error: this unit-returning function has a `#[must_use]` attribute
  --> tests/ui/must_use_unit_unfixable.rs:4:1
   |
LL | fn issue_12320() {}
   | ^^^^^^^^^^^^^^^^
   |
help: remove `must_use`
  --> tests/ui/must_use_unit_unfixable.rs:3:19
   |
LL | #[cfg_attr(all(), must_use, deprecated)]
   |                   ^^^^^^^^
   = note: `-D clippy::must-use-unit` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(clippy::must_use_unit)]`

error: this unit-returning function has a `#[must_use]` attribute
  --> tests/ui/must_use_unit_unfixable.rs:8:1
   |
LL | fn issue_12320_2() {}
   | ^^^^^^^^^^^^^^^^^^
   |
help: remove `must_use`
  --> tests/ui/must_use_unit_unfixable.rs:7:44
   |
LL | #[cfg_attr(all(), deprecated, doc = "foo", must_use)]
   |                                            ^^^^^^^^

error: aborting due to 2 previous errors