The unused parameter dag in DAGNode constructor is deprecated

qiskit/dagcircuit/dagnode.py

@@ -16,6 +16,7 @@
 
 import typing
 import uuid
+import warnings
 
 import qiskit._accelerate.circuit
 from qiskit.circuit import (
@@ -34,10 +35,25 @@
     from qiskit.dagcircuit import DAGCircuit
 
 
-DAGNode = qiskit._accelerate.circuit.DAGNode
-DAGOpNode = qiskit._accelerate.circuit.DAGOpNode
-DAGInNode = qiskit._accelerate.circuit.DAGInNode
-DAGOutNode = qiskit._accelerate.circuit.DAGOutNode
+def __init__wrapper__(func):
+    def wrapper(*args, **kwargs):
+        if "dag" in kwargs:
+            warnings.warn(
+                f"The 'dag' parameter in {func.__module__}.{func.__qualname__} "
+                "constructor is unused and it will be removed in Qiskit 2.0.",
+                category=DeprecationWarning,
+                stacklevel=2,
+            )
+        res = func(*args, **kwargs)
+        return res
+
+    return wrapper
+
+
+DAGNode = __init__wrapper__(qiskit._accelerate.circuit.DAGNode)
+DAGOpNode = __init__wrapper__(qiskit._accelerate.circuit.DAGOpNode)
+DAGInNode = __init__wrapper__(qiskit._accelerate.circuit.DAGInNode)
+DAGOutNode = __init__wrapper__(qiskit._accelerate.circuit.DAGOutNode)
 
 
 def _legacy_condition_eq(cond1, cond2, bit_indices1, bit_indices2) -> bool:

releasenotes/notes/deprecation_13022-9cf84f6c5ff13b29.yaml

@@ -0,0 +1,4 @@
+---
+deprecations_circuits:
+  - |
+    The ``DAGNode`` subclasses take a ``dag`` optional parameter when constructed that is currently unused and ignored. Now it is deprecated and will be removed in Qiskit 2.0