False positive explicit_counter_loop when the counter is used in a closure after the loop

[madadam]

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)

[flip1995]

This should be fixable by changing this line:

rust-clippy/clippy_lints/src/loops.rs

Line 2190 in 087e5ea

NestedVisitorMap::None

to NestedVisitorMap::OnlyBodies(&self.cx.tcx.hir())