Malformed suggestion for clippy::iter_kv_map when using vec! in map #16340
Description
Summary
Clippy gives malformed suggestion for fixing clippy::iter_kv_map, when vec! macro is used in the map.
Reproducer
Code:
use std::collections::HashMap;
pub fn main() {
let hm: HashMap<&str, &str> = HashMap::new();
let _ = hm.iter().map(|(key, _)| vec![key]);
}Issue occurs specifically when vec! is present. Using ie.:
hm.iter().map(|(key, _)| Vec::from([key]));doesn't trigger the problem.
Current output:
warning: iterating on a map's keys
--> src/main.rs:5:13
|
5 | let _ = hm.iter().map(|(key, _)| vec![key]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#iter_kv_map
= note: `#[warn(clippy::iter_kv_map)]` on by default
help: try
|
5 ~ let _ = hm.keys().map(|key| <[_]>::into_vec(
6 + // Using the intrinsic produces a dramatic improvement in stack usage for
7 + // unoptimized programs using this code path to construct large Vecs.
8 + $crate::boxed::box_new([$($x),+])
9 ~ ));
|
Desired output:
warning: iterating on a map's keys
--> src/main.rs:5:13
|
5 | let _ = hm.iter().map(|(key, _)| vec![key]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `hm.keys().map(|key| vec![key])`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#iter_kv_map
= note: `#[warn(clippy::iter_kv_map)]` on by default
Version
rustc 1.92.0 (ded5c06cf 2025-12-08)
binary: rustc
commit-hash: ded5c06cf21d2b93bffd5d884aa6e96934ee4234
commit-date: 2025-12-08
host: x86_64-unknown-linux-gnu
release: 1.92.0
LLVM version: 21.1.3
Additional Labels
No response