error: avoid using `collect()` when not needed
 --> $DIR/needless_collect.rs:7:28
  |
7 |     let len = sample.iter().collect::<Vec<_>>().len();
  |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `.count()`
  |
  = note: `-D needless-collect` implied by `-D warnings`

error: avoid using `collect()` when not needed
 --> $DIR/needless_collect.rs:8:21
  |
8 |     if sample.iter().collect::<Vec<_>>().is_empty() {
  |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `.next().is_none()`

error: avoid using `collect()` when not needed
  --> $DIR/needless_collect.rs:11:27
   |
11 |     sample.iter().cloned().collect::<Vec<_>>().contains(&1);
   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `.any(|&x| x == 1)`

error: avoid using `collect()` when not needed
  --> $DIR/needless_collect.rs:12:34
   |
12 |     sample.iter().map(|x| (x, x)).collect::<HashMap<_, _>>().len();
   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `.count()`

error: aborting due to 4 previous errors