error: avoid using `collect()` when not needed
  --> $DIR/needless_collect.rs:11:29
   |
LL |     let len = sample.iter().collect::<Vec<_>>().len();
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `count()`
   |
   = note: `-D clippy::needless-collect` implied by `-D warnings`

error: avoid using `collect()` when not needed
  --> $DIR/needless_collect.rs:12:22
   |
LL |     if sample.iter().collect::<Vec<_>>().is_empty() {
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `next().is_none()`

error: avoid using `collect()` when not needed
  --> $DIR/needless_collect.rs:15:28
   |
LL |     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:16:35
   |
LL |     sample.iter().map(|x| (x, x)).collect::<HashMap<_, _>>().len();
   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `count()`

error: aborting due to 4 previous errors