Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::manual_pattern_char_comparison: this manual char comparison can be written more succinctly
What it meansChecks for manual char comparison in string patterns It is in the style group and warns by default.
What you see
warning: this manual char comparison can be written more succinctly --> main.rs:3:33 | 3 | "Hello World!".trim_end_matches(|c| c == '.' || c == ',' || c == '!' || c == '?'); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using an array of `char`: `['.', ',', '!', '?']` | = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_pattern_char_comparison = note: `#[warn(clippy::manual_pattern_char_comparison)]` 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 can be written more concisely using a char or an array of char. This is more readable and more optimized when comparing to only one char.
Code that works but is not idiomatic Rust. 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
"Hello World!".trim_end_matches(|c| c == '.' || c == ',' || c == '!' || c == '?');
Write this instead
"Hello World!".trim_end_matches(['.', ',', '!', '?']);
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::manual_pattern_char_comparison)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
manual_pattern_char_comparison = "allow"One run
cargo clippy -- -A clippy::manual-pattern-char-comparisonThe [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
msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml
Clippy's own documentation
What it does
Checks for manual char comparison in string patterns
Why is this bad?
This can be written more concisely using a char or an array of char.
This is more readable and more optimized when comparing to only one char.
Example
"Hello World!".trim_end_matches(|c| c == '.' || c == ',' || c == '!' || c == '?');
Use instead:
"Hello World!".trim_end_matches(['.', ',', '!', '?']);
Configuration
-
msrv: The minimum rust version that the project supports. Defaults to therust-versionfield inCargo.toml(default:
current version)
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- needless_returnunneeded `return` statement
- new_without_defaultChecks for public types with a pub fn new() -> Self method and no implementation of Default
- len_zeroChecks for getting the length of something via .len() just to compare to zero, and suggests using .is_empty() where applicable
- manual_next_backChecks for .rev().next() on a DoubleEndedIterator
- manual_non_exhaustiveChecks for manual implementations of the non-exhaustive pattern
- manual_ok_orthis pattern reimplements `Option::ok_or`
- manual_range_containsmanual `Range::contains` implementation
- manual_repeat_nthis `repeat().take()` can be written more concisely
- manual_rotatethere is no need to manually implement bit rotation
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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