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Detect when ? is being called on a type *after* .unwrap or .expect was called on a Result or Option #127345

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estebank opened this issue Jul 4, 2024 · 0 comments
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A-diagnostics Area: Messages for errors, warnings, and lints A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` D-newcomer-roadblock Diagnostics: Confusing error or lint; hard to understand for new users. D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. P-low Low priority T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@estebank
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estebank commented Jul 4, 2024

The following code

fn foo() -> Option<usize> {
    let x = Some(42).unwrap()?;
    x
}

currently emits

error[E0277]: the `?` operator can only be applied to values that implement `Try`
 --> src/lib.rs:2:13
  |
2 |     let x = Some(42).unwrap()?;
  |             ^^^^^^^^^^^^^^^^^^ the `?` operator cannot be applied to type `{integer}`
  |
  = help: the trait `Try` is not implemented for `{integer}`

but it should suggest removing the .unwrap().

Inspired by https://x.com/jonasfovea/status/1808961128812183774

@estebank estebank added A-diagnostics Area: Messages for errors, warnings, and lints P-low Low priority T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` D-newcomer-roadblock Diagnostics: Confusing error or lint; hard to understand for new users. D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. labels Jul 4, 2024
@chenyukang chenyukang assigned chenyukang and unassigned chenyukang Jul 5, 2024
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Labels
A-diagnostics Area: Messages for errors, warnings, and lints A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` D-newcomer-roadblock Diagnostics: Confusing error or lint; hard to understand for new users. D-terse Diagnostics: An error or lint that doesn't give enough information about the problem at hand. P-low Low priority T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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