rust-lang / rust-lang/rust-clippy
`.as_ref().map(|x| *x)` is no longer warned
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@Jacherr is already working on this.
Since Jun 2, 2024.
C-bug
I-false-negative
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- Rust
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Description
Summary
We used to lint on Some(1).as_ref().map(|x| *x), but no longer do. The interaction between the two lints useless_asref and map_clone is important here.
Some more context (where this was found and probably for why this is): https://github.com/rust-lang/rust-clippy/pull/12136#discussion_r1451562174.
Lint Name
map_clone / useless_asref
Reproducer
I tried this code:
fn main() {
Some(1).as_ref().map(|x| *x);
Some(1).as_ref().map(|&x| x);
}
I expected to see this happen:
warning: you are using an explicit closure for copying elements
--> src/main.rs:2:3
|
2 | Some(1).as_ref().map(|x| *x);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `Some(1).as_ref().copied()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#map_clone
= note: `#[warn(clippy::map_clone)]` on by default
warning: you are using an explicit closure for copying elements
--> src/main.rs:3:3
|
3 | Some(1).as_ref().map(|&x| x);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `copied` method: `Some(1).as_ref().copied()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#map_clone
Instead, this happened:
no warnings
Version
commit a71211d0b52c01f1b37fe544e0e13fd1bdc31979 (Jan 12)
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