rust-lang / rust-lang/rustfmt

rustfmt removes `for<T>`

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I-poor-formatting P-low
Dominant language
Rust
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Description

fn foo()
where
    for<T> T: Clone,
{
}

fn bar<T>()
where
    T: for<U> Clone,
{
}

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=677e24af49ee0202ec774403628637bf

Formatted with rustfmt, it becomes:

fn foo()
where
    T: Clone,
{
}

fn bar<T>()
where
    T: Clone,
{
}

for<T> isn't valid Rust, but removing it looks wrong. However, feel free to close if you disagree.

Contributor guide

Open the contributing guide

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 with the Rust Playground reproducer in the issue and inspect rustfmt's handling of the two where-clause examples. The fix is done when formatting preserves the for<T> binders rather than removing them, with coverage for both shown cases.

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
35/100

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