Split must_use_unit test into an unfixable part

With the attribute refactor in rustc, making this case machine applicable is not
easily possible anymore. This splits up the tests properly.

tests/ui/must_use_unit.fixed

@@ -26,11 +26,3 @@ fn main() {
         fn foo() {}
     );
 }
-
-#[cfg_attr(all(), deprecated)]
-fn issue_12320() {}
-//~^ must_use_unit
-
-#[cfg_attr(all(), deprecated, doc = "foo")]
-fn issue_12320_2() {}
-//~^ must_use_unit

tests/ui/must_use_unit.rs

@@ -29,11 +29,3 @@ fn main() {
         fn foo() {}
     );
 }
-
-#[cfg_attr(all(), must_use, deprecated)]
-fn issue_12320() {}
-//~^ must_use_unit
-
-#[cfg_attr(all(), deprecated, doc = "foo", must_use)]
-fn issue_12320_2() {}
-//~^ must_use_unit

tests/ui/must_use_unit.stderr

@@ -25,21 +25,5 @@ LL | #[must_use = "With note"]
 LL | pub fn must_use_with_note() {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: this unit-returning function has a `#[must_use]` attribute
-  --> tests/ui/must_use_unit.rs:34:1
-   |
-LL | #[cfg_attr(all(), must_use, deprecated)]
-   |                   -------------------- help: change these attributes to: `deprecated`
-LL | fn issue_12320() {}
-   | ^^^^^^^^^^^^^^^^
-
-error: this unit-returning function has a `#[must_use]` attribute
-  --> tests/ui/must_use_unit.rs:38:1
-   |
-LL | #[cfg_attr(all(), deprecated, doc = "foo", must_use)]
-   |                   --------------------------------- help: change these attributes to: `deprecated, doc = "foo"`
-LL | fn issue_12320_2() {}
-   | ^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 

tests/ui/must_use_unit_12320.rs → tests/ui/must_use_unit_unfixable.rs

@@ -1,11 +1,11 @@
-//@aux-build:proc_macros.rs
 //@no-rustfix
 
-#![warn(clippy::must_use_unit)]
-#![allow(clippy::unused_unit)]
-
 #[cfg_attr(all(), must_use, deprecated)]
 fn issue_12320() {}
+//~^ must_use_unit
 
 #[cfg_attr(all(), deprecated, doc = "foo", must_use)]
 fn issue_12320_2() {}
+//~^ must_use_unit
+
+fn main() {}

tests/ui/must_use_unit_12320.stderr → tests/ui/must_use_unit_unfixable.stderr

@@ -1,25 +1,25 @@
 error: this unit-returning function has a `#[must_use]` attribute
-  --> tests/ui/must_use_unit_12320.rs:8:1
+  --> tests/ui/must_use_unit_unfixable.rs:4:1
    |
 LL | fn issue_12320() {}
    | ^^^^^^^^^^^^^^^^
    |
 help: remove `must_use`
-  --> tests/ui/must_use_unit_12320.rs:7:19
+  --> tests/ui/must_use_unit_unfixable.rs:3:19
    |
 LL | #[cfg_attr(all(), must_use, deprecated)]
    |                   ^^^^^^^^
-   = note: `-D clippy::double-must-use` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::double_must_use)]`
+   = 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_12320.rs:11:1
+  --> tests/ui/must_use_unit_unfixable.rs:8:1
    |
 LL | fn issue_12320_2() {}
    | ^^^^^^^^^^^^^^^^^^
    |
 help: remove `must_use`
-  --> tests/ui/must_use_unit_12320.rs:10:44
+  --> tests/ui/must_use_unit_unfixable.rs:7:44
    |
 LL | #[cfg_attr(all(), deprecated, doc = "foo", must_use)]
    |                                            ^^^^^^^^