docs(transpiler-plugins): fix layout plugin example for v2.1.2 (Qiskit#14985) (Qiskit#14991) (Qiskit#15103)

* docs(transpiler-plugins): fix layout plugin example for v2.1.2 (Qiskit#14985)

Fixes Qiskit#14985 issue.

Updates the example under `qiskit.transpiler.preset_passmanagers.plugin`
so it runs on Qiskit SDK v2.1.2.

- Replace `PassManager.append(..., condition=...)` with `ConditionalController`.
- Remove usage of `backend_properties` from `PassManagerConfig`.
- Pass `target=pass_manager_config.target` to `VF2Layout`.
- Add the missing comma in `max_trials=...`.
- Guard property_set lookups with `.get(...)` and check against
  `VF2LayoutStopReason.SOLUTION_FOUND`.

Tested with `generate_preset_pass_manager(..., layout_method="vf2lite")`
at `optimization_level=1..3` on SDK v2.1.2.

* Fix lint error in plugin.py docstring (line too long)

* Fix spacing

---------


(cherry picked from commit cbe1f20)

Co-authored-by: Ricard Santiago Raigada García <[email protected]>
Co-authored-by: Jake Lishman <[email protected]>

Author: 3 people

qiskit/transpiler/preset_passmanagers/plugin.py

@@ -103,31 +103,32 @@
     from qiskit.transpiler import PassManager
     from qiskit.transpiler.passes import VF2Layout, TrivialLayout
     from qiskit.transpiler.passes.layout.vf2_layout import VF2LayoutStopReason
+    from qiskit.passmanager import ConditionalController
 
 
     def _vf2_match_not_found(property_set):
-        return property_set["layout"] is None or (
-            property_set["VF2Layout_stop_reason"] is not None
-            and property_set["VF2Layout_stop_reason"] is not VF2LayoutStopReason.SOLUTION_FOUND
+        return property_set.get("layout") is None or (
+            property_set.get("VF2Layout_stop_reason") is not None
+            and property_set.get("VF2Layout_stop_reason")
+            is not VF2LayoutStopReason.SOLUTION_FOUND
+        )
 
 
     class VF2LayoutPlugin(PassManagerStagePlugin):
-
         def pass_manager(self, pass_manager_config, optimization_level):
             layout_pm = PassManager(
                 [
                     VF2Layout(
                         coupling_map=pass_manager_config.coupling_map,
-                        properties=pass_manager_config.backend_properties,
-                        max_trials=optimization_level * 10 + 1
-                        target=pass_manager_config.target
-                    )
+                        max_trials=optimization_level * 10 + 1,
+                        target=pass_manager_config.target,
+                    ),
+                    ConditionalController(
+                        TrivialLayout(pass_manager_config.coupling_map),
+                        condition=_vf2_match_not_found,
+                    ),
                 ]
             )
-            layout_pm.append(
-                TrivialLayout(pass_manager_config.coupling_map),
-                condition=_vf2_match_not_found,
-            )
             layout_pm += common.generate_embed_passmanager(pass_manager_config.coupling_map)
             return layout_pm