1 files changed, 42 insertions, 0 deletions
diff --git a/src/test/ui/specialization/soundness/partial_ord_slice.rs b/src/test/ui/specialization/soundness/partial_ord_slice.rs
new file mode 100644
index 000000000..b9e80a48d
--- /dev/null
+++ b/src/test/ui/specialization/soundness/partial_ord_slice.rs
@@ -0,0 +1,42 @@
+// Check that we aren't using unsound specialization in slice comparisons.
+
+// run-pass
+
+use std::cell::Cell;
+use std::cmp::Ordering;
+
+struct Evil<'a, 'b>(Cell<(&'a [i32], &'b [i32])>);
+
+impl PartialEq for Evil<'_, '_> {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+
+impl Eq for Evil<'_, '_> {}
+
+impl PartialOrd for Evil<'_, '_> {
+    fn partial_cmp(&self, _other: &Self) -> Option<Ordering> {
+        Some(Ordering::Equal)
+    }
+}
+
+impl<'a> Ord for Evil<'a, 'a> {
+    fn cmp(&self, _other: &Self) -> Ordering {
+        let (a, b) = self.0.get();
+        self.0.set((b, a));
+        Ordering::Equal
+    }
+}
+
+fn main() {
+    let x = &[1, 2, 3, 4];
+    let u = {
+        let a = Box::new([7, 8, 9, 10]);
+        let y = [Evil(Cell::new((x, &*a)))];
+        let _ = &y[..] <= &y[..];
+        let [Evil(c)] = y;
+        c.get().0
+    };
+    assert_eq!(u, &[1, 2, 3, 4]);
+}