clippy::useless_vec: useless use of `vec!`

What you see

warning: useless use of `vec!`
 --> main.rs:5:5
  |
5 | foo(&vec![1, 2]);
  |     ^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2]`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#useless_vec
  = note: `#[warn(clippy::useless_vec)]` 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?

This is less efficient.

Code that could be written to run faster. 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

fn foo(_x: &[u8]) {}

foo(&vec![1, 2]);

Write this instead

foo(&[1, 2]);

Turn it off, or on

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

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

[lints.clippy]
useless_vec = "allow"

cargo clippy -- -A clippy::useless-vec

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.

Settings in clippy.toml

• allow-useless-vec-in-tests: Whether useless_vec should ignore test functions or #[cfg(test)]
• too-large-for-stack: The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap