Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::redundant_pattern: the `y @ _` pattern can be written as just `y`
What it meansChecks for patterns in the form name @ _. It is in the style group and warns by default.
What you see
warning: the `y @ _` pattern can be written as just `y` --> main.rs:5:5 | 5 | y @ _ => (), | ^^^^^ help: try: `y` | = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#redundant_pattern = note: `#[warn(clippy::redundant_pattern)]` 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?
It’s almost always more readable to just use direct bindings.
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
match v {
Some(x) => (),
y @ _ => (),
}
Write this instead
match v {
Some(x) => (),
y => (),
}
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::redundant_pattern)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
redundant_pattern = "allow"One run
cargo clippy -- -A clippy::redundant-patternThe [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.
Clippy's own documentation
What it does
Checks for patterns in the form name @ _.
Why is this bad?
It’s almost always more readable to just use direct bindings.
Example
match v {
Some(x) => (),
y @ _ => (),
}
Use instead:
match v {
Some(x) => (),
y => (),
}
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
- question_markChecks for expressions that could be replaced by the ? operator
- redundant_closureChecks for closures which just call another function where the function can be called directly
- redundant_field_namesredundant field names in struct initialization
- redundant_pattern_matchingLint for redundant pattern matching over Result, Option, std::task::Poll, std::net::IpAddr or bools
- redundant_static_lifetimesconstants have by default a `'static` lifetime
- result_map_or_into_optionChecks for usage of _.map_or(None, Some)
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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