clippy::some_filter: use of `Some(x).filter(|_| predicate)`

What you see

warning: use of `Some(x).filter(|_| predicate)`
 --> main.rs:4:1
  |
4 | Some(0).filter(|_| x);
  | ^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this change will alter the order in which the condition and the value are evaluated
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#some_filter
  = note: `#[warn(clippy::some_filter)]` on by default
help: consider using `bool::then_some` instead
  |
4 - Some(0).filter(|_| x);
4 + x.then_some(0);
  |

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

Readability, this can be written more concisely as predicate.then_some(x).

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:

Flagged

let x = false;
Some(0).filter(|_| x);

Write this instead

let x = false;
x.then_some(0);

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

#[allow(clippy::some_filter)]
fn my_function() { /* ... */ }

[lints.clippy]
some_filter = "allow"

cargo clippy -- -A clippy::some-filter

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.