rust-lang / rust-lang/rust-analyzer

"Unwrap `Result` return type" shouldn't trigger in trait impls

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#13,560 1 comment 0 reactions 0 assignees View on GitHub

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A-assists C-bug S-actionable
Dominant language
Rust
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Description

trait Tr {
    fn f() -> Result<(), ()>;
}

impl Tr for () {
    fn f() -> $0Result<(), ()> {
        todo!()
    }
}

This offers the "Unwrap Result return type", which removes the return type here, but this is wrong in a trait impl if the trait isn't also modified (which requires fixing up every impl of it).

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First steps

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Research direction

Start with the "Unwrap Result return type" assist and reproduce the trait and impl example from the issue. Trace how the assist determines whether it can remove the return type, then verify that it is not offered in the trait implementation unless the trait declaration is also safely updated.

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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