QuantumCircuit.copy(name=?) allows for any object to be used as name #10487
Description
Environment
- Qiskit Terra version: 0.43.1 meta package, terra 0.24.1
- Python version: 3.10
- Operating system: docker continuumio/miniconda3
What is happening?
Creating a circuit via copy allows to give an invalid name (not a string), that is then checked only when the circuit is transpiled.
In this case the copy() api raises no error when passing a circuit as name (see API: copy)
How can we reproduce the issue?
Run this python script:
from qiskit import QuantumCircuit
from qiskit.compiler import transpile
qc_output = QuantumCircuit(2, 2)
input_circuit = QuantumCircuit(2, 2)
input_circuit.measure([0, 1], [0, 1])
qc_output = qc_output.compose(input_circuit, qubits=range(2))
final_circuit = qc_output.copy(qc_output)
final_circuit.measure([0, 1], [0, 1])
print(final_circuit.draw())
print("Circuit name: ", final_circuit.name)
transpile(final_circuit, optimization_level=0)Produces this output and error:
┌─┐ ┌─┐
q_0: ┤M├───┤M├───
└╥┘┌─┐└╥┘┌─┐
q_1: ─╫─┤M├─╫─┤M├
║ └╥┘ ║ └╥┘
c: 2/═╩══╩══╩══╩═
0 1 0 1
Circuit name: ┌─┐
q_0: ┤M├───
└╥┘┌─┐
q_1: ─╫─┤M├
║ └╥┘
c: 2/═╩══╩═
0 1
Traceback (most recent call last):
File "myfile.py", line 13, in <module> transpile(final_circuit, optimization_level=0)
File ".../qiskit/compiler/transpiler.py", line 380, in transpile _serial_transpile_circuit(
File ".../qiskit/compiler/transpiler.py", line 462, in _serial_transpile_circuit result = pass_manager.run(circuit, callback=callback, output_name=outpu
t_name) File ".../qiskit/transpiler/passmanager.py", line 537, in run return super().run(circuits, output_name, callback)
File ".../qiskit/transpiler/passmanager.py", line 231, in run return self._run_single_circuit(circuits, output_name, callback)
File ".../qiskit/transpiler/passmanager.py", line 292, in _run_single_circuit result = running_passmanager.run(circuit, output_name=output_name, call
back=callback) File ".../qiskit/transpiler/runningpassmanager.py", line 127, in run circuit = dag_to_circuit(dag, copy_operations=False)
File ".../qiskit/converters/dag_to_circuit.py", line 58, in dag_to_circuit circuit = QuantumCircuit(
File ".../qiskit/circuit/quantumcircuit.py", line 260, in __init__ raise CircuitError(
qiskit.circuit.exceptions.CircuitError: 'The circuit name should be a strin
g (or None to auto-generate a name).'What should happen?
I would expect the copy method to check the name of the circuit, and raise an error if it is not a string, whereas now it is allowed without any check (see here).
Even this is allowed:
...
class AnyObject(object):
def __init__(self, field):
self.field = field
new_circuit = qc_output.copy(name=AnyObject("new_circuit"))
print(new_circuit.name)Outputting:
...
<__main__.AnyObject object at 0x7f7c98809ab0>
Any suggestions?
I think the copy method should check the name of the circuit, and raise an error if it is not a string, so that the error is more precise on the line of the copy() call rather than the transpile().