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Rollup of 5 pull requests #97910

Merged
merged 11 commits into from
Jun 9, 2022
Merged

Rollup of 5 pull requests #97910

merged 11 commits into from
Jun 9, 2022

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JohnTitor
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r? @ghost
@rustbot modify labels: rollup

Create a similar rollup

evanrichter and others added 11 commits May 19, 2022 14:59
* For read and read_buf, only the front slice of a discontiguous
VecDeque is copied. The VecDeque is advanced after reading, making any
back slice available for reading with a second call to Read::read(_buf).

* For write, the VecDeque always appends the entire slice to the end,
growing its allocation when necessary.
Previously, the linker script forcefully kept all `.lib.stub` sections,
unnecessarily bloating the binary. Now, the script is LTO and
`--gc-sections` friendly.

`--nmagic` was also added to the linker, because page alignment is not
required on the PSP. This further reduces binary size.

Accompanying changes for the PSP crate are found in:
overdrivenpotato/rust-psp#118
The output of IR formatting changed slightly in upstream rev
a0bc67e
(https://reviews.llvm.org/D123096). I'm not actually sure what any of
that means, as I don't even know what hexagon is in this context, but
this change allows the test to pass on both old and new LLVMs.

r? @nikic
impl Read and Write for VecDeque<u8>

Implementing `Read` and `Write` for `VecDeque<u8>` fills in the VecDeque api surface where `Vec<u8>` and `Cursor<Vec<u8>>` already impl Read and Write. Not only for completeness, but VecDeque in particular is a very handy mock interface for a TCP echo service, if only it supported Read/Write.

Since this PR is just an impl trait, I don't think there is a way to limit it behind a feature flag, so it's "insta-stable". Please correct me if I'm wrong here, not trying to rush stability.
…lett

Stabilize `$$` in Rust 1.63.0

# Stabilization proposal

This PR proposes the stabilization of a subset of `#![feature(macro_metavar_expr)]` or more specifically, the stabilization of dollar-dollar (`$$`).

Tracking issue: rust-lang#83527
Version: 1.63 (2022-06-28 => beta, 2022-08-11 => stable).

## What is stabilized

```rust
macro_rules! foo {
    () => {
        macro_rules! bar {
            ( $$( $$any:tt )* ) => { $$( $$any )* };
        }
    };
}

fn main() {
    foo!();
}
```

## Motivation

For more examples, see the [RFC](https://github.com/markbt/rfcs/blob/macro_metavar_expr/text/0000-macro-metavar-expr.md).

Users must currently resort to a tricky and not so well-known hack to declare nested macros with repetitions.

```rust
macro_rules! foo {
    ($dollar:tt) => {
        macro_rules! bar {
            ( $dollar ( $any:tt )* ) => { $dollar ( $any )* };
        }
    };
}
fn main() {
    foo!($);
}
```

As seen above, such hack is fragile and makes work with declarative macros much more unpleasant. Dollar-dollar (`$$`), on the other hand, makes nested macros more intuitive.

## What isn't stabilized

`count`, `ignore`, `index` and `length` are not being stabilized due to the lack of consensus.

## History

* 2021-02-22, [RFC: Declarative macro metavariable expressions](rust-lang/rfcs#3086)
* 2021-03-26, [Tracking Issue for RFC 3086: macro metavariable expressions](rust-lang#83527)
* 2022-02-01, [Implement macro meta-variable expressions](rust-lang#93545)
* 2022-02-25, [[1/2] Implement macro meta-variable expressions](rust-lang#94368)
* 2022-03-11, [[2/2] Implement macro meta-variable expressions](rust-lang#94833)
* 2022-03-12, [Fix remaining meta-variable expression TODOs](rust-lang#94884)
* 2019-03-21, [[macro-metavar-expr] Fix generated tokens hygiene](rust-lang#95188)
* 2022-04-07, [Kickstart the inner usage of macro_metavar_expr](rust-lang#95761)
* 2022-04-07, [[macro_metavar_expr] Add tests to ensure the feature requirement](rust-lang#95764)

## Non-stabilized expressions

rust-lang#83527 lists several concerns about some characteristics of `count`, `index` and `length` that effectively make their stabilization unfeasible. `$$` and `ignore`, however, are not part of any discussion and thus are suitable for stabilization.

