Test const impl of cmp traits

Author: ecstatic-morse

library/core/tests/cmp.rs

@@ -203,3 +203,31 @@ fn cmp_default() {
     assert!(Fool(false) != Fool(false));
     assert_eq!(Fool(false), Fool(true));
 }
+
+struct S(i32);
+
+impl const PartialEq for S {
+    fn eq(&self, other: &Self) -> bool {
+        self.0 == other.0
+    }
+}
+
+impl const PartialOrd for S {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        let ret = match (self.0, other.0) {
+            (a, b) if a > b => Ordering::Greater,
+            (a, b) if a < b => Ordering::Less,
+            _ => Ordering::Equal,
+        };
+
+        Some(ret)
+    }
+}
+
+const _: () = assert!(S(1) == S(1));
+const _: () = assert!(S(0) != S(1));
+
+const _: () = assert!(S(1) <= S(1));
+const _: () = assert!(S(1) >= S(1));
+const _: () = assert!(S(0) <  S(1));
+const _: () = assert!(S(1) >  S(0));