Remove previously deprecated fields in cirq_google proto (#7183)

* Remove previously deprecated fields in cirq_google proto

- Removes schedule (not used in 5+ years)
- Removes gate and args (not used since v2.5, 3+ years)
- Removes checks on gate set and language.
- Removes tests that use the above.

* Take care of deprecated usage in test.

* Another broken test.

* Remove another test

* Remove engine test with bad gateset

* Put back test.

* Add back lint issue.

---------

Co-authored-by: Pavol Juhas <juhas@google.com>

Author: dstrain115

cirq-google/cirq_google/api/v2/program.proto

@@ -19,12 +19,11 @@ message Program {
     // moment having a set of gates that act on disjoint qubits. Circuits don't
     // have absolute times for their operations (gates acting on qubits).
     Circuit circuit = 2;
-
-    // Schedules are a list of operations (gates acting on qubits) that specify
-    // absolute start times for the operations.
-    Schedule schedule = 3;
   }
 
+  // Previously deprecated field.  Do not use.
+  reserved 3;
+
   // List to store global constants, such as strings used in many places.
   // constants are referred to their index in this list, starting at zero.
   repeated Constant constants = 4;
@@ -105,25 +104,6 @@ message Moment {
   reserved 3;
 }
 
-// The quantum circuit, specified as a series of operations at specific
-// start times.
-message Schedule {
-  // A list of all the operations and their absolute start times.
-  repeated ScheduledOperation scheduled_operations = 3;
-}
-
-// An operation occurring at a specific start time.
-message ScheduledOperation {
-  // Which operation is to be scheduled.
-  Operation operation = 1;
-
-  // The start time of the operation, with zero representing the absolute
-  // start of the circuit.
-  //
-  // This must be consistent with the moment structure and must be positive.
-  int64 start_time_picos = 2;
-}
-
 // The language in which the program is expressed.
 message Language {
   // The name of the gate set being used.
@@ -223,9 +203,8 @@ message WaitGate {
 
 // An operation acts on a set of qubits.
 message Operation {
-  // Which gate this operation corresponds to.
-  // Populated pre-v2.5+.
-  Gate gate = 1 [deprecated = true];
+  // Previously deprecated fields.  Do not use.
+  reserved 1, 2;
 
   // Each gate should populate one possible gate message
   // depending on the type desired.  Only populated in v2.5+.
@@ -248,17 +227,13 @@ message Operation {
     ResetGate resetgate = 24;
   }
 
-  // Map from the argument name to the Argument needed to fully specify
-  // the gate. Only populated pre-v2.5+.
-  map<string, Arg> args = 2 [deprecated = true];
-
   // Which qubits the operation acts on.
   // Operations should populate one of the following two
   // fields: either to specify the qubit directly or
   // to reference an index in the enclosing Program's
   // constant messages.  Note that qubit_constant_index
   // will only be populated in v2.5+
-  repeated Qubit qubits = 3;
+  repeated Qubit qubits = 3 [deprecated = true];
   repeated int32 qubit_constant_index = 6;
 
   // Token that can be used to specify a version of a gate.

cirq-google/cirq_google/api/v2/program_pb2.py

@@ -316,19 +316,6 @@ def mock_grpc_client():
         yield _fixture
 
 
-@mock.patch('cirq_google.engine.engine_client.EngineClient.get_program_async')
-def test_get_circuit_v2_unknown_gateset(get_program_async):
-    program = cg.EngineProgram('a', 'b', EngineContext())
-    get_program_async.return_value = quantum.QuantumProgram(
-        code=util.pack_any(
-            v2.program_pb2.Program(language=v2.program_pb2.Language(gate_set="BAD_GATESET"))
-        )
-    )
-
-    with pytest.raises(ValueError, match='BAD_GATESET'):
-        program.get_circuit()
-
-
 @mock.patch('cirq_google.engine.engine_client.EngineClient.get_program_async')
 def test_get_circuit_unsupported_program_type(get_program_async):
     program = cg.EngineProgram('a', 'b', EngineContext())

cirq-google/cirq_google/api/v2/program_pb2.pyi

@@ -391,12 +391,6 @@ def deserialize(self, proto: v2.program_pb2.Program) -> cirq.Circuit:
                 a schedule is attempted.
             NotImplementedError: If the program proto does not contain a circuit or schedule.
         """
-        if not proto.HasField('language') or not proto.language.gate_set:
-            raise ValueError('Missing gate set specification.')
-        if proto.language.gate_set != self.name:
-            raise ValueError(
-                f'Gate set in proto was {proto.language.gate_set} but expected {self.name}'
-            )
         which = proto.WhichOneof('program')
 
         if which == 'circuit':

cirq-google/cirq_google/engine/engine_program_test.py

@@ -680,18 +680,6 @@ def test_serialize_unrecognized():
         serializer.serialize("not quite right")
 
