Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::redundant_closure: Checks for closures which just call another function where the function can be called directly
What it meansChecks for closures which just call another function where the function can be called directly. unsafe functions, calls where types get adjusted or where the callee is marked #[track_caller] are ignored. It is in the style group and warns by default.
Does it matter?
Needlessly creating a closure adds code for no benefit and gives the optimizer more work.
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
xs.map(|x| foo(x))
Write this instead
// where `foo(_)` is a plain function that takes the exact argument type of `x`.
xs.map(foo)
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_closure)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
redundant_closure = "allow"One run
cargo clippy -- -A clippy::redundant-closureThe [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 closures which just call another function where
the function can be called directly. unsafe functions, calls where types
get adjusted or where the callee is marked #[track_caller] are ignored.
Why is this bad?
Needlessly creating a closure adds code for no benefit and gives the optimizer more work.
Example
xs.map(|x| foo(x))
Use instead:
// where `foo(_)` is a plain function that takes the exact argument type of `x`.
xs.map(foo)
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
- ptr_argThis lint checks for function arguments of type &String, &Vec, &PathBuf, and Cow<_>
- ptr_equse `std::ptr::eq` when comparing raw pointers
- question_markChecks for expressions that could be replaced by the ? operator
- redundant_field_namesredundant field names in struct initialization
- redundant_patternthe `y @ _` pattern can be written as just `y`
- redundant_pattern_matchingLint for redundant pattern matching over Result, Option, std::task::Poll, std::net::IpAddr or bools
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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