Open
Description
Consider the code below.
pub fn f(x: Option<u32>) -> Option<u32> {
if let Some(x) = x {
dbg!(x);
Some(x * 2)
} else {
None
}
}Standard Clippy produces no warning. More exhaustive options suggest code that is no significantly better:
$ cargo clippy --all -- -W clippy::all -W clippy::nursery
error: use Option::map_or instead of an if let/else
--> src/lib.rs:2:5
|
2 | / if let Some(x) = x {
3 | | dbg!(x);
4 | | Some(x * 2)
5 | | } else {
6 | | None
7 | | }
| |_____^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#option_if_let_else
= note: `-D clippy::option-if-let-else` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::option_if_let_else)]`
help: try
|
2 ~ x.map_or(None, |x| {
3 + dbg!(x);
4 + Some(x * 2)
5 + })
|
However, the code can be written with less nesting, using the question mark operator:
pub fn f(x: Option<u32>) -> Option<u32> {
let x = x?;
dbg!(x);
Some(x * 2)
}Note that Clippy does suggest that for the code below:
pub fn f(x: Option<u32>) -> Option<u32> {
let Some(x) = x else {
return None;
};
dbg!(x);
Some(x * 2)
}error: this `let...else` may be rewritten with the `?` operator
--> src/lib.rs:2:5
|
2 | / let Some(x) = x else {
3 | | return None;
4 | | };
| |______^ help: replace it with: `let x = x?;`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#question_mark
= note: `-D clippy::question-mark` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(clippy::question_mark)]`
This pattern is particularly frequent when implementing iterators.