rust-lang / rust-lang/rustfmt

Non-idempotent formatting for empty statment.

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A-statements C-bug I-non-idempotency
Dominant language
Rust
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Avg merge
2d 13h
Merged PRs (30d)
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Description

Input code:

fn format_this() {
    let foo = {;()};
}

After first format:

fn format_this() {
    let foo = {
        ()
    };
}

After second format:

fn format_this() {
    let foo = { () };
}

Observed on play.rust-lang.org using 1.8.0-nightly (2026-02-03 366a1b93e7). link

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Research direction

Reproduce the example in the linked play.rust-lang.org session using the reported nightly toolchain and format the input twice. Trace the rustfmt formatting path for an empty statement inside a block, then add or update coverage for the example. Done means formatting the result repeatedly produces identical output.

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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