Deprecate inner_transform_program and config arguments to qml.execute

doc/development/deprecations.rst

@@ -9,6 +9,12 @@ deprecations are listed below.
 Pending deprecations
 --------------------
 
+* The ``inner_transform_program`` and ``config`` keyword arguments in ``qml.execute`` has been deprecated.
+  Instead, use ``qml.run`` with these arguments for a more detailed control over the execution.
+
+  - Deprecated in v0.41
+  - Will be removed in v0.42
+
 * The ``qsvt_legacy`` function has been deprecated.
   Instead, use ``qml.qsvt``. The new functionality takes an input polynomial instead of angles.
 

doc/releases/changelog-dev.md

@@ -10,6 +10,10 @@
 
 <h3>Deprecations 👋</h3>
 
+* The ``inner_transform_program`` and ``config`` keyword arguments in ``qml.execute`` has been deprecated.
+  Instead, use ``qml.run`` with these arguments for a more detailed control over the execution.
+  [(#6822)](https://github.com/PennyLaneAI/pennylane/pull/6822)
+
 <h3>Documentation 📝</h3>
 
 * Updated documentation for vibrational Hamiltonians

pennylane/workflow/execution.py

@@ -45,15 +45,15 @@ def execute(
     diff_method: Optional[Union[Callable, str, qml.transforms.core.TransformDispatcher]] = None,
     interface: Optional[Union[str, Interface]] = Interface.AUTO,
     transform_program=None,
-    inner_transform=None,
-    config=None,
     grad_on_execution="best",
     gradient_kwargs=None,
     cache: Union[None, bool, dict, Cache] = True,
     cachesize=10000,
     max_diff=1,
     device_vjp=False,
     mcm_config=None,
+    config="unset",
+    inner_transform="unset",
     gradient_fn="unset",
 ) -> ResultBatch:
     """A function for executing a batch of tapes on a device with compatibility for auto-differentiation.
@@ -70,10 +70,6 @@ def execute(
             This affects the types of parameters that can exist on the input tapes.
             Available options include ``autograd``, ``torch``, ``tf``, ``jax``, and ``auto``.
         transform_program(.TransformProgram): A transform program to be applied to the initial tape.
-        inner_transform (.TransformProgram): A transform program to be applied to the tapes in
-            inner execution, inside the ml interface.
-        config (qml.devices.ExecutionConfig): A data structure describing the parameters
-            needed to fully describe the execution.
         grad_on_execution (bool, str): Whether the gradients should be computed
             on the execution or not. It only applies
             if the device is queried for the gradient; gradient transform
@@ -92,6 +88,10 @@ def execute(
             product if it is available.
         mcm_config (dict): Dictionary containing configuration options for handling
             mid-circuit measurements.
+        config="unset": **DEPRECATED**. This keyword argument has been deprecated and
+            will be removed in v0.42.
+        inner_transform="unset": **DEPRECATED**. This keyword argument has been deprecated
+            and will be removed in v0.42.
         gradient_fn="unset": **DEPRECATED**.  This keyword argument has been renamed
             ``diff_method`` and will be removed in v0.41.
 
@@ -164,6 +164,20 @@ def cost_fn(params, x):
         )
         diff_method = gradient_fn
 
+    if config != "unset":
+        warn(
+            "The config argument has been deprecated and will be removed in v0.42. \
+            Instead, use qml.run with these arguments for a more detailed control over the execution.",
+            qml.PennyLaneDeprecationWarning,
+        )
+
+    if inner_transform != "unset":
+        warn(
+            "The inner_transform argument has been deprecated and will be removed in v0.42. \
+            Instead, use qml.run with these arguments for a more detailed control over the execution.",
+            qml.PennyLaneDeprecationWarning,
+        )
+
     if logger.isEnabledFor(logging.DEBUG):
         logger.debug(
             (
@@ -195,33 +209,27 @@ def cost_fn(params, x):
     interface = _resolve_interface(interface, tapes)
     # Only need to calculate derivatives with jax when we know it will be executed later.
 
-    gradient_kwargs = gradient_kwargs or {}
-    mcm_config = mcm_config or {}
-    if not config:
-        config = qml.devices.ExecutionConfig(
-            interface=interface,
-            gradient_method=diff_method,
-            grad_on_execution=None if grad_on_execution == "best" else grad_on_execution,
-            use_device_jacobian_product=device_vjp,
-            mcm_config=mcm_config,
-            gradient_keyword_arguments=gradient_kwargs,
-            derivative_order=max_diff,
-        )
-        config = _resolve_execution_config(
-            config, device, tapes, transform_program=transform_program
-        )
+    config = qml.devices.ExecutionConfig(
+        interface=interface,
+        gradient_method=diff_method,
+        grad_on_execution=None if grad_on_execution == "best" else grad_on_execution,
+        use_device_jacobian_product=device_vjp,
+        mcm_config=mcm_config or {},
+        gradient_keyword_arguments=gradient_kwargs or {},
+        derivative_order=max_diff,
+    )
+    config = _resolve_execution_config(config, device, tapes, transform_program=transform_program)
 
     config = replace(
         config,
         interface=interface,
         derivative_order=max_diff,
     )
 
-    if transform_program is None or inner_transform is None:
-        transform_program = transform_program or qml.transforms.core.TransformProgram()
-        transform_program, inner_transform = _setup_transform_program(
-            transform_program, device, config, cache, cachesize
-        )
+    transform_program = transform_program or qml.transforms.core.TransformProgram()
+    transform_program, inner_transform = _setup_transform_program(
+        transform_program, device, config, cache, cachesize
+    )
 
     #### Executing the configured setup #####
     tapes, post_processing = transform_program(tapes)

tests/workflow/interfaces/execute/test_execute.py

@@ -72,6 +72,28 @@ def test_gradient_fn_deprecation():
     assert dev.tracker.totals["execute_and_derivative_batches"] == 1  # uses adjoint diff
 
 
+def test_config_deprecation():
+    """Test that the config argument has been deprecated."""
+
+    tape = qml.tape.QuantumScript([qml.RX(qml.numpy.array(1.0), 0)], [qml.expval(qml.Z(0))])
+    dev = qml.device("default.qubit")
+    with pytest.warns(
+        qml.PennyLaneDeprecationWarning, match="The config argument has been deprecated"
+    ):
+        qml.execute((tape,), dev, config=qml.devices.DefaultExecutionConfig)
+
+
+def test_inner_transform_program_deprecation():
+    """Test that the inner_transform argument has been deprecated."""
+
+    tape = qml.tape.QuantumScript([qml.RX(qml.numpy.array(1.0), 0)], [qml.expval(qml.Z(0))])
+    dev = qml.device("default.qubit")
+    with pytest.warns(
+        qml.PennyLaneDeprecationWarning, match="The inner_transform argument has been deprecated"
+    ):
+        qml.execute((tape,), dev, inner_transform=qml.transforms.core.TransformProgram())
+
+
 def test_execution_with_empty_batch():
     """Test that qml.execute can be used with an empty batch."""