Fix frame() error on inferred node (#1263)

Co-authored-by: Pierre Sassoulas <[email protected]>

ChangeLog

@@ -12,6 +12,10 @@ What's New in astroid 2.9.1?
 ============================
 Release date: TBA
 
+* ``NodeNG.frame()`` and ``NodeNG.statement()`` will start raising ``ParentMissingError``
+  instead of ``AttributeError`` in astroid 3.0. This behaviour can already be triggered
+  by passing ``future=True`` to a ``frame()`` or ``statement()`` call.
+
 * Prefer the module loader get_source() method in AstroidBuilder's
   module_build() when possible to avoid assumptions about source
   code being available on a filesystem.  Otherwise the source cannot

astroid/nodes/node_classes.py

@@ -65,6 +65,7 @@
     from typing_extensions import Literal
 
 if TYPE_CHECKING:
+    from astroid import nodes
     from astroid.nodes import LocalsDictNodeNG
 
 
@@ -4795,7 +4796,9 @@ def postinit(self, target: NodeNG, value: NodeNG) -> None:
     See astroid/protocols.py for actual implementation.
     """
 
-    def frame(self):
+    def frame(
+        self, *, future: Literal[None, True] = None
+    ) -> Union["nodes.FunctionDef", "nodes.Module", "nodes.ClassDef", "nodes.Lambda"]:
         """The first parent frame node.
 
         A frame node is a :class:`Module`, :class:`FunctionDef`,

astroid/nodes/node_ng.py

@@ -314,7 +314,7 @@ def statement(
         return self.parent.statement(future=future)
 
     def frame(
-        self,
+        self, *, future: Literal[None, True] = None
     ) -> Union["nodes.FunctionDef", "nodes.Module", "nodes.ClassDef", "nodes.Lambda"]:
         """The first parent frame node.
 
@@ -323,7 +323,19 @@ def frame(
 
         :returns: The first parent frame node.
         """
-        return self.parent.frame()
+        if self.parent is None:
+            if future:
+                raise ParentMissingError(target=self)
+            warnings.warn(
+                "In astroid 3.0.0 NodeNG.frame() will return either a Frame node, "
+                "or raise ParentMissingError. AttributeError will no longer be raised. "
+                "This behaviour can already be triggered "
+                "by passing 'future=True' to a frame() call.",
+                DeprecationWarning,
+            )
+            raise AttributeError(f"{self} object has no attribute 'parent'")
+
+        return self.parent.frame(future=future)
 
     def scope(self) -> "nodes.LocalsDictNodeNG":
         """The first parent node defining a new scope.

astroid/nodes/scoped_nodes/scoped_nodes.py

@@ -859,7 +859,7 @@ def bool_value(self, context=None):
     def get_children(self):
         yield from self.body
 
-    def frame(self: T) -> T:
+    def frame(self: T, *, future: Literal[None, True] = None) -> T:
         """The node's frame node.
 
         A frame node is a :class:`Module`, :class:`FunctionDef`,
@@ -1474,7 +1474,7 @@ def get_children(self):
         yield self.args
         yield self.body
 
-    def frame(self: T) -> T:
+    def frame(self: T, *, future: Literal[None, True] = None) -> T:
         """The node's frame node.
 
         A frame node is a :class:`Module`, :class:`FunctionDef`,
@@ -2004,7 +2004,7 @@ def scope_lookup(self, node, name, offset=0):
                 return self, [frame]
         return super().scope_lookup(node, name, offset)
 
-    def frame(self: T) -> T:
+    def frame(self: T, *, future: Literal[None, True] = None) -> T:
         """The node's frame node.
 
         A frame node is a :class:`Module`, :class:`FunctionDef`,
@@ -3251,7 +3251,7 @@ def _get_assign_nodes(self):
         )
         return list(itertools.chain.from_iterable(children_assign_nodes))
 
-    def frame(self: T) -> T:
+    def frame(self: T, *, future: Literal[None, True] = None) -> T:
         """The node's frame node.
 
         A frame node is a :class:`Module`, :class:`FunctionDef`,

tests/unittest_nodes.py

@@ -55,6 +55,7 @@
     AstroidBuildingError,
     AstroidSyntaxError,
     AttributeInferenceError,
+    ParentMissingError,
     StatementMissing,
 )
 from astroid.nodes.node_classes import (
@@ -641,6 +642,13 @@ def _test(self, value: Any) -> None:
         with self.assertRaises(StatementMissing):
             node.statement(future=True)
 
+        with self.assertRaises(AttributeError):
+            with pytest.warns(DeprecationWarning) as records:
+                node.frame()
+                assert len(records) == 1
+        with self.assertRaises(ParentMissingError):
+            node.frame(future=True)
+
     def test_none(self) -> None:
         self._test(None)