Fix bug where unexpected queuing occurs in qml.ctrl among other funct…

…ions (#6474)

This PR is a copy of this [other
one](#6284) pointing to
v0.39.0-rc0

[[sc-73690](https://app.shortcut.com/xanaduai/story/73690)]

---------

Co-authored-by: Astral Cai <[email protected]>

doc/releases/changelog-0.39.0.md

@@ -495,6 +495,9 @@
 * Fixes a bug where `default.tensor` raises an error when applying `Identity`/`GlobalPhase` on no wires, and `PauliRot`/`MultiRZ` on a single wire.
   [(#6448)](https://github.com/PennyLaneAI/pennylane/pull/6448)
 
+* Fixes a bug where applying `qml.ctrl` and `qml.adjoint` on an operator type instead of an operator instance results in extra operators in the queue.
+  [(#6284)](https://github.com/PennyLaneAI/pennylane/pull/6284)
+
 <h3>Contributors ✍️</h3>
 
 This release contains contributions from (in alphabetical order):

pennylane/ops/op_math/adjoint.py

@@ -236,6 +236,10 @@ def _adjoint_transform(qfunc: Callable, lazy=True) -> Callable:
     @wraps(qfunc)
     def wrapper(*args, **kwargs):
         qscript = make_qscript(qfunc)(*args, **kwargs)
+
+        leaves, _ = qml.pytrees.flatten((args, kwargs), lambda obj: isinstance(obj, Operator))
+        _ = [qml.QueuingManager.remove(l) for l in leaves if isinstance(l, Operator)]
+
         if lazy:
             adjoint_ops = [Adjoint(op) for op in reversed(qscript.operations)]
         else:

pennylane/ops/op_math/controlled.py

@@ -204,6 +204,9 @@ def _ctrl_transform(op, control, control_values, work_wires):
     def wrapper(*args, **kwargs):
         qscript = qml.tape.make_qscript(op)(*args, **kwargs)
 
+        leaves, _ = qml.pytrees.flatten((args, kwargs), lambda obj: isinstance(obj, Operator))
+        _ = [qml.QueuingManager.remove(l) for l in leaves if isinstance(l, Operator)]
+
         # flip control_values == 0 wires here, so we don't have to do it for each individual op.
         flip_control_on_zero = (len(qscript) > 1) and (control_values is not None)
         op_control_values = None if flip_control_on_zero else control_values

tests/ops/op_math/test_adjoint.py

@@ -884,6 +884,18 @@ def test_single_observable(self):
         qs = qml.tape.QuantumScript.from_queue(q)
         assert len(qs) == 0
 
+    def test_correct_queued_operators(self):
+        """Test that args and kwargs do not add operators to the queue."""
+
+        with qml.queuing.AnnotatedQueue() as q:
+            qml.adjoint(qml.QSVT)(qml.X(1), [qml.Z(1)])
+            qml.adjoint(qml.QSVT(qml.X(1), [qml.Z(1)]))
+
+        for op in q.queue:
+            assert op.name == "Adjoint(QSVT)"
+
+        assert len(q.queue) == 2
+
 
 class TestAdjointConstructorDifferentCallableTypes:
     """Test the adjoint transform on a variety of possible inputs."""

tests/ops/op_math/test_controlled.py

@@ -1872,6 +1872,17 @@ def test_nested_pauli_x_based_ctrl_ops(self):
         expected = qml.MultiControlledX(wires=[3, 2, 1, 0], control_values=[1, 0, 1])
         assert op == expected
 
+    def test_correct_queued_operators(self):
+        """Test that args and kwargs do not add operators to the queue."""
+
+        with qml.queuing.AnnotatedQueue() as q:
+            qml.ctrl(qml.QSVT, control=0)(qml.X(1), [qml.Z(1)])
+            qml.ctrl(qml.QSVT(qml.X(1), [qml.Z(1)]), control=0)
+        for op in q.queue:
+            assert op.name == "C(QSVT)"
+
+        assert len(q.queue) == 2
+
 
 class _Rot(Operation):
     """A rotation operation that is not an instance of Rot

tests/ops/op_math/test_prod.py

@@ -1425,6 +1425,18 @@ def test_nonlazy_mode_queueing(self):
         assert len(q) == 1
         assert q.queue[0] is prod2
 
+    def test_correct_queued_operators(self):
+        """Test that args and kwargs do not add operators to the queue."""
+
+        with qml.queuing.AnnotatedQueue() as q:
+            qml.prod(qml.QSVT)(qml.X(1), [qml.Z(1)])
+            qml.prod(qml.QSVT(qml.X(1), [qml.Z(1)]))
+
+        for op in q.queue:
+            assert op.name == "QSVT"
+
+        assert len(q.queue) == 2
+
 
 class TestIntegration:
     """Integration tests for the Prod class."""