error: unnecessary use of `first().is_some()` to check if slice is not empty
  --> tests/ui/unnecessary_first_then_check.rs:6:19
   |
LL |     let _: bool = s.first().is_some();
   |                   ^^^^^^^^^^^^^^^^^^^ help: replace this with: `!s.is_empty()`
   |
   = note: `-D clippy::unnecessary-first-then-check` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::unnecessary_first_then_check)]`

error: unnecessary use of `first().is_none()` to check if slice is empty
  --> tests/ui/unnecessary_first_then_check.rs:7:21
   |
LL |     let _: bool = s.first().is_none();
   |                     ^^^^^^^^^^^^^^^^^ help: replace this with: `is_empty()`

error: unnecessary use of `first().is_some()` to check if slice is not empty
  --> tests/ui/unnecessary_first_then_check.rs:10:19
   |
LL |     let _: bool = v.first().is_some();
   |                   ^^^^^^^^^^^^^^^^^^^ help: replace this with: `!v.is_empty()`

error: unnecessary use of `first().is_some()` to check if slice is not empty
  --> tests/ui/unnecessary_first_then_check.rs:13:19
   |
LL |     let _: bool = n[0].first().is_some();
   |                   ^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `!n[0].is_empty()`

error: unnecessary use of `first().is_none()` to check if slice is empty
  --> tests/ui/unnecessary_first_then_check.rs:14:24
   |
LL |     let _: bool = n[0].first().is_none();
   |                        ^^^^^^^^^^^^^^^^^ help: replace this with: `is_empty()`

error: unnecessary use of `first().is_some()` to check if slice is not empty
  --> tests/ui/unnecessary_first_then_check.rs:20:19
   |
LL |     let _: bool = f[0].bar.first().is_some();
   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `!f[0].bar.is_empty()`

error: unnecessary use of `first().is_none()` to check if slice is empty
  --> tests/ui/unnecessary_first_then_check.rs:21:28
   |
LL |     let _: bool = f[0].bar.first().is_none();
   |                            ^^^^^^^^^^^^^^^^^ help: replace this with: `is_empty()`

error: aborting due to 7 previous errors