Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::question_mark: Checks for expressions that could be replaced by the ? operator
What it meansChecks for expressions that could be replaced by the ? operator. It is in the style group and warns by default.
Does it matter?
Using the ? operator is shorter and more idiomatic.
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 option.is_none() {
return None;
}
Write this instead
option?;
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::question_mark)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
question_mark = "allow"One run
cargo clippy -- -A clippy::question-markThe [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
msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml
Clippy's own documentation
What it does
Checks for expressions that could be replaced by the ? operator.
Why is this bad?
Using the ? operator is shorter and more idiomatic.
Example
if option.is_none() {
return None;
}
Could be written:
option?;
Configuration
-
msrv: The minimum rust version that the project supports. Defaults to therust-versionfield inCargo.toml(default:
current version)
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
- println_empty_stringempty string literal in `println!`
- ptr_argThis lint checks for function arguments of type &String, &Vec, &PathBuf, and Cow<_>
- ptr_equse `std::ptr::eq` when comparing raw pointers
- redundant_closureChecks for closures which just call another function where the function can be called directly
- redundant_field_namesredundant field names in struct initialization
- redundant_patternthe `y @ _` pattern can be written as just `y`
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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