rust-lang / rust-lang/rustfmt

Failing when macro has `%` in it, e.g. Tracing

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A-macros P-low
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Rust
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Description

Here's a sample code:

            TraceLayer::new_for_http()
                .make_span_with(|request: &Request<Body>| {
                    tracing::info_span!(
                        "request",
                        method = %request.method(),
                        uri = %request.uri(), status = tracing::field::Empty,
                        latency = tracing::field::Empty,
                    )
                })

this uses a macro from tracing to create the Span. However the % in there makes rustfmt fail.

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Research direction

Reproduce the failure with the provided tracing::info_span! example, focusing on the % field expressions inside the macro. Trace rustfmt's macro-formatting path and add coverage for this input; done means rustfmt formats the sample without failing.

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
45/100

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