Clippy lints / Pedantic
Clippy lint · Pedantic · checked with Clippy 0.1.99
clippy::if_not_else: Checks for usage of ! or != in an if condition with an else branch
What it meansChecks for usage of ! or != in an if condition with an else branch. It is in the pedantic group and off by default.
Does it matter?
Negations reduce the readability of statements.
Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.
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 !v.is_empty() {
a()
} else {
b()
}
Write this instead
if v.is_empty() {
b()
} else {
a()
}
Turn it off, or on
It is off by default. To use it, set it to warn or deny:
Whole crate (Cargo.toml)
[lints.clippy]
if_not_else = "warn"In code
#![warn(clippy::if_not_else)]One run
cargo clippy -- -W clippy::if-not-elseThe [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 ! or != in an if condition with an
else branch.
Why is this bad?
Negations reduce the readability of statements.
Example
if !v.is_empty() {
a()
} else {
b()
}
Could be written:
if v.is_empty() {
b()
} else {
a()
}
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
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- must_use_candidateChecks for public functions that have no #[must_use] attribute, but return something not already marked must-use, have no mutable arg and mutate no statics
- fn_params_excessive_boolsChecks for excessive use of bools in function declarations
- format_collectuse of `format!` to build up a string from an iterator
- format_push_string`format!(..)` appended to existing `String`
- ignore_without_reasonChecks for ignored tests without messages
- ignored_unit_patternsmatching over `()` is more explicit
- implicit_cloneimplicitly cloning a `Vec` by calling `to_vec` on its dereferenced type
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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