Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::single_match: Checks for matches with a single arm where an if let will usually suffice. This intentionally does not lint if there are comments inside of the other arm, so as to allow the user to document why having another explicit pattern with an empty body is necessary, or because the comments need to be preserved for other reasons
What it meansChecks for matches with a single arm where an if let will usually suffice. This intentionally does not lint if there are comments inside of the other arm, so as to allow the user to document why having another explicit pattern with an empty body is necessary, or because the comments need to be preserved for other reasons. It is in the style group and warns by default.
Does it matter?
Just readability - if let nests less than a match.
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
match x {
Some(ref foo) => bar(foo),
_ => (),
}
Write this instead
if let Some(ref foo) = x {
bar(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::single_match)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
single_match = "allow"One run
cargo clippy -- -A clippy::single-matchThe [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 matches with a single arm where an if let
will usually suffice.
This intentionally does not lint if there are comments inside of the other arm, so as to allow the user to document why having another explicit pattern with an empty body is necessary, or because the comments need to be preserved for other reasons.
Why is this bad?
Just readability - if let nests less than a match.
Example
match x {
Some(ref foo) => bar(foo),
_ => (),
}
Use instead:
if let Some(ref foo) = x {
bar(foo);
}
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
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All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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