Add test

Author: Nadrieril

src/test/ui/or-patterns/exhaustiveness-unreachable-pattern.rs

@@ -77,10 +77,17 @@ fn main() {
         (false | true, false | true) => {}
     }
     match (true, true) {
-        (true, false) => {}
-        (false, true) => {}
+        (true, true) => {}
+        (false, false) => {}
         (false | true, false | true) => {}
     }
+    // https://github.com/rust-lang/rust/issues/76836
+    match None {
+        Some(false) => {}
+        None | Some(true
+                | false) => {} // expected unreachable warning here
+    }
+
     // A subpattern that is unreachable in all branches is overall unreachable.
     match (true, true) {
         (false, true) => {}

src/test/ui/or-patterns/exhaustiveness-unreachable-pattern.stderr

@@ -101,13 +101,13 @@ LL |         Some(0
    |              ^
 
 error: unreachable pattern
-  --> $DIR/exhaustiveness-unreachable-pattern.rs:89:15
+  --> $DIR/exhaustiveness-unreachable-pattern.rs:96:15
    |
 LL |             | true) => {}
    |               ^^^^
 
 error: unreachable pattern
-  --> $DIR/exhaustiveness-unreachable-pattern.rs:95:15
+  --> $DIR/exhaustiveness-unreachable-pattern.rs:102:15
    |
 LL |             | true,
    |               ^^^^