rust/compiler/rustc_lint
bors 8cc6f34653 Auto merge of #119427 - dtolnay:maccall, r=compiler-errors
Fix, document, and test parser and pretty-printer edge cases related to braced macro calls

_Review note: this is a deceptively small PR because it comes with 145 lines of docs and 196 lines of tests, and only 25 lines of compiler code changed. However, I recommend reviewing it 1 commit at a time because much of the effect of the code changes is non-local i.e. affecting code that is not visible in the final state of the PR. I have paid attention that reviewing the PR one commit at a time is as easy as I can make it. All of the code you need to know about is touched in those commits, even if some of those changes disappear by the end of the stack._

This is a follow-up to https://github.com/rust-lang/rust/pull/119105. One case that is not relevant to `-Zunpretty=expanded`, but which came up as I'm porting #119105 and #118726 into `syn`'s printer and `prettyplease`'s printer where it **is** relevant, and is also relevant to rustc's `stringify!`, is statement boundaries in the vicinity of braced macro calls.

Rustc's AST pretty-printer produces invalid syntax for statements that begin with a braced macro call:

```rust
macro_rules! stringify_item {
    ($i:item) => {
        stringify!($i)
    };
}

macro_rules! repro {
    ($e:expr) => {
        stringify_item!(fn main() { $e + 1; })
    };
}

fn main() {
    println!("{}", repro!(m! {}));
}
```

**Before this PR:** output is not valid Rust syntax.

```console
fn main() { m! {} + 1; }
```

```console
error: leading `+` is not supported
 --> <anon>:1:19
  |
1 | fn main() { m! {} + 1; }
  |                   ^ unexpected `+`
  |
help: try removing the `+`
  |
1 - fn main() { m! {} + 1; }
1 + fn main() { m! {}  1; }
  |
```

**After this PR:** valid syntax.

```console
fn main() { (m! {}) + 1; }
```
2024-05-12 04:18:20 +00:00
..
src Auto merge of #119427 - dtolnay:maccall, r=compiler-errors 2024-05-12 04:18:20 +00:00
Cargo.toml Remove useless smallvec dependency in rustc_lint::non_local_def 2024-03-07 07:54:15 +01:00
messages.ftl Adjust #[macro_export]/doctest help suggestion for non_local_defs lint 2024-05-01 16:57:20 +02:00