Revert "Fixes Wires objects as wire labels bug (#6933)"

This reverts commit e0b2174.

Author: mlxd

pennylane/wires.py

@@ -93,8 +93,7 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
-    # required to make `Wires` object idempotent
-    return tuple(itertools.chain(*(_flatten_wires_object(x) for x in tuple_of_wires)))
+    return tuple_of_wires
 
 
 class Wires(Sequence):
@@ -121,7 +120,7 @@ class Wires(Sequence):
     """
 
     def _flatten(self):
-        """Serialize Wires into a flattened representation according to the PyTree convention."""
+        """Serialize Wires into a flattened representation according to the PyTree convension."""
         return self._labels, ()
 
     @classmethod
@@ -732,13 +731,5 @@ def __rxor__(self, other):
 
 WiresLike = Union[Wires, Iterable[Hashable], Hashable]
 
-
-def _flatten_wires_object(wire_label):
-    """Converts the input to a tuple of wire labels."""
-    if isinstance(wire_label, Wires):
-        return wire_label.labels
-    return [wire_label]
-
-
 # Register Wires as a PyTree-serializable class
 register_pytree(Wires, Wires._flatten, Wires._unflatten)  # pylint: disable=protected-access

tests/test_wires.py

@@ -34,12 +34,6 @@
 class TestWires:
     """Tests for the ``Wires`` class."""
 
-    def test_wires_object_as_label(self):
-        """Tests that a Wires object can be used as a label for another Wires object."""
-        assert Wires([0, 1]) == Wires([Wires([0]), Wires([1])])
-        assert Wires(["a", "b", 1]) == Wires([Wires(["a", "b"]), Wires([1])])
-        assert Wires([Wires([(0, 0), (0, 1)])]) == Wires([(0, 0), (0, 1)])
-
     def test_error_if_wires_none(self):
         """Tests that a TypeError is raised if None is given as wires."""
         with pytest.raises(TypeError, match="Must specify a set of wires."):
@@ -80,7 +74,7 @@ def test_creation_from_wires_lists(self):
         """Tests that a Wires object can be created from a list of Wires."""
 
         wires = Wires([Wires([0]), Wires([1]), Wires([2])])
-        assert wires.labels == (0, 1, 2)
+        assert wires.labels == (Wires([0]), Wires([1]), Wires([2]))
 
     @pytest.mark.parametrize(
         "iterable", [[1, 0, 4], ["a", "b", "c"], [0, 1, None], ["a", 1, "ancilla"]]
@@ -154,7 +148,7 @@ def test_contains(
         wires = Wires([0, 1, 2, 3, Wires([4, 5]), None])
 
         assert 0 in wires
-        assert Wires([4, 5]) not in wires
+        assert Wires([4, 5]) in wires
         assert None in wires
         assert Wires([1]) not in wires
         assert Wires([0, 3]) not in wires
@@ -176,7 +170,7 @@ def test_contains_wires(
 
         assert not wires.contains_wires(0)  # wrong type
         assert not wires.contains_wires([0, 1])  # wrong type
-        assert wires.contains_wires(
+        assert not wires.contains_wires(
             Wires([4, 5])
         )  # looks up 4 and 5 in wires, which are not present