The explicit_counter_loop lint is incorrectly triggered in this case:

let vec = vec![1,2,3]; let mut index = 0; for _v in &vec { index += 1 } run(|| { println!("index: {}", index); })

This is incorrect because the counter is used after the loop. Note that if the counter were used directly and not in a closure, the lint would not get triggered.

Rust playground: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=3f1f1216aa7a4344d6891fc9e4ccdd5c

> cargo clippy -V clippy 0.0.212 (3aea860 2019-09-03)