0/library/core/src/convert/mod.rs#L530-L536). These issues are difficult to fix. This PR aims to update the documentation to better reflect the status-quo and to give advice on how `AsRef` and `AsMut` should be used.

In particular:

- Explicitly mention that `AsRef` and `AsMut` do not auto-dereference generally for all dereferencable types (but only if inner type is a shared and/or mutable reference)
- Give advice to not use `AsRef` or `AsMut` for the sole purpose of dereferencing
- Suggest providing a transitive `AsRef` or `AsMut` implementation for types which implement `Deref`
- Add new section "Reflexivity" in documentation comments for `AsRef` and `AsMut`
- Provide better example for `AsMut`
- Added heading "Relation to `Borrow`" in `AsRef`'s docs to improve structure
Tweak `FpCategory` example order.

Follow same order for variable declarations and assertions.
…default-annotated-derive, r=joshtriplett

Fix `#[derive(Default)]` on a generic `#[default]` enum adding unnecessary `Default` bounds

That is, given something like:

```rs
// #[default] on a generic enum does not add `Default` bounds to the type params.
#[derive(Default)]
enum MyOption<T> {
    #[default]
    None,
    Some(T),
}
```

then `MyOption<T> : Default`_as currently implemented_ only holds when `T : Default`, as reported by ```@5225225``` [over Zulip](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/.23.5Bderive.28Default.29.5D.20for.20enums.20with.20fields).

This is contrary to [what the accepted RFC proposes](https://rust-lang.github.io/rfcs/3107-derive-default-enum.html#generated-bounds) (_i.e._, that `T` be allowed not to be itself `Default`), and indeed seems to be a rather unnecessary limitation.
…git, r=joshtriplett

introduce `{char, u8}::is_ascii_octdigit`

This feature adds two new APIs: `char::is_ascii_octdigit` and `u8::is_ascii_octdigit`, under the feature gate `is_ascii_octdigit`. These methods are shorthands for `char::is_digit(self, 8)` and `u8::is_digit(self, 8)`:

```rust
// core::char

impl char {
    pub fn is_ascii_octdigit(self) -> bool;
}

// core::num

impl u8 {
    pub fn is_ascii_octdigit(self) -> bool;
}
```

---

Couple of things I need help understanding:

- `const`ness: have I used the right attribute in this case?
- is there a way to run the tests for `core::char` alone, instead of `./x.py test library/core`?
…compiler-errors

Add diagnostic struct for const eval error in `rustc_middle`

Part of rust-lang#100717.

r? `@ghost`
@rustbot rustbot added A-translation Area: Translation infrastructure, and migrating existing diagnostics to SessionDiagnostic T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. rollup A PR which is a rollup labels Oct 3, 2022
@matthiaskrgr
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@bors r+ rollup=never p=7

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bors commented Oct 3, 2022

📌 Commit 1b9014f has been approved by matthiaskrgr

It is now in the queue for this repository.

@bors bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Oct 3, 2022
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bors commented Oct 3, 2022

⌛ Testing commit 1b9014f with merge f83e026...

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bors commented Oct 3, 2022

☀️ Test successful - checks-actions
Approved by: matthiaskrgr
Pushing f83e026 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 3, 2022
@bors bors merged commit f83e026 into rust-lang:master Oct 3, 2022
@rustbot rustbot added this to the 1.66.0 milestone Oct 3, 2022
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📌 Perf builds for each rolled up PR:

PR# Perf Build Sha
#102486 f0283433fab88a55339d2190b1552347dea17e0e
#101308 9074e544ed385dfcf6073f2391e869c01e07ac0c
#101040 d0cb8bd2d5aff629c4848d3b211179783a83c67a
#100470 763fd20b00964ec65c0aebe6a4c9bb3df752931d
#99460 fb5bf70ae8ddf173496a7f8d67efb12403489051
#99216 50a171ed361ee8a8c72a4e35f376e1ba83aeac77
#98218 bd1b8c54b4d341baa67dbdb99887156f4ad6edb6

previous master: 0922559768

In the case of a perf regression, run the following command for each PR you suspect might be the cause: @rust-timer build $SHA

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Finished benchmarking commit (f83e026): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean1 range count2
Regressions ❌
(primary)
2.2% [2.2%, 2.2%] 1
Regressions ❌
(secondary)
3.6% [2.4%, 4.9%] 2
Improvements ✅
(primary)
- - 0
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) 2.2% [2.2%, 2.2%] 1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean1 range count2
Regressions ❌
(primary)
- - 0
Regressions ❌
(secondary)
- - 0
Improvements ✅
(primary)
-3.3% [-4.0%, -1.8%] 7
Improvements ✅
(secondary)
- - 0
All ❌✅ (primary) -3.3% [-4.0%, -1.8%] 7

Footnotes

  1. the arithmetic mean of the percent change 2

  2. number of relevant changes 2

@davidtwco davidtwco removed the A-translation Area: Translation infrastructure, and migrating existing diagnostics to SessionDiagnostic label Oct 4, 2022
@matthiaskrgr matthiaskrgr deleted the rollup-h8s3zmo branch October 9, 2022 00:31
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