Fix passing duplicate by-reference arguments (#7306)

python/ray/tests/test_basic.py

@@ -1731,6 +1731,35 @@ def test_wait(ray_start_regular):
         ray.wait([1])
 
 
+def test_duplicate_args(ray_start_regular):
+    @ray.remote
+    def f(arg1,
+          arg2,
+          arg1_duplicate,
+          kwarg1=None,
+          kwarg2=None,
+          kwarg1_duplicate=None):
+        assert arg1 == kwarg1
+        assert arg1 != arg2
+        assert arg1 == arg1_duplicate
+        assert kwarg1 != kwarg2
+        assert kwarg1 == kwarg1_duplicate
+
+    # Test by-value arguments.
+    arg1 = [1]
+    arg2 = [2]
+    ray.get(
+        f.remote(
+            arg1, arg2, arg1, kwarg1=arg1, kwarg2=arg2, kwarg1_duplicate=arg1))
+
+    # Test by-reference arguments.
+    arg1 = ray.put([1])
+    arg2 = ray.put([2])
+    ray.get(
+        f.remote(
+            arg1, arg2, arg1, kwarg1=arg1, kwarg2=arg2, kwarg1_duplicate=arg1))
+
+
 if __name__ == "__main__":
     import pytest
     sys.exit(pytest.main(["-v", __file__]))