rust-lang/rust-clippy
Voir sur GitHub`unnecessary_lazy_evaluations`: lint `{Option,Result}::map_or_else`
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#15 829 ouverte le 6 oct. 2025
C-enhancementgood first issue
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- (10 406 stars)
- Métriques de merge PR
- (Merge moyen 16j 6h) (79 PRs mergées en 30 j)
Description
Description
None of the following currently get linted:
(EDIT: this used to include map_or, but as the comments below rightfully say, its closure can't actually be made eager)
#![allow(unused)]
#![warn(clippy::unnecessary_lazy_evaluations)]
fn main() {
let o = Some(42);
o.map_or_else(|| 42, |_| 42);
let r: Result<i32, i32> = Ok(42);
r.map_or_else(|_| 42, |_| 42);
}
It would be cool if they did:
#![allow(unused)]
#![warn(clippy::unnecessary_lazy_evaluations)]
fn main() {
let o = Some(42);
o.map_or(42, |_| 42);
let r: Result<i32, i32> = Ok(42);
r.map_or(42, |_| 42);
}
Version
rustc 1.92.0-nightly (839222065 2025-10-05)
binary: rustc
commit-hash: 839222065a44ac21c15df68ed2f2f3c0127b0b8e
commit-date: 2025-10-05
host: x86_64-unknown-linux-gnu
release: 1.92.0-nightly
LLVM version: 21.1.2
Additional Labels
@rustbot label C-enhancement "good first issue"