RS.CLIPPY.USELESS_VEC

Useless `vec!`

This checker is a Clippy lint created by The Rust Project Contributors. The documentation shown here is a copy of the original documentation for: useless_vec. Copyright ©2025 The Rust Team. All rights reserved.

What it does

Checks for usage of vec![..] when using [..] would be possible.

Why is this bad?

This is less efficient.

Example

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

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

Use instead:

foo(&[1, 2]);

Configuration

  • allow-useless-vec-in-tests: Whether useless_vec should ignore test functions or #[cfg(test)]

    (default: false)

  • too-large-for-stack: The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap

    (default: 200)