deprecate BackendV1 in PassManagerConfig.from_backend

qiskit/transpiler/passmanager_config.py

@@ -13,6 +13,7 @@
 """Pass Manager Configuration class."""
 
 import pprint
+import warnings
 
 from qiskit.transpiler.coupling import CouplingMap
 from qiskit.transpiler.instruction_durations import InstructionDurations
@@ -113,11 +114,17 @@ def __init__(
     def from_backend(cls, backend, _skip_target=False, **pass_manager_options):
         """Construct a configuration based on a backend and user input.
 
-        This method automatically gererates a PassManagerConfig object based on the backend's
+        This method automatically generates a PassManagerConfig object based on the backend's
         features. User options can be used to overwrite the configuration.
 
+        .. deprecated:: 1.3
+            The method ``PassManagerConfig.from_backend`` will stop supporting inputs of type
+            :class:`.BackendV1` in the `backend` parameter in a future release no
+            earlier than 2.0. :class:`.BackendV1` is deprecated and implementations should move
+            to :class:`.BackendV2`.
+
         Args:
-            backend (BackendV1): The backend that provides the configuration.
+            backend (BackendV1 or BackendV2): The backend that provides the configuration.
             pass_manager_options: User-defined option-value pairs.
 
         Returns:
@@ -126,12 +133,21 @@ def from_backend(cls, backend, _skip_target=False, **pass_manager_options):
         Raises:
             AttributeError: If the backend does not support a `configuration()` method.
         """
-        res = cls(**pass_manager_options)
         backend_version = getattr(backend, "version", 0)
+        if backend_version == 1:
+            warnings.warn(
+                "The method PassManagerConfig.from_backend will stop supporting inputs of "
+                f"type `BackendV1` ( {backend} ) in the `backend` parameter in a future "
+                "release no earlier than 2.0. `BackendV1` is deprecated and implementations "
+                "should move to `BackendV2`.",
+                category=DeprecationWarning,
+                stacklevel=2,
+            )
         if not isinstance(backend_version, int):
             backend_version = 0
         if backend_version < 2:
             config = backend.configuration()
+        res = cls(**pass_manager_options)
         if res.basis_gates is None:
             if backend_version < 2:
                 res.basis_gates = getattr(config, "basis_gates", None)

releasenotes/notes/followup_12629-8bfcf1a3d4e6cabf.yaml

@@ -0,0 +1,6 @@
+---
+deprecations_transpiler:
+  - |
+    The method :meth:`.PassManagerConfig.from_backend` will stop supporting inputs of type
+    :class:`.BackendV1` in the `backend` parameter in a future release no earlier than 2.0.
+    :class:`.BackendV1` is deprecated and implementations should move to :class:`.BackendV2`.

test/python/primitives/test_backend_estimator_v2.py

@@ -145,7 +145,10 @@ def test_estimator_run_v1(self, backend, abelian_grouping):
         ):
             pm = generate_preset_pass_manager(optimization_level=0, backend=backend)
         psi1, psi2 = pm.run([psi1, psi2])
-        estimator = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            estimator = BackendEstimatorV2(backend=backend, options=self._options)
         estimator.options.abelian_grouping = abelian_grouping
         # Specify the circuit and observable by indices.
         # calculate [ <psi1(theta1)|H1|psi1(theta1)> ]
@@ -235,7 +238,10 @@ def test_estimator_with_pub_v1(self, backend, abelian_grouping):
         bind2 = BindingsArray.coerce({tuple(psi2.parameters): theta2})
         pub2 = EstimatorPub(psi2, obs2, bind2)
 
