Clippy lints / Complexity
Clippy lint · Complexity · checked with Clippy 0.1.99
clippy::needless_ifs: Checks for empty if branches with no else branch
What it meansChecks for empty if branches with no else branch. It is in the complexity group and warns by default.
Does it matter?
It can be entirely omitted, and often the condition too.
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
if really_expensive_condition(&i) {}
if really_expensive_condition_with_side_effects(&mut i) {}
Write this instead
// <omitted>
really_expensive_condition_with_side_effects(&mut i);
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::needless_ifs)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
needless_ifs = "allow"One run
cargo clippy -- -A clippy::needless-ifsThe [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 empty if branches with no else branch.
Why is this bad?
It can be entirely omitted, and often the condition too.
Known issues
This will usually only suggest to remove the if statement, not the condition. Other lints
such as no_effect will take care of removing the condition if it’s unnecessary.
Example
if really_expensive_condition(&i) {}
if really_expensive_condition_with_side_effects(&mut i) {}
Use instead:
// <omitted>
really_expensive_condition_with_side_effects(&mut i);
Past names
- needless_if
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
- needless_boolChecks for expressions of the form if c { true } else { false } (or vice versa) and suggests using the condition directly
- needless_bool_assignChecks for expressions of the form if c { x = true } else { x = false } (or vice versa) and suggest assigning the variable directly from the condition
- needless_borrowed_referencethis pattern takes a reference on something that is being dereferenced
- needless_lifetimesthe following explicit lifetimes could be elided: 'a
- needless_matchChecks for unnecessary match or match-like if let returns for Option and Result when function signatures are the same
- needless_option_as_derefderefed type is same as origin
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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Related lintclippy::too_many_argumentsChecks for functions with too many parametersRead it next →Did this answer your question?