Add TranspileErrors to routing passes for coupling_map=None (Qiskit#7141

)

* Adding TranspileErrors to routing passes that run with coupling_map=None

* Add changelog

---------

Co-authored-by: Matthew Treinish <[email protected]>

qiskit/transpiler/passes/routing/basic_swap.py

@@ -50,13 +50,16 @@ def run(self, dag):
 
         Raises:
             TranspilerError: if the coupling map or the layout are not
-            compatible with the DAG.
+            compatible with the DAG, or if the coupling_map=None.
         """
         if self.fake_run:
             return self.fake_run(dag)
 
         new_dag = dag.copy_empty_like()
 
+        if self.coupling_map is None:
+            raise TranspilerError("BasicSwap cannot run with coupling_map=None")
+
         if len(dag.qregs) != 1 or dag.qregs.get("q", None) is None:
             raise TranspilerError("Basic swap runs on physical circuits only")
 

qiskit/transpiler/passes/routing/lookahead_swap.py

@@ -108,8 +108,12 @@ def run(self, dag):
                 the property_set.
         Raises:
             TranspilerError: if the coupling map or the layout are not
-            compatible with the DAG
+            compatible with the DAG, or if the coupling_map=None
         """
+
+        if self.coupling_map is None:
+            raise TranspilerError("LookaheadSwap cannot run with coupling_map=None")
+
         if len(dag.qregs) != 1 or dag.qregs.get("q", None) is None:
             raise TranspilerError("Lookahead swap runs on physical circuits only")
 

qiskit/transpiler/passes/routing/sabre_swap.py

@@ -174,8 +174,12 @@ def run(self, dag):
             DAGCircuit: A dag mapped to be compatible with the coupling_map.
         Raises:
             TranspilerError: if the coupling map or the layout are not
-            compatible with the DAG
+            compatible with the DAG, or if the coupling_map=None
         """
+
+        if self.coupling_map is None:
+            raise TranspilerError("SabreSwap cannot run with coupling_map=None")
+
         if len(dag.qregs) != 1 or dag.qregs.get("q", None) is None:
             raise TranspilerError("Sabre swap runs on physical circuits only.")
 

qiskit/transpiler/passes/routing/stochastic_swap.py

@@ -86,9 +86,12 @@ def run(self, dag):
 
         Raises:
             TranspilerError: if the coupling map or the layout are not
-            compatible with the DAG
+            compatible with the DAG, or if the coupling_map=None
         """
 
+        if self.coupling_map is None:
+            raise TranspilerError("StochasticSwap cannot run with coupling_map=None")
+
         if len(dag.qregs) != 1 or dag.qregs.get("q", None) is None:
             raise TranspilerError("StochasticSwap runs on physical circuits only")
 

releasenotes/notes/fix-routing-passes-for-none-coupling_map-c4dd53594a9ef645.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Throw ``TranspileError`` when routing passes (``StochasticSwap``, ``SabreSwap``, 
+    ``LookaheadSwap``, and ``BasicSwap``) run with ``coupling_map=None``. Refer to
+    `#7127 <https://github.com/Qiskit/qiskit-terra/issues/7127>` for more details.