Clippy lints / Complexity
Clippy lint · Complexity · checked with Clippy 0.1.99
clippy::filter_map_identity: Checks for usage of filter_map(|x| x)
What it meansChecks for usage of filter_map(|x| x). It is in the complexity group and warns by default.
Does it matter?
Readability, this can be written more concisely by using flatten.
Code that does something simple in a complicated way. 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
iter.filter_map(|x| x);
Write this instead
iter.flatten();
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::filter_map_identity)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
filter_map_identity = "allow"One run
cargo clippy -- -A clippy::filter-map-identityThe [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 usage of filter_map(|x| x).
Why is this bad?
Readability, this can be written more concisely by using flatten.
Example
iter.filter_map(|x| x);
Use instead:
iter.flatten();
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- too_many_argumentsChecks for functions with too many parameters
- clone_on_copyusing `clone` on type `u64` which implements the `Copy` trait
- type_complexityChecks for types used in structs, parameters and let declarations above a certain complexity threshold
- explicit_writeChecks for usage of write!() / writeln()! which can be replaced with (e)print!() / (e)println!()
- extra_unused_lifetimesthis lifetime isn't used in the function definition
- extra_unused_type_parametersChecks for type parameters in generics that are never used anywhere else
- filter_nextChecks for usage of _.filter(_).next()
- flat_map_identityChecks for usage of flat_map(|x| x)
- get_last_with_lenaccessing last element with `x.get(x.len() - 1)`
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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