Prevent false positive undefined-variable for user-specified builtins given type annotations

ChangeLog

@@ -220,6 +220,11 @@ Release date: TBA
   Closes #5815
   Closes #5406
 
+* Fixed a false positive for ``unused-variable`` when a builtin specified in
+  ``--additional-builtins`` is given a type annotation.
+
+  Closes #6388
+
 * Fixed an ``AstroidError`` in 2.13.0 raised by the ``duplicate-code`` checker with
   ``ignore-imports`` or ``ignore-signatures`` enabled.
 

doc/whatsnew/2.13.rst

@@ -592,6 +592,11 @@ Other Changes
 
   Closes #5394
 
+* Fixed a false positive for ``unused-variable`` when a builtin specified in
+  ``--additional-builtins`` is given a type annotation.
+
+  Closes #6388
+
 * Fix false positive for 'nonexistent-operator' when repeated '-' are
   separated (e.g. by parens).
 

pylint/checkers/variables.py

@@ -2059,12 +2059,18 @@ def _maybe_used_and_assigned_at_once(defstmt: nodes.Statement) -> bool:
             or any(isinstance(arg, nodes.IfExp) for arg in value.args)
         )
 
-    @staticmethod
-    def _is_only_type_assignment(node: nodes.Name, defstmt: nodes.Statement) -> bool:
+    def _is_only_type_assignment(
+        self, node: nodes.Name, defstmt: nodes.Statement
+    ) -> bool:
         """Check if variable only gets assigned a type and never a value."""
         if not isinstance(defstmt, nodes.AnnAssign) or defstmt.value:
             return False
 
+        if node.name in self.linter.config.additional_builtins or utils.is_builtin(
+            node.name
+        ):
+            return False
+
         defstmt_frame = defstmt.frame(future=True)
         node_frame = node.frame(future=True)
 

tests/functional/u/undefined/undefined_variable_typing.py

@@ -4,9 +4,24 @@
 # Ensure attribute lookups in type comments are accounted for.
 # Reported in https://github.com/PyCQA/pylint/issues/4603
 
+from typing import TYPE_CHECKING, Any, Dict
+
 import foo
 from foo import Bar, Boo
 
 a = ...  # type: foo.Bar
 b = ...  # type: foo.Bar[Boo]
 c = ...  # type: Bar.Boo
+
+
+if TYPE_CHECKING:
+    __additional_builtin__: Dict[str, Any]
+    # For why this would emit redefined-builtin: https://github.com/PyCQA/pylint/pull/3643
+    # pylint: disable-next=redefined-builtin
+    repr: Any
+
+
+def run():
+    """https://github.com/PyCQA/pylint/issues/6388"""
+    print(repr)
+    return __additional_builtin__["test"]

tests/functional/u/undefined/undefined_variable_typing.rc

@@ -1,2 +1,4 @@
 [testoptions]
 except_implementations=PyPy
+[VARIABLES]
+additional-builtins=__additional_builtin__