2 This lint warns about the use of literals as `print!`/`println!` args.
5 Using literals as `println!` args is inefficient
6 (c.f., https://github.com/matthiaskrgr/rust-str-bench) and unnecessary
7 (i.e., just put the literal in the format string)
11 println!("{}", "foo");
13 use the literal without formatting: