add must_use tests for Result<MustUse/Struct, !>

Author: WaffleLapkin

tests/ui/lint/unused/must_use-result-unit-uninhabited.rs

@@ -7,6 +7,11 @@
 use core::ops::{ControlFlow, ControlFlow::Continue};
 use dep::{MyUninhabited, MyUninhabitedNonexhaustive};
 
+#[must_use]
+struct MustUse;
+
+struct Struct;
+
 fn result_unit_unit() -> Result<(), ()> {
     Ok(())
 }
@@ -19,6 +24,14 @@ fn result_unit_never() -> Result<(), !> {
     Ok(())
 }
 
+fn result_struct_never() -> Result<Struct, !> {
+    Ok(Struct)
+}
+
+fn result_must_use_never() -> Result<MustUse, !> {
+    Ok(MustUse)
+}
+
 fn result_unit_myuninhabited() -> Result<(), MyUninhabited> {
     Ok(())
 }
@@ -80,6 +93,8 @@ fn main() {
     result_unit_unit(); //~ ERROR: unused `Result` that must be used
     result_unit_infallible();
     result_unit_never();
+    result_must_use_never(); //~ ERROR: unused `Result` that must be used
+    result_struct_never(); //~ ERROR: unused `Result` that must be used
     result_unit_myuninhabited();
     result_unit_myuninhabited_nonexhaustive(); //~ ERROR: unused `Result` that must be used
     result_unit_assoctype(S1);

tests/ui/lint/unused/must_use-result-unit-uninhabited.stderr

@@ -1,5 +1,5 @@
 error: unused `Result` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:80:5
+  --> $DIR/must_use-result-unit-uninhabited.rs:93:5
    |
 LL |     result_unit_unit();
    |     ^^^^^^^^^^^^^^^^^^
@@ -16,7 +16,31 @@ LL |     let _ = result_unit_unit();
    |     +++++++
 
 error: unused `Result` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:84:5
+  --> $DIR/must_use-result-unit-uninhabited.rs:96:5
+   |
+LL |     result_must_use_never();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this `Result` may be an `Err` variant, which should be handled
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |     let _ = result_must_use_never();
+   |     +++++++
+
+error: unused `Result` that must be used
+  --> $DIR/must_use-result-unit-uninhabited.rs:97:5
+   |
+LL |     result_struct_never();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this `Result` may be an `Err` variant, which should be handled
+help: use `let _ = ...` to ignore the resulting value
+   |
+LL |     let _ = result_struct_never();
+   |     +++++++
+
+error: unused `Result` that must be used
+  --> $DIR/must_use-result-unit-uninhabited.rs:99:5
    |
 LL |     result_unit_myuninhabited_nonexhaustive();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -28,7 +52,7 @@ LL |     let _ = result_unit_myuninhabited_nonexhaustive();
    |     +++++++
 
 error: unused `Result` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:86:5
+  --> $DIR/must_use-result-unit-uninhabited.rs:101:5
    |
 LL |     result_unit_assoctype(S2);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -40,7 +64,7 @@ LL |     let _ = result_unit_assoctype(S2);
    |     +++++++
 
 error: unused `Result` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:88:5
+  --> $DIR/must_use-result-unit-uninhabited.rs:103:5
    |
 LL |     S2.method_use_assoc_type();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -52,7 +76,7 @@ LL |     let _ = S2.method_use_assoc_type();
    |     +++++++
 
 error: unused `ControlFlow` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:90:5
+  --> $DIR/must_use-result-unit-uninhabited.rs:105:5
    |
 LL |     controlflow_unit();
    |     ^^^^^^^^^^^^^^^^^^
@@ -63,7 +87,7 @@ LL |     let _ = controlflow_unit();
    |     +++++++
 
 error: unused `Result` that must be used
-  --> $DIR/must_use-result-unit-uninhabited.rs:99:9
+  --> $DIR/must_use-result-unit-uninhabited.rs:114:9
    |
 LL |         self.generate();
    |         ^^^^^^^^^^^^^^^
@@ -74,5 +98,5 @@ help: use `let _ = ...` to ignore the resulting value
 LL |         let _ = self.generate();
    |         +++++++
 
-error: aborting due to 6 previous errors
+error: aborting due to 8 previous errors