Don't trigger unwrap_used or expect_used on uninhabited Err#16712
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samueltardieu wants to merge 1 commit intorust-lang:masterfrom
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Don't trigger unwrap_used or expect_used on uninhabited Err#16712samueltardieu wants to merge 1 commit intorust-lang:masterfrom
unwrap_used or expect_used on uninhabited Err#16712samueltardieu wants to merge 1 commit intorust-lang:masterfrom
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r? @Jarcho rustbot has assigned @Jarcho. Use Why was this reviewer chosen?The reviewer was selected based on:
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When the `Err` variant is a known uninhabited type, there is no point in complaining when `.unwrap()` or `.expect(…)` are used, as they cannot fail. One alternative would be to complain and suggest using `let Ok(_) = _;` which wouldn't fail either, but it may not integrate well into the code flow.
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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| #[derive(Clone, Debug)] | ||
| struct S { | ||
| x: std::convert::Infallible, | ||
| y: u32, | ||
| } | ||
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| fn f(s: Result<String, S>) { | ||
| // Check that the compiler sees the `S` type as uninhabited (because of its `x` field) | ||
| let Ok(_) = s.clone(); | ||
| // Do not lint: `s` is necessarily `Ok` as shown above | ||
| _ = s.clone().unwrap(); | ||
| _ = s.clone().expect("uninhabited struct is inhabited"); | ||
| } |
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A test with an invisibly uninhabited type should also be included.
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When the
Errvariant is a known uninhabited type, there is no point in complaining when.unwrap()or.expect(…)are used, as they cannot fail.One alternative would be to complain and suggest using
let Ok(_) = _;which wouldn't fail either, but it may not integrate well into the code flow.changelog: [
unwrap_used] [expect_used]: do not warn onResulttypes whoseErrvariant is visibly uninhabited.