error: use of `flat_map` with an identity function
  --> $DIR/flat_map_identity.rs:10:22
   |
LL |     let _ = iterator.flat_map(|x| x);
   |                      ^^^^^^^^^^^^^^^ help: try: `flatten()`
   |
   = note: `-D clippy::flat-map-identity` implied by `-D warnings`

error: use of `flat_map` with an identity function
  --> $DIR/flat_map_identity.rs:13:22
   |
LL |     let _ = iterator.flat_map(convert::identity);
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`

error: use of `flat_map` with an identity function
  --> $DIR/flat_map_identity.rs:16:22
   |
LL |     let _ = iterator.flat_map(|x| return x);
   |                      ^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`

error: aborting due to 3 previous errors