clippy::needless_option_take: called `Option::take()` on a temporary value

What you see

warning: called `Option::take()` on a temporary value
 --> main.rs:4:1
  |
4 | x.as_ref().take();
  | ^^^^^^^^^^-------
  |           |
  |           help: remove
  |
  = note: `as_ref` creates a temporary value, so calling take() has no effect
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#needless_option_take
  = note: `#[warn(clippy::needless_option_take)]` on by default

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?

Redundant code. take writes None to its argument. In this case the modification is useless as it’s a temporary that cannot be read from afterwards.

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

How to fix it

Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.

Flagged

let x = Some(3);
x.as_ref().take();

Write this instead

let x = Some(3);
x.as_ref();

Turn it off, or on

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

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

[lints.clippy]
needless_option_take = "allow"

cargo clippy -- -A clippy::needless-option-take

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.