error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
  --> $DIR/double_must_use.rs:5:1
   |
LL | pub fn must_use_result() -> Result<(), ()> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: either add some descriptive text or remove the attribute
   = note: `-D clippy::double-must-use` implied by `-D warnings`

error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
  --> $DIR/double_must_use.rs:10:1
   |
LL | pub fn must_use_tuple() -> (Result<(), ()>, u8) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: either add some descriptive text or remove the attribute

error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
  --> $DIR/double_must_use.rs:15:1
   |
LL | pub fn must_use_array() -> [Result<(), ()>; 1] {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: either add some descriptive text or remove the attribute

error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
  --> $DIR/double_must_use.rs:31:1
   |
LL | async fn async_must_use_result() -> Result<(), ()> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: either add some descriptive text or remove the attribute

error: aborting due to 4 previous errors