Unroll circuit_op when validating containment in a gateset (quantumli…

…b#4770)

Fully unroll a circuit operation using `op.mapped_circuit(deep=True)` when checking containment of underlying operations in a gateset. This correctly handles circuit ops with negative reps, which lead to inverting all operations in the underlying circuit.  

Fixes quantumlib#4727.

cirq-core/cirq/ops/gateset.py

@@ -392,13 +392,7 @@ def _validate_operation(self, op: raw_types.Operation) -> bool:
         if isinstance(op, raw_types.TaggedOperation):
             return self._validate_operation(op.sub_operation)
         elif isinstance(op, circuit_operation.CircuitOperation) and self._unroll_circuit_op:
-            op_circuit = protocols.resolve_parameters(
-                op.circuit.unfreeze(), op.param_resolver, recursive=False
-            )
-            op_circuit = op_circuit.transform_qubits(
-                lambda q: cast(circuit_operation.CircuitOperation, op).qubit_map.get(q, q)
-            )
-            return self.validate(op_circuit)
+            return self.validate(op.mapped_circuit(deep=True))
         else:
             return False
 

cirq-core/cirq/ops/gateset_test.py

@@ -282,6 +282,13 @@ def assert_validate_and_contains_consistent(gateset, op_tree, result):
         )
 
 
+def test_gateset_validate_circuit_op_negative_reps():
+    gate = CustomXPowGate(exponent=0.5)
+    op = cirq.CircuitOperation(cirq.FrozenCircuit(gate.on(cirq.LineQubit(0))), repetitions=-1)
+    assert op not in cirq.Gateset(gate)
+    assert op ** -1 in cirq.Gateset(gate)
+
+
 def test_with_params():
     assert gateset.with_params() is gateset
     assert (