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Fix EngineProgram.get_circuit(_async) empty code detection #7850

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maffoo merged 2 commits into from
Jan 22, 2026
Merged

Fix EngineProgram.get_circuit(_async) empty code detection #7850

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b68f25f
Fix EngineProgram.get_circuit(_async) empty code detection
maffoo Jan 22, 2026
f5a2752
Add test cases with program that has no code
maffoo Jan 22, 2026
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4 changes: 3 additions & 1 deletion cirq-google/cirq_google/engine/engine_program.py
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Original file line number Diff line number Diff line change
Expand Up @@ -361,7 +361,9 @@ async def get_circuit_async(self) -> cirq.Circuit:
Returns:
The program's cirq Circuit.
"""
if self._program is None or self._program.code is None:
# The code field is an any_pb2.Any and is always set. But if the program has not
# been fetched this field may be empty, which we can see by checking the type_url.
if self._program is None or not self._program.code or not self._program.code.type_url:
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@pavoljuhas pavoljuhas Jan 22, 2026

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Should it be at the second alternative or not self._program.code.value?

The bool(any_pb2.Any()) is True so the middle expression is effectively or False or ...

Also can we add a test that would cover the fixed failure?

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@maffoo maffoo Jan 22, 2026

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This is mostly defense in depth because I didn't want to rely on the code attribute being set. As for whether we check type_url or value I think either is probably ok. I don't know if valid proto messages can ever have an empty byte representation, but I presume not? Do you have a particular reason to prefer value over type_url?

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@pavoljuhas pavoljuhas Jan 22, 2026 •
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If we trust the type annotation self._program can be either None or a QuantumProgram which is guaranteed to have a .code field of the any_pb2.Any type.

I was puzzled because or not self._program.code is effectively or False and thus redundant. I wondered if the intent was to have some non-const expression there so I suggested the value field. Otherwise I have no preference, dropping or not self._program.code would be fine with me too.

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@maffoo maffoo Jan 22, 2026

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Yes, it's the types of QuantumProgram itself that concerns me, because the proto-plus library does some metaclass magic so it's not clear to me how its type annotations work. I'd prefer to keep this for defense in depth for now.

self._program = await self.context.client.get_program_async(
self.project_id, self.program_id, True
)
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6 changes: 4 additions & 2 deletions cirq-google/cirq_google/engine/engine_program_test.py
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Expand Up @@ -298,12 +298,14 @@ def test_get_circuit_v1(get_program_async):


@mock.patch('cirq_google.engine.engine_client.EngineClient.get_program_async')
def test_get_circuit_v2(get_program_async):
@pytest.mark.parametrize("include_empty_program", [False, True])
def test_get_circuit_v2(get_program_async, include_empty_program: bool) -> None:
circuit = cirq.Circuit(
cirq.X(cirq.GridQubit(5, 2)) ** 0.5, cirq.measure(cirq.GridQubit(5, 2), key='result')
)

program = cg.EngineProgram('a', 'b', EngineContext())
program_msg = quantum.QuantumProgram() if include_empty_program else None
program = cg.EngineProgram('a', 'b', EngineContext(), _program=program_msg)
get_program_async.return_value = quantum.QuantumProgram(code=_PROGRAM_V2)
cirq.testing.assert_circuits_with_terminal_measurements_are_equivalent(
program.get_circuit(), circuit
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