clippy::clear_with_drain: `drain` used to clear a `Vec`

What you see

warning: `drain` used to clear a `Vec`
 --> main.rs:4:3
  |
4 | v.drain(..);
  |   ^^^^^^^^^ help: try: `clear()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#clear_with_drain
  = note: `-W clippy::clear-with-drain` implied by `-W clippy::nursery`

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?

This creates an unnecessary iterator that is dropped immediately. Calling .clear() also makes the intent clearer.

New lints still being finished. Off by default and may have false positives.

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 mut v = vec![1, 2, 3];
v.drain(..);

Write this instead

let mut v = vec![1, 2, 3];
v.clear();

Turn it off, or on

It is off by default. To use it, set it to warn or deny:

[lints.clippy]
clear_with_drain = "warn"

#![warn(clippy::clear_with_drain)]

cargo clippy -- -W clippy::clear-with-drain

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.