 
-def default_circuit_proto():
-    op1 = v2.program_pb2.Operation()
-    op1.gate.id = 'x_pow'
-    op1.args['half_turns'].arg_value.string_value = 'k'
-    op1.qubits.add().id = '1_1'
-
-    return v2.program_pb2.Circuit(
-        scheduling_strategy=v2.program_pb2.Circuit.MOMENT_BY_MOMENT,
-        moments=[v2.program_pb2.Moment(operations=[op1])],
-    )
-
-
 def default_circuit():
     return cirq.FrozenCircuit(
         cirq.X(cirq.GridQubit(1, 1)) ** sympy.Symbol('k'),
@@ -701,7 +689,7 @@ def default_circuit():
 
 def test_serialize_circuit_op_errors():
     serializer = cg.CircuitSerializer()
-    constants = [default_circuit_proto()]
+    constants = [serializer.serialize(default_circuit()).circuit]
     raw_constants = {default_circuit(): 0}
 
     op = cirq.CircuitOperation(default_circuit())
@@ -715,26 +703,6 @@ def test_serialize_circuit_op_errors():
         serializer._serialize_circuit_op(op, raw_constants=raw_constants)
 
 
-def test_deserialize_unsupported_gate_type():
-    serializer = cg.CircuitSerializer()
-    operation_proto = op_proto(
-        {
-            'gate': {'id': 'no_pow'},
-            'args': {'half_turns': {'arg_value': {'float_value': 0.125}}},
-            'qubits': [{'id': '1_1'}],
-        }
-    )
-    proto = v2.program_pb2.Program(
-        language=v2.program_pb2.Language(arg_function_language='', gate_set=_SERIALIZER_NAME),
-        circuit=v2.program_pb2.Circuit(
-            scheduling_strategy=v2.program_pb2.Circuit.MOMENT_BY_MOMENT,
-            moments=[v2.program_pb2.Moment(operations=[operation_proto])],
-        ),
-    )
-    with pytest.raises(ValueError, match='no_pow'):
-        serializer.deserialize(proto)
-
-
 def test_serialize_op_unsupported_type():
     serializer = cg.CircuitSerializer()
     q0 = cirq.GridQubit(1, 1)
@@ -759,42 +727,6 @@ def with_qubits(self, *qubits):
         serializer.serialize(cirq.Circuit(null_op))
 
 
-def test_deserialize_invalid_gate_set():
-    serializer = cg.CircuitSerializer()
-    proto = v2.program_pb2.Program(
-        language=v2.program_pb2.Language(gate_set='not_my_gate_set'),
-        circuit=v2.program_pb2.Circuit(
-            scheduling_strategy=v2.program_pb2.Circuit.MOMENT_BY_MOMENT, moments=[]
-        ),
-    )
-    with pytest.raises(ValueError, match='not_my_gate_set'):
-        serializer.deserialize(proto)
-
-    proto.language.gate_set = ''
-    with pytest.raises(ValueError, match='Missing gate set'):
-        serializer.deserialize(proto)
-
-    proto = v2.program_pb2.Program(
-        circuit=v2.program_pb2.Circuit(
-            scheduling_strategy=v2.program_pb2.Circuit.MOMENT_BY_MOMENT, moments=[]
-        )
-    )
-    with pytest.raises(ValueError, match='Missing gate set'):
-        serializer.deserialize(proto)
-
-
-def test_deserialize_schedule_not_supported():
-    serializer = cg.CircuitSerializer()
-    proto = v2.program_pb2.Program(
-        language=v2.program_pb2.Language(gate_set=_SERIALIZER_NAME),
-        schedule=v2.program_pb2.Schedule(
-            scheduled_operations=[v2.program_pb2.ScheduledOperation(start_time_picos=0)]
-        ),
-    )
-    with pytest.raises(ValueError, match='no longer supported'):
-        serializer.deserialize(proto)
-
-
 def test_deserialize_fsim_missing_parameters():
     serializer = cg.CircuitSerializer()
     proto = circuit_proto(