CircuitInstruction qarg type changed without communication

[nkanazawa1989]

Environment

• Qiskit version: main
• Python version:
• Operating system:

What is happening?

CircuitInstruction qarg type is suddenly changed.

This can cause problem in unittest if one is testing instruction qubits without typecast.

How can we reproduce the issue?

See above screenshot

What should happen?

Data type must be preserved, or change must be mentioned in the release note

Any suggestions?

No response

[jakelishman]

Can you test data[0].qubits? Hopefully the type of that is still tuple. Even so, we should fix this.

Fwiw, treated CircuitInstruction as a 3-tuple with list elements (rather than using the attribute accessors) is a legacy backwards-compatible behaviour that comes with a runtime penalty. It was added during the switch of the type of the circuit data 2 years ago. We probably should have deprecated and removed it for 1.0, but forgot.

Either way, the type shouldn't have changed while it is supported,band we can get that fixed.