Inst map in transpile is always ignored with V2 backend

[nkanazawa1989]

Environment

• Qiskit Terra version: 0.23
• Python version: any
• Operating system: any

What is happening?

When we explicitly specify the inst_map argument in transpile, this must check the provided inst map and apply pulse gate if available. In #9343 support for target argument is added to the pulse gate pass. When both target and inst_map are provided for the pass, the inst map in the target overrides user provided inst_map value.

However, even if we don't explicitly specify the target, this parse function implicitly set the target option and the user specified inst map is always ignored with the V2 backend.
https://github.com/Qiskit/qiskit-terra/blob/a3b359b899d5d963272a7b424c8a283bc6bd4c0d/qiskit/compiler/transpiler.py#L999-L1003

How can we reproduce the issue?

from qiskit.providers.fake_provider import FakeHanoi, FakeHanoiV2
from qiskit.pulse import ScheduleBlock, InstructionScheduleMap
from qiskit import transpile, QuantumCircuit

inst_map = InstructionScheduleMap()
inst_map.add("x", (0,), schedule=ScheduleBlock(name="custom_x"))

qc = QuantumCircuit(1)
qc.x(0)

qc1 = transpile(qc, FakeHanoi(), inst_map=inst_map)
qc2 = transpile(qc, FakeHanoiV2(), inst_map=inst_map)

qc1 == qc2

This results in

False

Because

>>> qc1.calibrations
{'x': {((0,), ()): ScheduleBlock(, name="custom_x", transform=AlignLeft())}}

>>> qc2.calibrations
{}

What should happen?

Pulse gate should be applied to circuit with V2 backend.

Any suggestions?

No response

[wshanks]

Qiskit Terra version: 0.23

This threw me off at first because I only started seeing this when I tested against main rather than 0.23. I think #9343 introduced this issue which is not in 0.23.

Besides the code block you referenced that shows the target always getting pulled from the backend when not provided, the other part of the code that is problematic is blocks like this:

https://github.com/Qiskit/qiskit-terra/blob/e016f9ca612482fe2b15af4d54828cf3c1899f6f/qiskit/transpiler/passes/calibration/pulse_gate.py#L66-L68

which override the provided inst_map with the one from the target.