Clippy lint · Pedantic · checked with Clippy 0.1.99

clippy::manual_assert_eq: used `assert!` with an equality comparison

What it meansChecks for assert! and debug_assert! that consist of only an (in)equality check It is in the pedantic group and off by default.

What you see

warning: used `assert!` with an equality comparison
 --> main.rs:3:1
  |
3 | assert!(2 * 2 == 4);
  | ^^^^^^^^^^^^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_assert_eq
  = note: `-W clippy::manual-assert-eq` implied by `-W clippy::pedantic`
help: replace it with `assert_eq!(..)`
  |
3 - assert!(2 * 2 == 4);
3 + assert_eq!(2 * 2, 4);
  |

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?

assert_{eq,ne}! and debug_assert_{eq,ne}! achieves the same goal, and provides some additional debug information

Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.

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

assert!(2 * 2 == 4);
assert!(2 * 2 != 5);
debug_assert!(2 * 2 == 4);
debug_assert!(2 * 2 != 5);

Write this instead

assert_eq!(2 * 2, 4);
assert_ne!(2 * 2, 5);
debug_assert_eq!(2 * 2, 4);
debug_assert_ne!(2 * 2, 5);

Turn it off, or on

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

Whole crate (Cargo.toml)

[lints.clippy]
manual_assert_eq = "warn"

In code

#![warn(clippy::manual_assert_eq)]

One run

cargo clippy -- -W clippy::manual-assert-eq

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.

Pedanticgroup

allowdefault level

yesfixed by cargo clippy --fix

1.97.0added in Rust

Clippy's own documentation

What it does

Checks for assert! and debug_assert! that consist of only an (in)equality check

Why is this bad?

assert_{eq,ne}! and debug_assert_{eq,ne}! achieves the same goal, and provides some additional debug information

Example

assert!(2 * 2 == 4);
assert!(2 * 2 != 5);
debug_assert!(2 * 2 == 4);
debug_assert!(2 * 2 != 5);

Use instead:

assert_eq!(2 * 2, 4);
assert_ne!(2 * 2, 5);
debug_assert_eq!(2 * 2, 4);
debug_assert_ne!(2 * 2, 5);

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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