Recursive function calls shouldn't raise RecursionError

Store a stack of definitions.

If you revisit a function, treat it as a blackbox.

The non-recursive return values should still propagate.

Author: bcaller

pyt/cfg/expr_visitor.py

@@ -1,4 +1,5 @@
 import ast
+import logging
 
 from .alias_helper import handle_aliases_in_calls
 from ..core.ast_helper import (
@@ -30,6 +31,8 @@
 from .stmt_visitor import StmtVisitor
 from .stmt_visitor_helper import CALL_IDENTIFIER
 
+log = logging.getLogger(__name__)
+
 
 class ExprVisitor(StmtVisitor):
     def __init__(
@@ -52,6 +55,7 @@ def __init__(
         self.undecided = False
         self.function_names = list()
         self.function_return_stack = list()
+        self.function_definition_stack = list()  # used to avoid recursion
         self.module_definitions_stack = list()
         self.prev_nodes_to_avoid = list()
         self.last_control_flow_nodes = list()
@@ -543,6 +547,7 @@ def process_function(self, call_node, definition):
             first_node
         )
         self.function_return_stack.pop()
+        self.function_definition_stack.pop()
 
         return self.nodes[-1]
 
@@ -560,11 +565,15 @@ def visit_Call(self, node):
         last_attribute = _id.rpartition('.')[-1]
 
         if definition:
+            if definition in self.function_definition_stack:
+                log.debug("Recursion encountered in function %s", _id)
+                return self.add_blackbox_or_builtin_call(node, blackbox=True)
             if isinstance(definition.node, ast.ClassDef):
                 self.add_blackbox_or_builtin_call(node, blackbox=False)
             elif isinstance(definition.node, ast.FunctionDef):
                 self.undecided = False
                 self.function_return_stack.append(_id)
+                self.function_definition_stack.append(definition)
                 return self.process_function(node, definition)
             else:
                 raise Exception('Definition was neither FunctionDef or ' +

tests/cfg/cfg_test.py

@@ -3,6 +3,7 @@
 from .cfg_base_test_case import CFGBaseTestCase
 
 from pyt.core.node_types import (
+    BBorBInode,
     EntryOrExitNode,
     Node
 )
@@ -1389,6 +1390,13 @@ def test_call_on_call(self):
         path = 'examples/example_inputs/call_on_call.py'
         self.cfg_create_from_file(path)
 
+    def test_recursive_function(self):
+        path = 'examples/example_inputs/recursive.py'
+        self.cfg_create_from_file(path)
+        recursive_call = self.cfg.nodes[7]
+        assert recursive_call.label == '~call_3 = ret_rec(wat)'
+        assert isinstance(recursive_call, BBorBInode)  # Not RestoreNode
+
 
 class CFGCallWithAttributeTest(CFGBaseTestCase):
     def setUp(self):