1 files changed, 152 insertions, 0 deletions
diff --git a/tests/ui/or-patterns/exhaustiveness-unreachable-pattern.rs b/tests/ui/or-patterns/exhaustiveness-unreachable-pattern.rs
new file mode 100644
index 00000000000..8429799cabf
--- /dev/null
+++ b/tests/ui/or-patterns/exhaustiveness-unreachable-pattern.rs
@@ -0,0 +1,152 @@
+#![deny(unreachable_patterns)]
+
+// We wrap patterns in a tuple because top-level or-patterns were special-cased.
+fn main() {
+    match (0u8,) {
+        (1 | 2,) => {}
+        (1,) => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+    match (0u8,) {
+        (1 | 2,) => {}
+        (2,) => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+    match (0u8,) {
+        (1,) => {}
+        (2,) => {}
+        (1 | 2,) => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+    match (0u8, 0u8) {
+        (1 | 2, 3 | 4) => {}
+        (1, 3) => {}     //~ ERROR unreachable pattern
+        (1, 4) => {}     //~ ERROR unreachable pattern
+        (2, 4) => {}     //~ ERROR unreachable pattern
+        (2 | 1, 4) => {} //~ ERROR unreachable pattern
+        (1, 5 | 6) => {}
+        (1, 4 | 5) => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+    match (true, true) {
+        (false | true, false | true) => (),
+    }
+    match (Some(0u8),) {
+        (None | Some(1 | 2),) => {}
+        (Some(1),) => {} //~ ERROR unreachable pattern
+        (None,) => {}    //~ ERROR unreachable pattern
+        _ => {}
+    }
+    match ((0u8,),) {
+        ((1 | 2,) | (3 | 4,),) => {}
+        ((1..=4,),) => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+
+    match (0,) {
+        (1 | 1,) => {} //~ ERROR unreachable
+        _ => {}
+    }
+    match 0 {
+        (0 | 1) | 1 => {} //~ ERROR unreachable
+        _ => {}
+    }
+    match 0 {
+        // We get two errors because recursive or-pattern expansion means we don't notice the two
+        // errors span a whole pattern. This could be better but doesn't matter much
+        0 | (0 | 0) => {}
+        //~^ ERROR unreachable
+        //~| ERROR unreachable
+        _ => {}
+    }
+    match None {
+        // There is only one error that correctly points to the whole subpattern
+        Some(0) |
+            Some( //~ ERROR unreachable
+                0 | 0) => {}
+        _ => {}
+    }
+    match [0; 2] {
+        [0
+            | 0 //~ ERROR unreachable
+        , 0
+            | 0] => {} //~ ERROR unreachable
+        _ => {}
+    }
+    match &[][..] {
+        [0] => {}
+        [0, _] => {}
+        [0, _, _] => {}
+        [1, ..] => {}
+        [1 //~ ERROR unreachable
+            | 2, ..] => {}
+        _ => {}
+    }
+    match &[][..] {
+        [true] => {}
+        [true | false, ..] => {}
+        _ => {}
+    }
+    match &[][..] {
+        [false] => {}
+        [true, ..] => {}
+        [true //~ ERROR unreachable
+            | false, ..] => {}
+        _ => {}
+    }
+    match (true, None) {
+        (true, Some(_)) => {}
+        (false, Some(true)) => {}
+        (true | false, None | Some(true //~ ERROR unreachable
+                                   | false)) => {}
+    }
+    macro_rules! t_or_f {
+        () => {
+            (true //~ ERROR unreachable
+            | false)
+        };
+    }
+    match (true, None) {
+        (true, Some(_)) => {}
+        (false, Some(true)) => {}
+        (true | false, None | Some(t_or_f!())) => {}
+    }
+    match Some(0) {
+        Some(0) => {}
+        Some(0 //~ ERROR unreachable
+             | 1) => {}
+        _ => {}
+    }
+
+    // A subpattern that is only unreachable in one branch is overall reachable.
+    match (true, true) {
+        (true, true) => {}
+        (false | true, false | true) => {}
+    }
+    match (true, 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) => {} //~ ERROR unreachable
+    }
+
+    // A subpattern that is unreachable in all branches is overall unreachable.
+    match (true, true) {
+        (false, true) => {}
+        (true, true) => {}
+        (false | true, false
+            | true) => {} //~ ERROR unreachable
+    }
+    match (true, true) {
+        (true, false) => {}
+        (true, true) => {}
+        (false
+            | true, //~ ERROR unreachable
+            false | true) => {}
+    }
+}