execute(..., backend=..., passmanager=...) has not conflicting args (#…

…5051)

* exclude backend from _check_conflicting_argument

* test

* reno

Co-authored-by: Kevin Krsulich <kevin.krsulich@ibm.com>

qiskit/execute.py

@@ -243,8 +243,7 @@ def execute(experiments, backend,
                                     coupling_map=coupling_map,
                                     seed_transpiler=seed_transpiler,
                                     backend_properties=backend_properties,
-                                    initial_layout=initial_layout,
-                                    backend=backend)
+                                    initial_layout=initial_layout)
         experiments = pass_manager.run(experiments)
     else:
         # transpiling the circuits using given transpile options

releasenotes/notes/5037-e73ce50c4ae23445.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    The parameters `backend` and `passmanager` in :func:`qiskit.execute.execute`
+    are not conflicting and they are simultaneously allowed now.

test/python/compiler/test_compiler.py

@@ -170,6 +170,18 @@ def test_parallel_compile(self):
         qobj = assemble(transpile(qlist, backend=backend))
         self.assertEqual(len(qobj.experiments), 10)
 
+    def test_no_conflict_backend_passmanager(self):
+        """execute(qc, backend=..., passmanager=...)
+        See: https://github.com/Qiskit/qiskit-terra/issues/5037
+        """
+        backend = BasicAer.get_backend('qasm_simulator')
+        qc = QuantumCircuit(2)
+        qc.u1(0, 0)
+        qc.measure_all()
+        job = execute(qc, backend=backend, pass_manager=PassManager())
+        result = job.result().get_counts()
+        self.assertEqual(result, {'00': 1024})
+
     def test_compile_single_qubit(self):
         """ Compile a single-qubit circuit in a non-trivial layout
         """