Clippy lints / Nursery
Clippy lint · Nursery · checked with Clippy 0.1.99
clippy::iter_with_drain: Checks for usage of .drain(..) on Vec and VecDeque for iteration
What it meansChecks for usage of .drain(..) on Vec and VecDeque for iteration. It is in the nursery group and off by default.
Does it matter?
.into_iter() is simpler with better performance.
New lints still being finished. Off by default and may have false positives.
How to fix it
Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:
Flagged
let mut foo = vec![0, 1, 2, 3];
let bar: HashSet<usize> = foo.drain(..).collect();
Write this instead
let foo = vec![0, 1, 2, 3];
let bar: HashSet<usize> = foo.into_iter().collect();
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]
iter_with_drain = "warn"In code
#![warn(clippy::iter_with_drain)]One run
cargo clippy -- -W clippy::iter-with-drainThe [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 .drain(..) on Vec and VecDeque for iteration.
Why is this bad?
.into_iter() is simpler with better performance.
Example
let mut foo = vec![0, 1, 2, 3];
let bar: HashSet<usize> = foo.drain(..).collect();
Use instead:
let foo = vec![0, 1, 2, 3];
let bar: HashSet<usize> = foo.into_iter().collect();
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- redundant_cloneChecks for a redundant clone() (and its relatives) which clones an owned value that is going to be dropped without further use
- imprecise_flopscube-root of a number can be computed more accurately
- iter_on_empty_collectionsChecks for calls to iter, iter_mut or into_iter on empty collections
- iter_on_single_items`iter` call on a collection with only one item
- large_stack_framesChecks for functions that use a lot of stack space. This often happens when constructing a large type, such as an array with a lot of elements, or constructing many smaller-but-still-large structs, or copying around a lot of large types. This lint is a more general version of large_stack_arrays that is intended to look at functions as a whole instead of only individual array expressions inside of a function
- literal_string_with_formatting_argsthis looks like a formatting argument but it is not part of a formatting macro
- missing_const_for_fnthis could be a `const fn`
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
Up next
Related lintclippy::redundant_cloneChecks for a redundant clone() (and its relatives) which clones an owned value that is going to be dropped without further useRead it next →Did this answer your question?