rust-lang / rust-lang/rustfmt

Rustfmt add unwanted line wrap and indentation when formatting tuple method call

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A-tuples C-bug I-poor-formatting S-has-mcve
Dominant language
Rust
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Forks
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Avg merge
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Description

rustfmt 1.7.0-stable (82e1608d 2023-12-21) formats the tuple method call very weirdly when the tuple takes up several lines. It adds new line after ) and additional indent.

let x = (
    "some-very-long-first-argument-of-the-tuple",
    "second-argument",
)
    .into();

This produces really weird artefacts in some codebases. For example, some axum code:

return (
    StatusCode::CONFLICT,
    Html(format!("email {email} is already taken")),
)
    .into_response()

Expected formatting is the following:

let x = (
    "some-very-long-first-argument-of-the-tuple",
    "second-argument",
)
.into();
return (
    StatusCode::CONFLICT,
    Html(format!("email {email} is already taken")),
)
.into_response()

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running rustfmt 1.7.0-stable on the minimal tuple method-call example and the axum-style example from the report. Trace the formatting path for a multiline tuple followed by a method call. Done means both examples avoid the extra indentation while preserving the expected line break before the method call.

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
Active
Clarity
Mostly clear
Newbie friendliness
68/100

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