From a24386e534942265f69c8b62c9730ae7a11dae13 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Thu, 6 Feb 2025 16:36:16 -0500
Subject: [PATCH 01/11] initial commit

---
 pennylane/wires.py  | 2 ++
 tests/test_wires.py | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 14b5174679f..cea46e1a4a5 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,6 +93,7 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
+    tuple_of_wires = tuple(qml.pytrees.flatten(tuple(wires), is_leaf=lambda x: False)[0])
     return tuple_of_wires
 
 
@@ -155,6 +156,7 @@ def __len__(self):
     def contains_wires(self, wires):
         """Method to determine if Wires object contains wires in another Wires object."""
         if isinstance(wires, Wires):
+            wires = Wires(tuple(qml.pytrees.flatten(tuple(wires), is_leaf=lambda x: False)[0]))
             return set(wires.labels).issubset(set(self._labels))
         return False
 
diff --git a/tests/test_wires.py b/tests/test_wires.py
index 0ae3e85b65d..511da0d9655 100644
--- a/tests/test_wires.py
+++ b/tests/test_wires.py
@@ -74,7 +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 == (Wires([0]), Wires([1]), Wires([2]))
+        assert wires.labels == (0, 1, 2)
 
     @pytest.mark.parametrize(
         "iterable", [[1, 0, 4], ["a", "b", "c"], [0, 1, None], ["a", 1, "ancilla"]]
@@ -148,7 +148,7 @@ def test_contains(
         wires = Wires([0, 1, 2, 3, Wires([4, 5]), None])
 
         assert 0 in wires
-        assert Wires([4, 5]) in wires
+        assert Wires([4, 5]) not in wires
         assert None in wires
         assert Wires([1]) not in wires
         assert Wires([0, 3]) not in wires
@@ -170,7 +170,7 @@ def test_contains_wires(
 
         assert not wires.contains_wires(0)  # wrong type
         assert not wires.contains_wires([0, 1])  # wrong type
-        assert not wires.contains_wires(
+        assert wires.contains_wires(
             Wires([4, 5])
         )  # looks up 4 and 5 in wires, which are not present
 

From eae9fbc7ba42c3f7782221b7ea39e6768ed1cdd4 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 10:04:54 -0500
Subject: [PATCH 02/11] new attempt

---
 pennylane/wires.py | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index cea46e1a4a5..980deb01294 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,10 +93,17 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
-    tuple_of_wires = tuple(qml.pytrees.flatten(tuple(wires), is_leaf=lambda x: False)[0])
+    tuple_of_wires = tuple(itertools.chain(*(wire_map(x) for x in tuple_of_wires)))
     return tuple_of_wires
 
 
+def wire_map(wires):
+    """Converts the input to a tuple of wire labels."""
+    if isinstance(wires, Wires):
+        return wires.labels
+    return [wires]
+
+
 class Wires(Sequence):
     r"""
     A bookkeeping class for wires, which are ordered collections of unique objects.
@@ -121,7 +128,7 @@ class Wires(Sequence):
     """
 
     def _flatten(self):
-        """Serialize Wires into a flattened representation according to the PyTree convension."""
+        """Serialize Wires into a flattened representation according to the PyTree convention."""
         return self._labels, ()
 
     @classmethod
@@ -156,7 +163,6 @@ def __len__(self):
     def contains_wires(self, wires):
         """Method to determine if Wires object contains wires in another Wires object."""
         if isinstance(wires, Wires):
-            wires = Wires(tuple(qml.pytrees.flatten(tuple(wires), is_leaf=lambda x: False)[0]))
             return set(wires.labels).issubset(set(self._labels))
         return False
 

From e2097b4ae98d1a3776d8ed9d89c2d83352aab4b6 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 10:09:39 -0500
Subject: [PATCH 03/11] reformat

---
 pennylane/wires.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 980deb01294..31295cb4664 100644
--- a/pennylane/wires.py
+++ b/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}.")
 
