rust-lang / rust-lang/rustfmt

inconsistent indents on function calls with closure arguments

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A-closures I-poor-formatting
Dominant language
Rust
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Description

Edit (simplified):

Output of rustfmt on nightly-2024-03-08:

fn main() {
    app.with_state()
        .layer(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(
        |foo: &Xxxxxxxxx| macroxxxx!(??xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx),
    ));
}

Expected:

fn main() {
    app.with_state()
        .layer(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(|foo: &Xxxxxxxxx| {
            macroxxxx!(??xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)
        }));
}
original report

This code:

fn main() {
    let app = app
        .with_state(build_schema().await)
        .layer(TraceLayer::new_for_http().make_span_with(
            |req: &Request<_>| info_span!("req", method=?req.method(), path=req.uri().to_string()),
        ));
}

formats to:

❮ rustfmt +nightly-2024-03-08 b.rs --emit stdout
/tmp/ktmp/SgB/b.rs:

fn main() {
    let app =
        app.with_state(build_schema().await)
            .layer(TraceLayer::new_for_http().make_span_with(
            |req: &Request<_>| info_span!("req", method=?req.method(), path=req.uri().to_string()),
        ));
}

I think leaving the original code is fine. Or maybe It's ideal to indent the argument one more block like this:

fn main() {
    let app =
        app.with_state(build_schema().await)
            .layer(TraceLayer::new_for_http().make_span_with(
                |req: &Request<_>| info_span!("req", method=?req.method(), path=req.uri().to_string()),
            ));
}

because rustfmt emits like so if the argument was normal function call. For example:

❯ rustfmt +nightly-2024-03-08 a.rs --emit stdout
/tmp/ktmp/SgB/a.rs:

fn main() {
    let app =
        app.with_state(build_schema().await)
            .layer(TraceLayer::new_for_http().make_span_with(
                sooooooooooooooooooooooooooooooooooooooo_long_function_call_here(foo, bar, baz),
            ));
}

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the report with the rustfmt command and the closure-argument examples shown in the issue. Compare formatting for closure arguments with the normal function-call example, then verify that the output matches the expected indentation without regressing the existing formatting behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
48/100

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