RS.CLIPPY.ABSURD_EXTREME_COMPARISONS

A comparison with a maximum or minimum value that is always true or false

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

What it does

Checks for comparisons where one side of the relation is either the minimum or maximum value for its type and warns if it involves a case that is always true or always false. Only integer and boolean types are checked.

Why is this bad?

An expression like min <= x may misleadingly imply that it is possible for x to be less than the minimum. Expressions like max < x are probably mistakes.

Known problems

For usize the size of the current compile target will be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such a comparison to detect target pointer width will trigger this lint. One can use mem::sizeof and compare its value or conditional compilation attributes like #[cfg(target_pointer_width = "64")] .. instead.

Example

let vec: Vec<isize> = Vec::new();
if vec.len() <= 0 {}
if 100 > i32::MAX {}