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Kickstart the inner usage of macro_metavar_expr #95761

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merged 1 commit into from
Apr 8, 2022
Merged

Kickstart the inner usage of macro_metavar_expr #95761

merged 1 commit into from
Apr 8, 2022

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c410-f3r
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@c410-f3r c410-f3r commented Apr 7, 2022 •
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There can be more use-cases but I am out of ideas.

cc #83527
r? @petrochenkov

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 7, 2022
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klensy commented Apr 7, 2022

array_impl_default?

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ignore can be used in fn add_placeholders in the compiler.

@petrochenkov petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 7, 2022
@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Apr 7, 2022
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c410-f3r commented Apr 7, 2022

ignore can be used in fn add_placeholders in the compiler.

Done

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c410-f3r commented Apr 7, 2022 •
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array_impl_default?

Thanks. I will see if it is worth changing the current macro structure in a following PR

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c410-f3r commented Apr 7, 2022 •
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@rustbot label -S-waiting-on-author +S-waiting-on-review

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Error: Label review can only be set by Rust team members

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Error: Label author can only be set by Rust team members

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 7, 2022
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@bors r+

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bors commented Apr 7, 2022

📌 Commit 3191d27 has been approved by petrochenkov

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 7, 2022
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Apr 8, 2022
@Dylan-DPC
Rollup merge of rust-lang#95761 - c410-f3r:meta-var-stuff, r=petroche…
b9b64b1 
…nkov

Kickstart the inner usage of `macro_metavar_expr`

There can be more use-cases but I am out of ideas.

cc rust-lang#83527
r? `@petrochenkov`
@Dylan-DPC Dylan-DPC mentioned this pull request Apr 8, 2022
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@Dylan-DPC Dylan-DPC mentioned this pull request Apr 8, 2022
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bors added a commit to rust-lang-ci/rust that referenced this pull request Apr 8, 2022
@bors
Auto merge of rust-lang#95798 - Dylan-DPC:rollup-51hx1wl, r=Dylan-DPC
e4f5b15 
Rollup of 7 pull requests

Successful merges:

 - rust-lang#95102 (Add known-bug for rust-lang#95034)
 - rust-lang#95579 (Add `<[[T; N]]>::flatten{_mut}`)
 - rust-lang#95634 (Mailmap update)
 - rust-lang#95705 (Promote x86_64-unknown-none target to Tier 2 and distribute build artifacts)
 - rust-lang#95761 (Kickstart the inner usage of `macro_metavar_expr`)
 - rust-lang#95782 (Windows: Increase a pipe's buffer capacity to 64kb)
 - rust-lang#95791 (hide an #[allow] directive from the Arc::new_cyclic doc example)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 1f80881 into rust-lang:master Apr 8, 2022
@rustbot rustbot added this to the 1.62.0 milestone Apr 8, 2022
c410-f3r added a commit to c410-f3r/rust that referenced this pull request Apr 8, 2022
@c410-f3r
Left overs of rust-lang#95761
e946aa3
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Apr 9, 2022
@matthiaskrgr
Rollup merge of rust-lang#95805 - c410-f3r:meta-vars, r=petrochenkov
fcccbb0 
Left overs of rust-lang#95761

These are just nits. Feel free to close this PR if all modifications are not worth merging.

* `#![feature(decl_macro)]` is not needed anymore in `rustc_expand`
* `tuple_impls` does not require `$Tuple:ident`. I guess it is there to enhance readability?

r? `@petrochenkov`
@matthiaskrgr matthiaskrgr mentioned this pull request Apr 9, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Apr 9, 2022
@Dylan-DPC
Rollup merge of rust-lang#95805 - c410-f3r:meta-vars, r=petrochenkov
210c361 
Left overs of rust-lang#95761

These are just nits. Feel free to close this PR if all modifications are not worth merging.

* `#![feature(decl_macro)]` is not needed anymore in `rustc_expand`
* `tuple_impls` does not require `$Tuple:ident`. I guess it is there to enhance readability?

r? ``@petrochenkov``
@Dylan-DPC Dylan-DPC mentioned this pull request Apr 9, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Apr 9, 2022
@Dylan-DPC
Rollup merge of rust-lang#95805 - c410-f3r:meta-vars, r=petrochenkov
5092946 
Left overs of rust-lang#95761

These are just nits. Feel free to close this PR if all modifications are not worth merging.

* `#![feature(decl_macro)]` is not needed anymore in `rustc_expand`
* `tuple_impls` does not require `$Tuple:ident`. I guess it is there to enhance readability?

r? ```@petrochenkov```
@Dylan-DPC Dylan-DPC mentioned this pull request Apr 9, 2022
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@c410-f3r c410-f3r mentioned this pull request Apr 9, 2022
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bors added a commit to rust-lang-ci/rust that referenced this pull request Apr 9, 2022
@bors
Auto merge of rust-lang#95855 - Dylan-DPC:rollup-h45xmpw, r=Dylan-DPC
8bf93e9 
Rollup of 7 pull requests

Successful merges:

 - rust-lang#94794 (Clarify indexing into Strings)
 - rust-lang#95361 (Make non-power-of-two alignments a validity error in `Layout`)
 - rust-lang#95369 (Fix `x test src/librustdoc` with `download-rustc` enabled )
 - rust-lang#95805 (Left overs of rust-lang#95761)
 - rust-lang#95808 (expand: Remove `ParseSess::missing_fragment_specifiers`)
 - rust-lang#95817 (hide another #[allow] directive from a docs example)
 - rust-lang#95831 (Use bitwise XOR in to_ascii_uppercase)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
JohnTitor added a commit to JohnTitor/rust that referenced this pull request Jun 9, 2022
@JohnTitor
Rollup merge of rust-lang#95860 - c410-f3r:stabilize-meta, r=joshtrip…
41e40ec 
…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.
JohnTitor added a commit to JohnTitor/rust that referenced this pull request Jun 9, 2022
@JohnTitor
Rollup merge of rust-lang#95860 - c410-f3r:stabilize-meta, r=joshtrip…
afa2edb 
…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.
jonas-schievink
jonas-schievink reviewed Jul 8, 2022
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library/core/src/tuple.rs
Tuple9(A B C D E F G H I)
Tuple10(A B C D E F G H I J)
Tuple11(A B C D E F G H I J K)
Tuple12(A B C D E F G H I J K L)
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This change has caused rust-lang/rust-analyzer#12675

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I am not aware of the context within rust-analyzer but feel free to revert this commit if desired.

@c410-f3r c410-f3r mentioned this pull request Mar 21, 2024
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