Fix for IndexError in an expression list assignment (#408)

There are some cases where the left and right hand sides of the
assignment don't have equal number of arguments. This change ensures the
node children have identical sizes to avoid this condition.

A longer term solution might be to handle star arguments.

Fixes #407

Signed-off-by: Eric Brown <eric.brown@securesauce.dev>

precli/parsers/python.py

@@ -92,6 +92,7 @@ def visit_assignment(self, nodes: list[Node]):
         if (
             nodes[0].type == tokens.PATTERN_LIST
             and nodes[2].type == tokens.EXPRESSION_LIST
+            and len(nodes[0].named_children) == len(nodes[2].named_children)
         ):
             for i in range(len(nodes[0].named_children)):
                 self.visit_assignment(

tests/unit/parsers/examples/expression_list_assignment.py

@@ -0,0 +1,6 @@
+import torch
+
+
+torch.tensor([[0.1, 1.2], [2.2, 3.1], [4.9, 5.2]])
+x = torch.tensor([[0.1, 1.2], [2.2, 3.1], [4.9, 5.2]])
+b, *_, device = *x.shape, x.device

tests/unit/parsers/test_python.py

@@ -19,6 +19,13 @@ def setUp(self):
             "examples",
         )
 
+    def test_expression_list_assignment(self):
+        artifact = Artifact(
+            os.path.join(self.base_path, "expression_list_assignment.py")
+        )
+        results = self.parser.parse(artifact)
+        self.assertEqual(0, len(results))
+
     def test_importlib_import_module(self):
         artifact = Artifact(
             os.path.join(self.base_path, "importlib_import_module.py")