rust-lang / rust-lang/rust

closure rvalue not checked for WF allowing it to assume more implied bounds

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#123,312 2 comments 0 reactions 0 assignees View on GitHub

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A-borrow-checker A-closures A-NLL C-bug NLL-sound T-types
Dominant language
Rust
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Description

The following should not compile because the bound D: 'static is not satisfied in fn test:

struct Static<D: 'static>(Option<D>);

pub fn test<D>() {
    let _ = || {
        Static(None::<D>)
    };
}

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First steps

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  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 reproducer in the issue and verify that it currently compiles despite the missing D: 'static bound. Trace how closure rvalues are checked for well-formedness, then add a regression test demonstrating that test is rejected when the bound is unsatisfied.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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