-        estimator = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            estimator = BackendEstimatorV2(backend=backend, options=self._options)
         estimator.options.abelian_grouping = abelian_grouping
         result4 = estimator.run([pub1, pub2]).result()
         np.testing.assert_allclose(result4[0].data.evs, [1.55555728, -1.08766318], rtol=self._rtol)
@@ -264,7 +270,10 @@ def test_estimator_run_no_params_v1(self, backend, abelian_grouping):
         ):
             pm = generate_preset_pass_manager(optimization_level=0, backend=backend)
         circuit = pm.run(circuit)
-        est = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            est = BackendEstimatorV2(backend=backend, options=self._options)
         est.options.abelian_grouping = abelian_grouping
         observable = self.observable.apply_layout(circuit.layout)
         result = est.run([(circuit, observable)]).result()
@@ -331,7 +340,13 @@ def test_run_single_circuit_observable(self, backend, abelian_grouping):
     @combine(backend=BACKENDS_V1, abelian_grouping=[True, False])
     def test_run_single_circuit_observable_v1(self, backend, abelian_grouping):
         """Test for single circuit and single observable case."""
-        est = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarnsRegex(
+            DeprecationWarning,
+            expected_regex=r"The method PassManagerConfig\.from_backend will stop supporting inputs of "
+            "type `BackendV1`",
+        ):
+            # BackendEstimatorV2 wont allow BackendV1
+            est = BackendEstimatorV2(backend=backend, options=self._options)
         est.options.abelian_grouping = abelian_grouping
         with self.assertWarnsRegex(
             DeprecationWarning,
@@ -438,7 +453,11 @@ def test_run_1qubit_v1(self, backend, abelian_grouping):
         op = SparsePauliOp.from_list([("I", 1)])
         op2 = SparsePauliOp.from_list([("Z", 1)])
 
-        est = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            est = BackendEstimatorV2(backend=backend, options=self._options)
+
         est.options.abelian_grouping = abelian_grouping
         op_1 = op.apply_layout(qc.layout)
         result = est.run([(qc, op_1)]).result()
@@ -513,7 +532,10 @@ def test_run_2qubits_v1(self, backend, abelian_grouping):
         op2 = SparsePauliOp.from_list([("ZI", 1)])
         op3 = SparsePauliOp.from_list([("IZ", 1)])
 
-        est = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            est = BackendEstimatorV2(backend=backend, options=self._options)
         est.options.abelian_grouping = abelian_grouping
         op_1 = op.apply_layout(qc.layout)
         result = est.run([(qc, op_1)]).result()
@@ -539,7 +561,47 @@ def test_run_2qubits_v1(self, backend, abelian_grouping):
         result = est.run([(qc2, op_6)]).result()
         np.testing.assert_allclose(result[0].data.evs, [-1], rtol=self._rtol)
 
-    @combine(backend=BACKENDS, abelian_grouping=[True, False])
+    @combine(backend=BACKENDS_V1, abelian_grouping=[True, False])
+    def test_run_errors_v1(self, backend, abelian_grouping):
+        """Test for errors.
+        To be removed once BackendV1 is removed."""
+        qc = QuantumCircuit(1)
+        qc2 = QuantumCircuit(2)
+
+        op = SparsePauliOp.from_list([("I", 1)])
+        op2 = SparsePauliOp.from_list([("II", 1)])
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            est = BackendEstimatorV2(backend=backend, options=self._options)
+        est.options.abelian_grouping = abelian_grouping
+        with self.assertRaises(ValueError):
+            est.run([(qc, op2)]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, op, [[1e4]])]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc2, op2, [[1, 2]])]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, [op, op2], [[1]])]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, op)], precision=-1).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, 1j * op)], precision=0.1).result()
+        # precision == 0
+        with self.assertRaises(ValueError):
+            est.run([(qc, op, None, 0)]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, op)], precision=0).result()
+        # precision < 0
+        with self.assertRaises(ValueError):
+            est.run([(qc, op, None, -1)]).result()
+        with self.assertRaises(ValueError):
+            est.run([(qc, op)], precision=-1).result()
+        with self.subTest("missing []"):
+            with self.assertRaisesRegex(ValueError, "An invalid Estimator pub-like was given"):
+                _ = est.run((qc, op)).result()
+
+    @combine(backend=BACKENDS_V2, abelian_grouping=[True, False])
     def test_run_errors(self, backend, abelian_grouping):
         """Test for errors"""
         qc = QuantumCircuit(1)
@@ -624,7 +686,13 @@ def test_run_numpy_params_v1(self, backend, abelian_grouping):
         statevector_estimator = StatevectorEstimator(seed=123)
         target = statevector_estimator.run([(qc, op, params_list)]).result()
 
