clippy::string_extend_chars: calling `.extend(_.chars())`

What you see

warning: calling `.extend(_.chars())`
 --> main.rs:6:1
  |
6 | s.extend(abc.chars());
  | ^^^^^^^^^^^^^^^^^^^^^ help: try: `s.push_str(abc)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#string_extend_chars
  = note: `#[warn(clippy::string_extend_chars)]` on by default

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

.push_str(s) is clearer

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

let abc = "abc";
let def = String::from("def");
let mut s = String::new();
s.extend(abc.chars());
s.extend(def.chars());

Write this instead

let abc = "abc";
let def = String::from("def");
let mut s = String::new();
s.push_str(abc);
s.push_str(&def);

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

#[allow(clippy::string_extend_chars)]
fn my_function() { /* ... */ }

[lints.clippy]
string_extend_chars = "allow"

cargo clippy -- -A clippy::string-extend-chars

The [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.