stubgen: add import for types in __exit__ method signature (#19120)

Fixes #17037

Add import for `types` in `__exit__` method signature

Author: makridenko

mypy/stubgen.py

@@ -633,6 +633,11 @@ def _get_func_args(self, o: FuncDef, ctx: FunctionContext) -> list[ArgSig]:
             new_args = infer_method_arg_types(
                 ctx.name, ctx.class_info.self_var, [arg.name for arg in args]
             )
+
+            if ctx.name == "__exit__":
+                self.import_tracker.add_import("types")
+                self.import_tracker.require_name("types")
+
             if new_args is not None:
                 args = new_args
 

test-data/unit/stubgen.test

@@ -3777,6 +3777,8 @@ class MatchNames:
     def __exit__(self, type, value, traceback): ...
 
 [out]
+import types
+
 class MismatchNames:
     def __exit__(self, tp: type[BaseException] | None, val: BaseException | None, tb: types.TracebackType | None) -> None: ...