rust-lang / rust-lang/rustfmt

rustfmt deletes comment after arrow in Fn type

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#6,473 3 comments 0 reactions 0 assignees View on GitHub

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A-comments C-bug I-unexpectedly-removes-code
Dominant language
Rust
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Forks
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Avg merge
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Merged PRs (30d)
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Description

Input:

fn foo(f: &dyn Fn(i32) -> /*result*/ i32)  {
}

after rustfmt becomes

fn foo(f: &dyn Fn(i32) -> i32) {}
Expected

Preserve /*result*/ comment

Observed

Comment deleted.

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Research direction

Reproduce the issue with the provided Fn type snippet and inspect rustfmt's handling of comments after the arrow in function types. Trace the formatting path for this syntax, then verify that running rustfmt preserves the /result/ comment.

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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