⚡ Bolt: [performance improvement] Optimize iter_calls_in_function_body for faster AST traversal

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-06-25 - AST Node Iteration Traversal Optimization
+**Learning:** AST traversal with recursive generators (`yield from`) and `ast.iter_child_nodes()` creates significant overhead due to multiple generator frames. This is especially true for hot-path traversals.
+**Action:** Use an explicit stack instead of `yield from` recursion to preserve lazy evaluation and short-circuiting capabilities. Avoid eager list-appending (`list.append()`) to prevent computing the whole subtree when early matches exist. Reverse child nodes via `reversed()` before extending the stack to preserve traversal order. Critically, retain `isinstance(node, ast.AST)` checks to prevent `AttributeError`s when traversing `_fields`, as not all field values are AST nodes (some are strings or literals).

src/wardline/scanner/ast_primitives.py

@@ -104,39 +104,61 @@ def iter_calls_in_function_body(
     Header expressions that execute in the enclosing scope (decorators, default
     values, base classes, metaclass keywords) are still attributed to ``node``.
     """
+    stack: list[ast.AST] = list(reversed(node.body))
+    while stack:
+        current = stack.pop()
 
-    def walk_node(current: ast.AST) -> Iterator[ast.Call]:
         if isinstance(current, (ast.FunctionDef, ast.AsyncFunctionDef)):
-            for decorator in current.decorator_list:
-                yield from walk_node(decorator)
-            yield from _walk_argument_defaults(current.args)
-            return
+            kw_defaults = current.args.kw_defaults
+            for i in range(len(kw_defaults) - 1, -1, -1):
+                val = kw_defaults[i]
+                if val is not None:
+                    stack.append(val)
+            defaults = current.args.defaults
+            for i in range(len(defaults) - 1, -1, -1):
+                stack.append(defaults[i])
+            decorators = current.decorator_list
+            for i in range(len(decorators) - 1, -1, -1):
+                stack.append(decorators[i])
+            continue
+
         if isinstance(current, ast.ClassDef):
-            for decorator in current.decorator_list:
-                yield from walk_node(decorator)
-            for base in current.bases:
-                yield from walk_node(base)
-            for keyword in current.keywords:
-                yield from walk_node(keyword.value)
-            return
+            keywords = current.keywords
+            for i in range(len(keywords) - 1, -1, -1):
+                stack.append(keywords[i].value)
+            bases = current.bases
+            for i in range(len(bases) - 1, -1, -1):
+                stack.append(bases[i])
+            decorators = current.decorator_list
+            for i in range(len(decorators) - 1, -1, -1):
+                stack.append(decorators[i])
+            continue
+
         if isinstance(current, ast.Lambda):
-            yield from _walk_argument_defaults(current.args)
-            return
+            kw_defaults = current.args.kw_defaults
+            for i in range(len(kw_defaults) - 1, -1, -1):
+                val = kw_defaults[i]
+                if val is not None:
+                    stack.append(val)
+            defaults = current.args.defaults
+            for i in range(len(defaults) - 1, -1, -1):
+                stack.append(defaults[i])
+            continue
+
         if isinstance(current, ast.Call):
             yield current
-        for child in ast.iter_child_nodes(current):
-            yield from walk_node(child)
-
-    def _walk_argument_defaults(args: ast.arguments) -> Iterator[ast.Call]:
-        for default in args.defaults:
-            yield from walk_node(default)
-        for kw_default in args.kw_defaults:
-            if kw_default is None:
-                continue
-            yield from walk_node(kw_default)
 
-    for stmt in node.body:
-        yield from walk_node(stmt)
+        for field in reversed(current._fields):
+            try:
+                value = getattr(current, field)
+            except AttributeError:
+                continue
+            if isinstance(value, list):
+                for item in reversed(value):
+                    if isinstance(item, ast.AST):
+                        stack.append(item)
+            elif isinstance(value, ast.AST):
+                stack.append(value)
 
 
 def resolve_self_method_fqn(