fix(used-before-assignment): resolve false negative for type_checking guard

Author: zenlyj

pylint/checkers/variables.py

@@ -1787,12 +1787,12 @@ def _check_consumer(
         if found_nodes is None:
             return (VariableVisitConsumerAction.CONTINUE, None)
         if not found_nodes:
-            self._report_unfound_name_definition(node, current_consumer)
+            is_reported = self._report_unfound_name_definition(node, current_consumer)
             # Mark for consumption any nodes added to consumed_uncertain by
             # get_next_to_consume() because they might not have executed.
             nodes_to_consume = current_consumer.consumed_uncertain[node.name]
             nodes_to_consume = self._filter_type_checking_import_from_consumption(
-                node, nodes_to_consume
+                node, nodes_to_consume, is_reported
             )
             return (
                 VariableVisitConsumerAction.RETURN,
@@ -1966,24 +1966,24 @@ def _report_unfound_name_definition(
         self,
         node: nodes.NodeNG,
         current_consumer: NamesConsumer,
-    ) -> None:
+    ) -> bool:
         """Reports used-before-assignment when all name definition nodes
         get filtered out by NamesConsumer.
         """
         if (
             self._postponed_evaluation_enabled
             and utils.is_node_in_type_annotation_context(node)
         ):
-            return
+            return False
         if self._is_builtin(node.name):
-            return
+            return False
         if self._is_variable_annotation_in_function(node):
-            return
+            return False
         if (
             node.name in self._evaluated_type_checking_scopes
             and node.scope() in self._evaluated_type_checking_scopes[node.name]
         ):
-            return
+            return False
 
         confidence = HIGH
         if node.name in current_consumer.names_under_always_false_test:
@@ -2003,10 +2003,13 @@ def _report_unfound_name_definition(
             confidence=confidence,
         )
 
+        return True
+
     def _filter_type_checking_import_from_consumption(
         self,
         node: nodes.NodeNG,
         nodes_to_consume: list[nodes.NodeNG],
+        is_reported: bool
     ) -> list[nodes.NodeNG]:
         """Do not consume type-checking import node as used-before-assignment
         may invoke in different scopes.
@@ -2022,7 +2025,7 @@ def _filter_type_checking_import_from_consumption(
         )
         # If used-before-assignment reported for usage of type checking import
         # keep track of its scope
-        if type_checking_import and not self._is_variable_annotation_in_function(node):
+        if type_checking_import and is_reported:
             self._evaluated_type_checking_scopes.setdefault(node.name, []).append(
                 node.scope()
             )

tests/functional/u/used/used_before_assignment_scoping.py

@@ -1,5 +1,6 @@
-# pylint: disable=missing-function-docstring, missing-module-docstring
+# pylint: disable=missing-function-docstring, missing-module-docstring, unused-variable, too-few-public-methods, no-member, missing-class-docstring
 
+from __future__ import annotations
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
@@ -16,3 +17,12 @@ def func():
     first = datetime.now()  # [used-before-assignment]
     second = datetime.now()
     return first, second
+
+
+def x() -> datetime.datetime:  # this is good
+    return datetime.datetime.now()  # [used-before-assignment]
+
+
+class Z:
+    def something(self) -> None:
+        z = datetime.datetime.now()  # [used-before-assignment]

tests/functional/u/used/used_before_assignment_scoping.txt

@@ -1,2 +1,4 @@
-used-before-assignment:10:13:10:21:func_two:Using variable 'datetime' before assignment:INFERENCE
-used-before-assignment:16:12:16:20:func:Using variable 'datetime' before assignment:INFERENCE
+used-before-assignment:11:13:11:21:func_two:Using variable 'datetime' before assignment:INFERENCE
+used-before-assignment:17:12:17:20:func:Using variable 'datetime' before assignment:INFERENCE
+used-before-assignment:23:11:23:19:x:Using variable 'datetime' before assignment:INFERENCE
+used-before-assignment:28:12:28:20:Z.something:Using variable 'datetime' before assignment:INFERENCE