Fix erroneous comment

Author: Nadrieril

src/test/ui/pattern/usefulness/match-empty-exhaustive_patterns.rs

@@ -23,7 +23,6 @@ fn foo(x: Foo) {
 }
 
 fn main() {
-    // `exhaustive_patterns` is not on, so uninhabited branches are not detected as unreachable.
     match None::<!> {
         None => {}
         Some(_) => {} //~ ERROR unreachable pattern

src/test/ui/pattern/usefulness/match-empty-exhaustive_patterns.stderr

@@ -11,51 +11,51 @@ LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error: unreachable pattern
-  --> $DIR/match-empty-exhaustive_patterns.rs:29:9
+  --> $DIR/match-empty-exhaustive_patterns.rs:28:9
    |
 LL |         Some(_) => {}
    |         ^^^^^^^
 
 error: unreachable pattern
-  --> $DIR/match-empty-exhaustive_patterns.rs:33:9
+  --> $DIR/match-empty-exhaustive_patterns.rs:32:9
    |
 LL |         Some(_) => {}
    |         ^^^^^^^
 
 error[E0004]: non-exhaustive patterns: type `u8` is non-empty
-  --> $DIR/match-empty-exhaustive_patterns.rs:36:11
+  --> $DIR/match-empty-exhaustive_patterns.rs:35:11
    |
 LL |     match 0u8 {}
    |           ^^^
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
 
 error[E0004]: non-exhaustive patterns: type `NonEmptyStruct` is non-empty
-  --> $DIR/match-empty-exhaustive_patterns.rs:38:11
+  --> $DIR/match-empty-exhaustive_patterns.rs:37:11
    |
 LL |     match NonEmptyStruct(true) {}
    |           ^^^^^^^^^^^^^^^^^^^^
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
 
 error[E0004]: non-exhaustive patterns: type `NonEmptyEnum1` is non-empty
-  --> $DIR/match-empty-exhaustive_patterns.rs:40:11
+  --> $DIR/match-empty-exhaustive_patterns.rs:39:11
    |
 LL |     match NonEmptyEnum1::Foo(true) {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
 
 error[E0004]: non-exhaustive patterns: type `NonEmptyEnum2` is non-empty
-  --> $DIR/match-empty-exhaustive_patterns.rs:42:11
+  --> $DIR/match-empty-exhaustive_patterns.rs:41:11
    |
 LL |     match NonEmptyEnum2::Foo(true) {}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
 
 error[E0004]: non-exhaustive patterns: type `NonEmptyEnum5` is non-empty
-  --> $DIR/match-empty-exhaustive_patterns.rs:44:11
+  --> $DIR/match-empty-exhaustive_patterns.rs:43:11
    |
 LL |     match NonEmptyEnum5::V1 {}
    |           ^^^^^^^^^^^^^^^^^