1 files changed, 113 insertions, 0 deletions
diff --git a/src/test/ui/pattern/usefulness/integer-ranges/reachability.rs b/src/test/ui/pattern/usefulness/integer-ranges/reachability.rs
new file mode 100644
index 000000000..fb4d59b05
--- /dev/null
+++ b/src/test/ui/pattern/usefulness/integer-ranges/reachability.rs
@@ -0,0 +1,113 @@
+#![feature(exclusive_range_pattern)]
+#![allow(overlapping_range_endpoints)]
+#![deny(unreachable_patterns)]
+
+macro_rules! m {
+    ($s:expr, $t1:pat, $t2:pat) => {
+        match $s {
+            $t1 => {}
+            $t2 => {}
+            _ => {}
+        }
+    }
+}
+
+fn main() {
+    m!(0u8, 42, 41);
+    m!(0u8, 42, 42); //~ ERROR unreachable pattern
+    m!(0u8, 42, 43);
+
+    m!(0u8, 20..=30, 19);
+    m!(0u8, 20..=30, 20); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 21); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 25); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 29); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 30); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 31);
+    m!(0u8, 20..30, 19);
+    m!(0u8, 20..30, 20); //~ ERROR unreachable pattern
+    m!(0u8, 20..30, 21); //~ ERROR unreachable pattern
+    m!(0u8, 20..30, 25); //~ ERROR unreachable pattern
+    m!(0u8, 20..30, 29); //~ ERROR unreachable pattern
+    m!(0u8, 20..30, 30);
+    m!(0u8, 20..30, 31);
+
+    m!(0u8, 20..=30, 20..=30); //~ ERROR unreachable pattern
+    m!(0u8, 20.. 30, 20.. 30); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 20.. 30); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 19..=30);
+    m!(0u8, 20..=30, 21..=30); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 20..=29); //~ ERROR unreachable pattern
+    m!(0u8, 20..=30, 20..=31);
+    m!('a', 'A'..='z', 'a'..='z'); //~ ERROR unreachable pattern
+
+    match 0u8 {
+        5 => {},
+        6 => {},
+        7 => {},
+        8 => {},
+        5..=8 => {}, //~ ERROR unreachable pattern
+        _ => {},
+    }
+    match 0u8 {
+        0..10 => {},
+        10..20 => {},
+        5..15 => {}, //~ ERROR unreachable pattern
+        _ => {},
+    }
+    match 0u8 {
+        0..10 => {},
+        10..20 => {},
+        20..30 => {},
+        5..25 => {}, //~ ERROR unreachable pattern
+        _ => {},
+    }
+    match 0u8 {
+        0..10 => {},
+        10 => {},
+        11..=23 => {},
+        19..30 => {},
+        5..25 => {}, //~ ERROR unreachable pattern
+        _ => {},
+    }
+    match 0usize {
+        0..10 => {},
+        10..20 => {},
+        5..15 => {}, //~ ERROR unreachable pattern
+        _ => {},
+    }
+    // Chars between '\u{D7FF}' and '\u{E000}' are invalid even though ranges that contain them are
+    // allowed.
+    match 'a' {
+        _ => {},
+        '\u{D7FF}'..='\u{E000}' => {}, //~ ERROR unreachable pattern
+    }
+    match 'a' {
+        '\u{0}'..='\u{D7FF}' => {},
+        '\u{E000}'..='\u{10_FFFF}' => {},
+        '\u{D7FF}'..='\u{E000}' => {}, // FIXME should be unreachable
+    }
+
+    match (0u8, true) {
+        (0..=255, false) => {}
+        (0..=255, true) => {} // ok
+    }
+    match (true, 0u8) {
+        (false, 0..=255) => {}
+        (true, 0..=255) => {} // ok
+    }
+
+    const FOO: i32 = 42;
+    const BAR: &i32 = &42;
+    match &0 {
+        &42 => {}
+        &FOO => {} //~ ERROR unreachable pattern
+        BAR => {} //~ ERROR unreachable pattern
+        _ => {}
+    }
+    // Regression test, see https://github.com/rust-lang/rust/pull/66326#issuecomment-552889933
+    match &0 {
+        BAR => {} // ok
+        _ => {}
+    }
+}