-    tuple_of_wires = tuple(itertools.chain(*(wire_map(x) for x in tuple_of_wires)))
-    return tuple_of_wires
+    return tuple(itertools.chain(*(wire_map(x) for x in tuple_of_wires)))
 
 
 def wire_map(wires):

From f19e7dfa112ddfde8fd461384a5d234e3ac9b034 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 10:11:58 -0500
Subject: [PATCH 04/11] changelog

---
 doc/releases/changelog-dev.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/releases/changelog-dev.md b/doc/releases/changelog-dev.md
index ea1a8d5184c..cda9397e4b3 100644
--- a/doc/releases/changelog-dev.md
+++ b/doc/releases/changelog-dev.md
@@ -227,6 +227,9 @@
 
 <h3>Internal changes ⚙️</h3>
 
+* Fix `qml.wires.Wires` initialization to disallow `Wires` objects as wires labels.
+  [(#6933)](https://github.com/PennyLaneAI/pennylane/pull/6933)
+
 * Remove `QNode.get_gradient_fn` from source code.
   [(#6898)](https://github.com/PennyLaneAI/pennylane/pull/6898)
   

From 1353bb527252c05cfbb9bba0a70146bacd9ac12b Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 10:29:49 -0500
Subject: [PATCH 05/11] fixes

---
 pennylane/wires.py  | 10 +++++-----
 tests/test_wires.py |  5 +++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 31295cb4664..64c5207c715 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,14 +93,14 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
-    return tuple(itertools.chain(*(wire_map(x) for x in tuple_of_wires)))
+    return tuple(itertools.chain(*(flatten_wires_object(x) for x in tuple_of_wires)))
 
 
-def wire_map(wires):
+def flatten_wires_object(wire_label):
     """Converts the input to a tuple of wire labels."""
-    if isinstance(wires, Wires):
-        return wires.labels
-    return [wires]
+    if isinstance(wire_label, Wires):
+        return wire_label.labels
+    return [wire_label]
 
 
 class Wires(Sequence):
diff --git a/tests/test_wires.py b/tests/test_wires.py
index 511da0d9655..06b40fcdcd3 100644
--- a/tests/test_wires.py
+++ b/tests/test_wires.py
@@ -34,6 +34,11 @@
 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])])
+
     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."):

From 8140768cf4536f59da2ea1bbaa854103b6283a7e Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 10:48:55 -0500
Subject: [PATCH 06/11] try to fix sphinx

---
 pennylane/wires.py | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 64c5207c715..7c9e9a31110 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -96,13 +96,6 @@ def _process(wires):
     return tuple(itertools.chain(*(flatten_wires_object(x) for x in tuple_of_wires)))
 
 
-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]
-
-
 class Wires(Sequence):
     r"""
     A bookkeeping class for wires, which are ordered collections of unique objects.
@@ -738,5 +731,13 @@ 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

From c132369cf67022c237f03999383a164811730afd Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 11:13:45 -0500
Subject: [PATCH 07/11] try to fix sphinx

---
 pennylane/wires.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 7c9e9a31110..afa6e4572cf 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,7 +93,7 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
-    return tuple(itertools.chain(*(flatten_wires_object(x) for x in tuple_of_wires)))
+    return tuple(itertools.chain(*(_flatten_wires_object(x) for x in tuple_of_wires)))
 
 
 class Wires(Sequence):
@@ -732,7 +732,7 @@ def __rxor__(self, other):
 WiresLike = Union[Wires, Iterable[Hashable], Hashable]
 
 
-def flatten_wires_object(wire_label):
+def _flatten_wires_object(wire_label):
     """Converts the input to a tuple of wire labels."""
     if isinstance(wire_label, Wires):
         return wire_label.labels

From b8d6554cc7ca20bf1e29396f7fd6ff0d8f234a70 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 14:12:33 -0500
Subject: [PATCH 08/11] address code review

---
 doc/releases/changelog-dev.md | 1 +
 tests/test_wires.py           | 1 +
 2 files changed, 2 insertions(+)

diff --git a/doc/releases/changelog-dev.md b/doc/releases/changelog-dev.md
index cda9397e4b3..13017238bfa 100644
--- a/doc/releases/changelog-dev.md
+++ b/doc/releases/changelog-dev.md
@@ -228,6 +228,7 @@
 <h3>Internal changes ⚙️</h3>
 
 * Fix `qml.wires.Wires` initialization to disallow `Wires` objects as wires labels.
+  Now, `Wires` is idempotent, e.g. `Wires([Wires([0]), Wires([1])])==Wires([0, 1])`.
   [(#6933)](https://github.com/PennyLaneAI/pennylane/pull/6933)
 
 * Remove `QNode.get_gradient_fn` from source code.
diff --git a/tests/test_wires.py b/tests/test_wires.py
index 06b40fcdcd3..d80f5e5cd66 100644
--- a/tests/test_wires.py
+++ b/tests/test_wires.py
@@ -38,6 +38,7 @@ 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."""