-        backend_estimator = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarnsRegex(
+            DeprecationWarning,
+            expected_regex=r"The method PassManagerConfig\.from_backend will stop supporting inputs of "
+            "type `BackendV1`",
+        ):
+            # BackendEstimatorV2 wont allow BackendV1
+            backend_estimator = BackendEstimatorV2(backend=backend, options=self._options)
         backend_estimator.options.abelian_grouping = abelian_grouping
 
         with self.subTest("ndarrary"):
@@ -662,7 +730,10 @@ def test_precision(self, backend, abelian_grouping):
     @combine(backend=BACKENDS_V1, abelian_grouping=[True, False])
     def test_precision_v1(self, backend, abelian_grouping):
         """Test for precision"""
-        estimator = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            estimator = BackendEstimatorV2(backend=backend, options=self._options)
         estimator.options.abelian_grouping = abelian_grouping
         with self.assertWarnsRegex(
             DeprecationWarning,
@@ -705,7 +776,10 @@ def test_diff_precision(self, backend, abelian_grouping):
     @combine(backend=BACKENDS_V1, abelian_grouping=[True, False])
     def test_diff_precision_v1(self, backend, abelian_grouping):
         """Test for running different precisions at once"""
-        estimator = BackendEstimatorV2(backend=backend, options=self._options)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            estimator = BackendEstimatorV2(backend=backend, options=self._options)
         estimator.options.abelian_grouping = abelian_grouping
         with self.assertWarnsRegex(
             DeprecationWarning,
@@ -792,7 +866,10 @@ def test_job_size_limit_backend_v1(self):
         op = SparsePauliOp.from_list([("IZ", 1), ("XI", 2), ("ZY", -1)])
         k = 5
         param_list = self._rng.random(qc.num_parameters).tolist()
-        estimator = BackendEstimatorV2(backend=backend)
+        with self.assertWarns(DeprecationWarning):
+            # When BackendEstimatorV2 is called with a backend V1, it raises a
+            # DeprecationWarning from PassManagerConfig.from_backend
+            estimator = BackendEstimatorV2(backend=backend)
         with patch.object(backend, "run") as run_mock:
             estimator.run([(qc, op, param_list)] * k).result()
         self.assertEqual(run_mock.call_count, 10)

test/python/transpiler/test_passmanager_config.py

@@ -33,7 +33,7 @@ def test_config_from_backend(self):
         """
         with self.assertWarns(DeprecationWarning):
             backend = Fake27QPulseV1()
-        config = PassManagerConfig.from_backend(backend)
+            config = PassManagerConfig.from_backend(backend)
         self.assertEqual(config.basis_gates, backend.configuration().basis_gates)
         self.assertEqual(config.inst_map, backend.defaults().instruction_schedule_map)
         self.assertEqual(
@@ -66,9 +66,9 @@ def test_from_backend_and_user_v1(self):
 
         with self.assertWarns(DeprecationWarning):
             backend = Fake20QV1()
-        config = PassManagerConfig.from_backend(
-            backend, basis_gates=["user_gate"], initial_layout=initial_layout
-        )
+            config = PassManagerConfig.from_backend(
+                backend, basis_gates=["user_gate"], initial_layout=initial_layout
+            )
         self.assertEqual(config.basis_gates, ["user_gate"])
         self.assertNotEqual(config.basis_gates, backend.configuration().basis_gates)
         self.assertIsNone(config.inst_map)
@@ -107,7 +107,8 @@ def test_from_backendv1_inst_map_is_none(self):
         with self.assertWarns(DeprecationWarning):
             backend = Fake27QPulseV1()
         backend.defaults = lambda: None
-        config = PassManagerConfig.from_backend(backend)
+        with self.assertWarns(DeprecationWarning):
+            config = PassManagerConfig.from_backend(backend)
         self.assertIsInstance(config, PassManagerConfig)
         self.assertIsNone(config.inst_map)