Fix FunctionDef isinstance checks (#8607)

Author: cdce8p

pylint/checkers/typecheck.py

@@ -733,7 +733,9 @@ def _no_context_variadic(
         else:
             inferred_statement = inferred.statement(future=True)
 
-        if not length and isinstance(inferred_statement, nodes.Lambda):
+        if not length and isinstance(
+            inferred_statement, (nodes.Lambda, nodes.FunctionDef)
+        ):
             is_in_starred_context = _has_parent_of_type(node, variadic_type, statement)
             used_as_starred_argument = any(
                 variadic.value == name or variadic.value.parent_of(name)

pylint/checkers/utils.py

@@ -356,9 +356,10 @@ def is_defined_before(var_node: nodes.Name) -> bool:
         if defnode is None:
             continue
         defnode_scope = defnode.scope()
-        if isinstance(defnode_scope, (*COMP_NODE_TYPES, nodes.Lambda)):
+        if isinstance(
+            defnode_scope, (*COMP_NODE_TYPES, nodes.Lambda, nodes.FunctionDef)
+        ):
             # Avoid the case where var_node_scope is a nested function
-            # FunctionDef is a Lambda until https://github.com/pylint-dev/astroid/issues/291
             if isinstance(defnode_scope, nodes.FunctionDef):
                 var_node_scope = var_node.scope()
                 if var_node_scope is not defnode_scope and isinstance(

pylint/checkers/variables.py

@@ -2497,10 +2497,7 @@ def _loopvar_name(self, node: astroid.Name) -> None:
         # the usage is safe because the function will not be defined either if
         # the variable is not defined.
         scope = node.scope()
-        # FunctionDef subclasses Lambda due to a curious ontology. Check both.
-        # See https://github.com/pylint-dev/astroid/issues/291
-        # TODO: Revisit when astroid 3.0 includes the change
-        if isinstance(scope, nodes.Lambda) and any(
+        if isinstance(scope, (nodes.Lambda, nodes.FunctionDef)) and any(
             asmt.scope().parent_of(scope) for asmt in astmts
         ):
             return