Simplify if-let-Some-else-None using question mark operator

[qsantos]

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.