RS.CLIPPY.MANUAL_IS_POWER_OF_TWO

Manually reimplementing `is_power_of_two`

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

What it does

Checks for expressions like x.count_ones() == 1 or x & (x - 1) == 0, with x and unsigned integer, which may be manual reimplementations of x.is_power_of_two().

Why is this bad?

Manual reimplementations of is_power_of_two increase code complexity for little benefit.

Example

let a: u32 = 4;
let result = a.count_ones() == 1;

Use instead:

let a: u32 = 4;
let result = a.is_power_of_two();

Configuration

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

(default: current version)