iotests: annotate TestRunner.shared_self for mypy 2.4

mypy 2.4.0 infers the unannotated class attribute "shared_self = None" as having type "None" and rejects the later assignment of a TestRunner instance in run_tests_pool():

testrunner.py:126: error: Incompatible types in assignment (expression has type "TestRunner", variable has type "None")

Earlier mypy versions treated the attribute as a partial type and accepted the assignment. Give the attribute an explicit Optional['TestRunner'] annotation so both old and new mypy agree.

Fixes tests/linters.py::TestLinters::test_mypy_iotests with mypy >= 2.4.

---
CI run with mypy 2.4: https://gitlab.com/tpambor/qemu/-/pipelines/2905639361

---
 tests/qemu-iotests/testrunner.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index cc36867719..729680da4a 100644
@@ -108,7 +108,7 @@ def __init__(self, status: str, description: str = '',
 
 
 class TestRunner(contextlib.AbstractContextManager['TestRunner']):
-    shared_self = None
+    shared_self: Optional['TestRunner'] = None
 
     @staticmethod
     def proc_run_test(test: str, test_field_width: int) -> TestResult:

---
base-commit: f7ada39edacaa5c26b30e98b94017b0b2ccbcf94
change-id: 20261002-mypy-2-4-2544da3f4e17

Best regards,

Tim Pambor <[email protected]>

Am 02.10.2026 um 09:04 hat Tim Pambor geschrieben:

Thanks, applied to the block branch.

Kevin