Require build class parent (#2557)

* enforce a non-None parent in build_class

We also remove `add_local_node` to avoid redundancy. Instead we do the
   attachment to the parent scope in the constructor of `ClassDef`.

We append a node to the body of the frame when it is also the
   parent. If it's not a parent, then the node should belong to the
   "body" of the parent if it existed. An example is a definition
   within an "if", where the parent is the If node, but the frame is
   the whole module.

it's a part of the campaign to get rid of non-module roots

Author: temyurchenko

astroid/helpers.py

@@ -37,8 +37,7 @@ def safe_infer(
 
 
 def _build_proxy_class(cls_name: str, builtins: nodes.Module) -> nodes.ClassDef:
-    proxy = raw_building.build_class(cls_name)
-    proxy.parent = builtins
+    proxy = raw_building.build_class(cls_name, builtins)
     return proxy
 
 

astroid/nodes/scoped_nodes/scoped_nodes.py

@@ -178,6 +178,13 @@ def function_to_method(n, klass):
     return n
 
 
+def _attach_to_parent(node: NodeNG, name: str, parent: NodeNG):
+    frame = parent.frame()
+    frame.set_local(name, node)
+    if frame is parent:
+        frame._append_node(node)
+
+
 class Module(LocalsDictNodeNG):
     """Class representing an :class:`ast.Module` node.
 
@@ -1935,7 +1942,7 @@ def __init__(
             parent=parent,
         )
         if parent and not isinstance(parent, Unknown):
-            parent.frame().set_local(name, self)
+            _attach_to_parent(self, name, parent)
 
         for local_name, node in self.implicit_locals():
             self.add_local_node(node, local_name)

astroid/raw_building.py

@@ -49,15 +49,15 @@ def _attach_local_node(parent, node, name: str) -> None:
     parent.add_local_node(node)
 
 
-def _add_dunder_class(func, member) -> None:
+def _add_dunder_class(func, parent: nodes.NodeNG, member) -> None:
     """Add a __class__ member to the given func node, if we can determine it."""
     python_cls = member.__class__
     cls_name = getattr(python_cls, "__name__", None)
     if not cls_name:
         return
     cls_bases = [ancestor.__name__ for ancestor in python_cls.__bases__]
     doc = python_cls.__doc__ if isinstance(python_cls.__doc__, str) else None
-    ast_klass = build_class(cls_name, cls_bases, doc)
+    ast_klass = build_class(cls_name, parent, cls_bases, doc)
     func.instance_attrs["__class__"] = [ast_klass]
 
 
@@ -97,7 +97,10 @@ def build_module(name: str, doc: str | None = None) -> nodes.Module:
 
 
 def build_class(
-    name: str, basenames: Iterable[str] = (), doc: str | None = None
+    name: str,
+    parent: nodes.NodeNG,
+    basenames: Iterable[str] = (),
+    doc: str | None = None,
 ) -> nodes.ClassDef:
     """Create and initialize an astroid ClassDef node."""
     node = nodes.ClassDef(
@@ -106,7 +109,7 @@ def build_class(
         col_offset=0,
         end_lineno=0,
         end_col_offset=0,
-        parent=nodes.Unknown(),
+        parent=parent,
     )
     node.postinit(
         bases=[
@@ -343,7 +346,7 @@ def object_build_methoddescriptor(
         getattr(member, "__name__", None) or localname, doc=member.__doc__
     )
     node.add_local_node(func, localname)
-    _add_dunder_class(func, member)
+    _add_dunder_class(func, node, member)
 
 
 def _base_class_object_build(
@@ -359,9 +362,8 @@ def _base_class_object_build(
     class_name = name or getattr(member, "__name__", None) or localname
     assert isinstance(class_name, str)
     doc = member.__doc__ if isinstance(member.__doc__, str) else None
-    klass = build_class(class_name, basenames, doc)
+    klass = build_class(class_name, node, basenames, doc)
     klass._newstyle = isinstance(member, type)
-    node.add_local_node(klass, localname)
     try:
         # limit the instantiation trick since it's too dangerous
         # (such as infinite test execution...)
@@ -603,14 +605,11 @@ def _astroid_bootstrapping() -> None:
 
     for cls, node_cls in node_classes.CONST_CLS.items():
         if cls is TYPE_NONE:
-            proxy = build_class("NoneType")
-            proxy.parent = astroid_builtin
+            proxy = build_class("NoneType", astroid_builtin)
         elif cls is TYPE_NOTIMPLEMENTED:
-            proxy = build_class("NotImplementedType")
-            proxy.parent = astroid_builtin
+            proxy = build_class("NotImplementedType", astroid_builtin)
         elif cls is TYPE_ELLIPSIS:
-            proxy = build_class("Ellipsis")
-            proxy.parent = astroid_builtin
+            proxy = build_class("Ellipsis", astroid_builtin)
         else:
             proxy = astroid_builtin.getattr(cls.__name__)[0]
             assert isinstance(proxy, nodes.ClassDef)

tests/brain/test_brain.py

@@ -1705,7 +1705,8 @@ def test_infer_dict_from_keys() -> None:
     )
     for node in bad_nodes:
         with pytest.raises(InferenceError):
-            next(node.infer())
+            if isinstance(next(node.infer()), util.UninferableBase):
+                raise InferenceError
 
     # Test uninferable values
     good_nodes = astroid.extract_node(

tests/test_helpers.py

@@ -26,8 +26,7 @@ def _extract(self, obj_name: str) -> ClassDef:
         return self.builtins.getattr(obj_name)[0]
 
     def _build_custom_builtin(self, obj_name: str) -> ClassDef:
-        proxy = raw_building.build_class(obj_name)
-        proxy.parent = self.builtins
+        proxy = raw_building.build_class(obj_name, self.builtins)
         return proxy
 
     def assert_classes_equal(self, cls: ClassDef, other: ClassDef) -> None:

tests/test_raw_building.py

@@ -33,6 +33,8 @@
     build_module,
 )
 
+DUMMY_MOD = build_module("DUMMY")
+
 
 class RawBuildingTC(unittest.TestCase):
     def test_attach_dummy_node(self) -> None:
@@ -48,7 +50,7 @@ def test_build_module(self) -> None:
         self.assertEqual(node.parent, None)
 
     def test_build_class(self) -> None:
-        node = build_class("MyClass")
+        node = build_class("MyClass", DUMMY_MOD)
         self.assertEqual(node.name, "MyClass")
         self.assertEqual(node.doc_node, None)