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[macro_metavar_expr] Add tests to ensure the feature requirement #95764

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merged 1 commit into from
Apr 9, 2022
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[macro_metavar_expr] Add tests to ensure the feature requirement #95764

merged 1 commit into from
Apr 9, 2022

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@c410-f3r c410-f3r commented Apr 7, 2022

These tests should have been added in the initial implementation they were unintentionally forgotten

cc #83527
r? @petrochenkov

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Apr 7, 2022
@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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@bors r+ rollup

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bors commented Apr 7, 2022

📌 Commit 5974c18 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#95764 - c410-f3r:metavar-test, r=petrochenkov
cfa8483 
[macro_metavar_expr] Add tests to ensure the feature requirement

These tests should have been added in the initial implementation they were unintentionally forgotten

cc rust-lang#83527
r? `@petrochenkov`
@Dylan-DPC Dylan-DPC mentioned this pull request Apr 8, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Apr 8, 2022
@Dylan-DPC
Rollup merge of rust-lang#95764 - c410-f3r:metavar-test, r=petrochenkov
00c288c 
[macro_metavar_expr] Add tests to ensure the feature requirement

These tests should have been added in the initial implementation they were unintentionally forgotten

cc rust-lang#83527
r? ``@petrochenkov``
@Dylan-DPC Dylan-DPC mentioned this pull request Apr 8, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Apr 8, 2022
@Dylan-DPC
Rollup merge of rust-lang#95764 - c410-f3r:metavar-test, r=petrochenkov
7328ae9 
[macro_metavar_expr] Add tests to ensure the feature requirement

These tests should have been added in the initial implementation they were unintentionally forgotten

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 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#95835 - Dylan-DPC:rollup-l5mf2ad, r=Dylan-DPC
4bb685e 
Rollup of 8 pull requests

Successful merges:

 - rust-lang#90066 (Add new ThinBox type for 1 stack pointer wide heap allocated trait objects)
 - rust-lang#95374 (assert_uninit_valid: ensure we detect at least arrays of uninhabited types)
 - rust-lang#95599 (Strict provenance lints)
 - rust-lang#95751 (Don't report numeric inference ambiguity when we have previous errors)
 - rust-lang#95764 ([macro_metavar_expr] Add tests to ensure the feature requirement)
 - rust-lang#95787 (reword panic vs result section to remove recoverable vs unrecoverable framing)
 - rust-lang#95797 (Remove explicit delimiter token trees from `Delimited`.)
 - rust-lang#95804 (rustdoc: Fix empty doc comment with backline ICE)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 0051301 into rust-lang:master Apr 9, 2022
@rustbot rustbot added this to the 1.62.0 milestone Apr 9, 2022
@c410-f3r c410-f3r mentioned this pull request Apr 9, 2022
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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.
@c410-f3r c410-f3r mentioned this pull request Mar 21, 2024
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