dynamic circuit fail to transpile without a backend

[1ucian0]

Environment

• Qiskit version: 1.1.0.dev0+afdd1b7
• Python version: 3.11.7
• Operating system: MacOS

What is happening?

When transpiling a dynamic circuit without any backend, it fails with The control-flow construct 'if_else' is not supported by the backend.
This seems to be the backendless version of Qiskit/qiskit-ibm-runtime#1253

How can we reproduce the issue?

from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, transpile

q = QuantumRegister(1)
c = ClassicalRegister(1)
circuit = QuantumCircuit(q, c)
circuit.h(q)
circuit.measure(q, c)
with circuit.if_test((c, 1)):
    circuit.x(q)

transpile(circuit)

TranspilerError: "The control-flow construct 'if_else' is not supported by the backend."

What should happen?

transpilation should work with dynamic circuits, just like the non-dynamic circuits:

from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister, transpile

q = QuantumRegister(1)
c = ClassicalRegister(1)
circuit = QuantumCircuit(q, c)
circuit.h(q)
circuit.measure(q, c)

transpiled = transpile(circuit)
transpiled.draw('mpl')

Any suggestions?

No response

[jakelishman]

Whoops, looks like an oversight in the control-flow error check. Something like #11907 should do the job.

[jakelishman]

Fwiw, the linked issue doesn't appear to be a problem with Terra (though could be related via #11877) - it seems like there are/were some backends in the IBM Runtime that weren't reporting their support for control-flow operations.

[1ucian0]

wow! that's a quick fix! Thanks!