From 5540ca47668b253214d579a44f85c25f36b8b7a4 Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Fri, 7 Feb 2025 16:14:30 -0500
Subject: [PATCH 09/11] changelog

---
 doc/releases/changelog-dev.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/doc/releases/changelog-dev.md b/doc/releases/changelog-dev.md
index 16fc0552626..2c41c4cee33 100644
--- a/doc/releases/changelog-dev.md
+++ b/doc/releases/changelog-dev.md
@@ -230,10 +230,6 @@
 
 <h3>Internal changes ⚙️</h3>
 
-* Fix `qml.wires.Wires` initialization to disallow `Wires` objects as wires labels.
-  Now, `Wires` is idempotent, e.g. `Wires([Wires([0]), Wires([1])])==Wires([0, 1])`.
-  [(#6933)](https://github.com/PennyLaneAI/pennylane/pull/6933)
-
 * Remove `QNode.get_gradient_fn` from source code.
   [(#6898)](https://github.com/PennyLaneAI/pennylane/pull/6898)
   
@@ -270,6 +266,10 @@
 
 <h3>Bug fixes 🐛</h3>
 
+* Fix `qml.wires.Wires` initialization to disallow `Wires` objects as wires labels.
+  Now, `Wires` is idempotent, e.g. `Wires([Wires([0]), Wires([1])])==Wires([0, 1])`.
+  [(#6933)](https://github.com/PennyLaneAI/pennylane/pull/6933)
+
 * `qml.capture.PlxprInterpreter` now correctly handles propagation of constants when interpreting higher-order primitives
   [(#6913)](https://github.com/PennyLaneAI/pennylane/pull/6913)
 

From 2da3cbfa309ee5da0d2d0e4e0f062ccc36855f2f Mon Sep 17 00:00:00 2001
From: andrijapau <andrija.paurevic@xanadu.ai>
Date: Mon, 10 Feb 2025 10:38:24 -0500
Subject: [PATCH 10/11] add comment with explanation

---
 pennylane/wires.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index afa6e4572cf..9b3f6e0a460 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,6 +93,9 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
+    # Tuple of wires are flattened by iterating through each wire label and
+    # checking if it is a Wires object. If so, flatten the Wires object into a tuple of wire labels.
+    # The nested tuple of wires are then stitched together using itertools.chain.
     return tuple(itertools.chain(*(_flatten_wires_object(x) for x in tuple_of_wires)))
 
 

From 446a27ac74baeb6ddd30be98b76d2d0ed2e3b4d2 Mon Sep 17 00:00:00 2001
From: Andrija Paurevic <46359773+andrijapau@users.noreply.github.com>
Date: Mon, 10 Feb 2025 11:22:10 -0500
Subject: [PATCH 11/11] Update pennylane/wires.py

---
 pennylane/wires.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/pennylane/wires.py b/pennylane/wires.py
index 9b3f6e0a460..ba1fc175a69 100644
--- a/pennylane/wires.py
+++ b/pennylane/wires.py
@@ -93,9 +93,7 @@ def _process(wires):
     if len(set_of_wires) != len(tuple_of_wires):
         raise WireError(f"Wires must be unique; got {wires}.")
 
-    # Tuple of wires are flattened by iterating through each wire label and
-    # checking if it is a Wires object. If so, flatten the Wires object into a tuple of wire labels.
-    # The nested tuple of wires are then stitched together using itertools.chain.
+    # required to make `Wires` object idempotent
     return tuple(itertools.chain(*(_flatten_wires_object(x) for x in tuple_of_wires)))