Fix: Use update_instruction_properties instead of inplace replacement.

- Use `PyRef<Self>` for `__getitem__`
- Modify `generic_backend_v2` target generation.
- Modify test in `pulse_gate_pass`.

crates/accelerate/src/target_transpiler/mod.rs

@@ -907,21 +907,21 @@ impl Target {
     }
 
     /// Performs caching of python side dict objects for better access performance.
-    fn __getitem__(&mut self, key: &Bound<PyAny>) -> PyResult<PyObject> {
+    fn __getitem__(mut slf: PyRefMut<Self>, key: &Bound<PyAny>) -> PyResult<PyObject> {
         let py: Python = key.py();
         let Ok(key) = key.extract::<String>() else {return Err(PyKeyError::new_err(
             "Invalid Key Type for Target."
         ));};
-        if let Some(val) = self._py_gate_map_cache.get(key.as_str()) {
+        if let Some(val) = slf._py_gate_map_cache.get(key.as_str()) {
             Ok(val.as_any().clone_ref(py))
-        } else if let Some(val) = self.gate_map.get(key.as_str()) {
+        } else if let Some(val) = slf.gate_map.get(key.as_str()) {
             let new_py: Vec<(Option<Bound<'_, PyTuple>>, PyObject)> = val
                 .clone()
                 .into_iter()
                 .map(|(key, val)| (key.map(|key| PyTuple::new_bound(py, key)), val.into_py(py)))
                 .collect();
             let dict_py = new_py.into_py_dict_bound(py).unbind();
-            self._py_gate_map_cache.insert(key, dict_py.clone_ref(py));
+            slf._py_gate_map_cache.insert(key, dict_py.clone_ref(py));
             Ok(dict_py.into())
         } else {
             Err(PyKeyError::new_err(format!(

qiskit/providers/fake_provider/generic_backend_v2.py

@@ -489,7 +489,11 @@ def _add_noisy_instruction_to_target(
                 )
                 for qubit in qargs:
                     if qubit < self.num_qubits:
-                        self._target[instruction.name][(qubit,)].calibration = calibration_entry
+                        inst_prop = self._target[instruction.name][(qubit,)]
+                        inst_prop.calibration = calibration_entry
+                        self._target.update_instruction_properties(
+                            instruction.name, (qubit,), inst_prop
+                        )
 
     def run(self, run_input, **options):
         """Run on the backend using a simulator.

test/python/transpiler/test_pulse_gate_pass.py

@@ -143,8 +143,12 @@ def test_transpile_with_custom_basis_gate_in_target(self):
             seed=42,
         ).target
 
-        target["sx"][(0,)].calibration = self.custom_sx_q0
-        target["sx"][(1,)].calibration = self.custom_sx_q1
+        inst_prop_0 = target["sx"][(0,)]
+        inst_prop_0.calibration = self.custom_sx_q0
+        target.update_instruction_properties("sx", (0,), inst_prop_0)
+        inst_prop_1 = target["sx"][(1,)]
+        inst_prop_1.calibration = self.custom_sx_q1
+        target.update_instruction_properties("sx", (1,), inst_prop_1)
 
         qc = circuit.QuantumCircuit(2)
         qc.sx(0)