Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::collapsible_if: Checks for nested if statements which can be collapsed by &&-combining their conditions
What it meansChecks for nested if statements which can be collapsed by &&-combining their conditions. It is in the style group and warns by default.
Does it matter?
Each if-statement adds one level of nesting, which makes code look more complex than it really is.
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
if x {
if y {
// …
}
}
Write this instead
if 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::collapsible_if)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
collapsible_if = "allow"One run
cargo clippy -- -A clippy::collapsible-ifThe [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
lint-commented-code: Whether collapsible if and else if chains are linted if they contain comments inside the parts that would be collapsed.
Clippy's own documentation
What it does
Checks for nested if statements which can be collapsed
by &&-combining their conditions.
Why is this bad?
Each if-statement adds one level of nesting, which
makes code look more complex than it really is.
Example
if x {
if y {
// …
}
}
Use instead:
if x && y {
// …
}
Configuration
-
lint-commented-code: Whether collapsibleifandelse ifchains are linted if they contain comments inside the parts that would be collapsed.(default:
false)
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
- chars_next_cmpyou should use the `starts_with` method
- chunks_exact_to_as_chunksusing `chunks_exact` with a constant chunk size
- cmp_nullThis lint checks for equality comparisons with ptr::null or ptr::null_mut
- collapsible_matchthis `match` can be collapsed into the outer `match`
- comparison_to_emptyChecks for comparing to an empty slice such as "" or [], and suggests using .is_empty() where applicable
- default_instead_of_iter_empty`std::iter::empty()` is the more idiomatic way
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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