It is not in the scope of this PR to detail each concern or suggest any possible converging solution. Such thing should be restrained in this tracking issue.

## Tests

This list is a subset of https://github.com/rust-lang/rust/tree/master/src/test/ui/macros/rfc-3086-metavar-expr

* [Ensures that nested macros have correct behavior](https://github.com/rust-lang/rust/blob/master/src/test/ui/macros/rfc-3086-metavar-expr/dollar-dollar-has-correct-behavior.rs)

* [Compares produced tokens to assert expected outputs](https://github.com/rust-lang/rust/blob/master/src/test/ui/macros/rfc-3086-metavar-expr/feature-gate-macro_metavar_expr.rs)

* [Checks the declarations of the feature](https://github.com/rust-lang/rust/blob/master/src/test/ui/macros/rfc-3086-metavar-expr/required-feature.rs)

* [Verifies all possible errors that can occur due to incorrect user input](https://github.com/rust-lang/rust/blob/master/src/test/ui/macros/rfc-3086-metavar-expr/syntax-errors.rs)

## Possible future work

Once consensus is achieved, other nightly expressions can be stabilized.

Thanks ``@markbt`` for creating the RFC and thanks to ``@petrochenkov`` and ``@mark-i-m`` for reviewing the implementations.
hexagon: adapt test for upstream output changes

The output of IR formatting changed slightly in upstream rev
a0bc67e
(https://reviews.llvm.org/D123096). I'm not actually sure what any of
that means, as I don't even know what hexagon is in this context, but
this change allows the test to pass on both old and new LLVMs.

r? ``@nikic``
…woerister

Relax mipsel-sony-psp's linker script

Previously, the linker script forcefully kept all `.lib.stub` sections, unnecessarily bloating the binary. Now, the script is LTO and `--gc-sections` friendly.

`--nmagic` was also added to the linker, because page alignment is not required on the PSP. This further reduces binary size.

Accompanying changes for the `psp` crate are found in: overdrivenpotato/rust-psp#118
rewrite combine doc comment

it was from 2014 and somewhat outdated
@rustbot rustbot added 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 Jun 9, 2022
@JohnTitor
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@bors r+ rollup=never p=5

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bors commented Jun 9, 2022

📌 Commit 141b0a4 has been approved by JohnTitor

@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 Jun 9, 2022
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bors commented Jun 9, 2022

⌛ Testing commit 141b0a4 with merge a0411e2...

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bors commented Jun 9, 2022

☀️ Test successful - checks-actions
Approved by: JohnTitor
Pushing a0411e2 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Jun 9, 2022
@bors bors merged commit a0411e2 into rust-lang:master Jun 9, 2022
@rustbot rustbot added this to the 1.63.0 milestone Jun 9, 2022
@JohnTitor JohnTitor deleted the rollup-gu3k0xl branch June 9, 2022 15:40
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Finished benchmarking commit (a0411e2): comparison url.

Instruction count

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

Max RSS (memory usage)

Results
  • Primary benchmarks: mixed results
  • Secondary benchmarks: 🎉 relevant improvements found
mean1 max count2
Regressions 😿
(primary)
1.6% 1.6% 1
Regressions 😿
(secondary)
N/A N/A 0
Improvements 🎉
(primary)
-2.5% -2.5% 1
Improvements 🎉
(secondary)
-2.1% -2.1% 2
All 😿🎉 (primary) -0.5% -2.5% 2

Cycles

Results
  • Primary benchmarks: no relevant changes found
  • Secondary benchmarks: 😿 relevant regression found
mean1 max count2
Regressions 😿
(primary)
N/A N/A 0
Regressions 😿
(secondary)
2.5% 2.5% 1
Improvements 🎉
(primary)
N/A N/A 0
Improvements 🎉
(secondary)
N/A N/A 0
All 😿🎉 (primary) N/A N/A 0

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

Footnotes

  1. the arithmetic mean of the percent change 2

  2. number of relevant changes 2

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9 participants