Fix: Make use of copy_operations

- Use `copy_operations` to copy all of the operations obtained from `CircuitData` by calling deepcopy.
- Initialize `._data` manually for instances of `BlueprintCircuit` by calling `._build()`.
- Other small fixes.

crates/circuit/src/converters.rs

@@ -24,7 +24,7 @@ use crate::{circuit_data::CircuitData, dag_circuit::DAGCircuit};
 /// it contains callbacks to Python and should not be stored anywhere.
 #[derive(Debug)]
 pub(crate) struct QuantumCircuitData<'py> {
-    pub data: PyRef<'py, CircuitData>,
+    pub data: CircuitData,
     pub name: Option<Bound<'py, PyAny>>,
     pub calibrations: HashMap<String, Py<PyDict>>,
     pub metadata: Option<Bound<'py, PyAny>>,
@@ -38,7 +38,7 @@ pub(crate) struct QuantumCircuitData<'py> {
 impl<'py> FromPyObject<'py> for QuantumCircuitData<'py> {
     fn extract_bound(ob: &Bound<'py, PyAny>) -> PyResult<Self> {
         let circuit_data = ob.getattr("_data")?;
-        let data_borrowed = circuit_data.downcast::<CircuitData>()?.borrow();
+        let data_borrowed = circuit_data.extract::<CircuitData>()?;
         Ok(QuantumCircuitData {
             data: data_borrowed,
             name: ob.getattr("name").ok(),
@@ -53,14 +53,21 @@ impl<'py> FromPyObject<'py> for QuantumCircuitData<'py> {
     }
 }
 
-#[pyfunction]
+#[pyfunction(signature = (quantum_circuit, copy_operations = true, qubit_order = None, clbit_order = None))]
 fn circuit_to_dag(
     py: Python,
     quantum_circuit: QuantumCircuitData,
+    copy_operations: bool,
     qubit_order: Option<Vec<PyObject>>,
     clbit_order: Option<Vec<PyObject>>,
 ) -> PyResult<DAGCircuit> {
-    DAGCircuit::from_quantum_circuit(py, quantum_circuit, qubit_order, clbit_order)
+    DAGCircuit::from_quantum_circuit(
+        py,
+        quantum_circuit,
+        copy_operations,
+        qubit_order,
+        clbit_order,
+    )
 }
 
 pub fn converters(m: &Bound<PyModule>) -> PyResult<()> {

crates/circuit/src/dag_circuit.rs

@@ -6363,11 +6363,16 @@ impl DAGCircuit {
     pub(crate) fn from_quantum_circuit(
         py: Python,
         qc: QuantumCircuitData,
+        copy_op: bool,
         qubit_order: Option<Vec<PyObject>>,
         clbit_order: Option<Vec<PyObject>>,
     ) -> PyResult<DAGCircuit> {
         // Extract necessary attributes
-        let qc_data = qc.data;
+        let qc_data = if copy_op {
+            qc.data.copy(py, true, true)?
+        } else {
+            qc.data
+        };
         let num_qubits = qc_data.num_qubits();
         let num_clbits = qc_data.num_clbits();
         let num_ops = qc_data.__len__();
@@ -6420,10 +6425,9 @@ impl DAGCircuit {
             qubits
         } else {
             let qubits: Vec<Qubit> = (0..num_qubits as u32).map(Qubit).collect();
-            for qubit in &qubits {
-                let qubit = qc_data.qubits().get(*qubit).unwrap();
-                let bound = qubit.bind(py);
-                qubit_data.add(py, bound, false)?;
+            for qubit in qc_data.qubits().bits() {
+                let bound = qubit.clone_ref(py).into_bound(py);
+                qubit_data.add(py, &bound, false)?;
             }
             qubits
         };
@@ -6445,11 +6449,10 @@ impl DAGCircuit {
             }
             clbits
         } else {
-            let clbits: Vec<Clbit> = (0..num_clbits as u32).map(Clbit).collect();
-            for clbit in &clbits {
-                let clbit = qc_data.clbits().get(*clbit).unwrap();
-                let bound = clbit.bind(py);
-                clbit_data.add(py, bound, false)?;
+            let clbits: Vec<Clbit> = (0..num_qubits as u32).map(Clbit).collect();
+            for clbit in qc_data.clbits().bits() {
+                let bound = clbit.clone_ref(py).into_bound(py);
+                clbit_data.add(py, &bound, false)?;
             }
             clbits
         };
@@ -6507,8 +6510,6 @@ impl DAGCircuit {
         new_dag.calibrations = qc.calibrations;
         new_dag.metadata = qc.metadata.map(|meta| meta.unbind());
 
-        // TODO: Use Qubit ordering to remap the interners and qubit
-
         // Copy over all interners and registers
         new_dag.qargs_cache = qubit_interner;
         new_dag.cargs_cache = clbit_interner;

qiskit/converters/circuit_to_dag.py

@@ -12,8 +12,7 @@
 
 """Helper function for converting a circuit to a dag"""
 
-from qiskit.dagcircuit.dagcircuit import DAGCircuit
-from qiskit.dagcircuit.dagnode import DAGOpNode
+from qiskit.circuit.library.blueprintcircuit import BlueprintCircuit
 from qiskit._accelerate.circuit.converters import circuit_to_dag as core_circuit_to_dag
 
 
@@ -57,21 +56,22 @@ def circuit_to_dag(circuit, copy_operations=True, *, qubit_order=None, clbit_ord
             circ.rz(0.5, q[1]).c_if(c, 2)
             dag = circuit_to_dag(circ)
     """
-    if qubit_order is None:
-        qubits = circuit.qubits
-    elif len(qubit_order) != circuit.num_qubits or set(qubit_order) != set(circuit.qubits):
+    # If we have an instance of BluePrintCircuit, make sure it is built by calling ._build()
+    if isinstance(circuit, BlueprintCircuit):
+        if not circuit._is_built:
+            circuit._build()
+
+    if qubit_order is not None and (
+        len(qubit_order) != circuit.num_qubits or set(qubit_order) != set(circuit.qubits)
+    ):
         raise ValueError("'qubit_order' does not contain exactly the same qubits as the circuit")
-    else:
-        qubits = qubit_order
 
-    if clbit_order is None:
-        clbits = circuit.clbits
-    elif len(clbit_order) != circuit.num_clbits or set(clbit_order) != set(circuit.clbits):
+    if clbit_order is not None and (
+        len(clbit_order) != circuit.num_clbits or set(clbit_order) != set(circuit.clbits)
+    ):
         raise ValueError("'clbit_order' does not contain exactly the same clbits as the circuit")
-    else:
-        clbits = clbit_order
 
-    dagcircuit = core_circuit_to_dag(circuit, qubit_order, clbit_order)
+    dagcircuit = core_circuit_to_dag(circuit, copy_operations, qubit_order, clbit_order)
 
     dagcircuit.duration = circuit.duration
     dagcircuit.unit = circuit.unit