Merge pull request #3602 from harupy/enable-warn-redundant-casts

Enable `warn_redundant_casts` for `mypy`

optuna/storages/_in_memory.py

@@ -2,7 +2,6 @@
 from datetime import datetime
 import threading
 from typing import Any
-from typing import cast
 from typing import Container
 from typing import Dict
 from typing import Iterator
@@ -166,7 +165,7 @@ def _build_study_summary(self, study_id: int, include_best_trial: bool = True) -
             n_trials=len(study.trials),
             datetime_start=min(
                 [
-                    cast(datetime, trial.datetime_start)
+                    trial.datetime_start
                     for trial in self.get_all_trials(study_id, deepcopy=False)
                     if trial.datetime_start is not None
                 ],

optuna/storages/_redis.py

@@ -390,7 +390,7 @@ def _create_new_trial(
             study_summary.n_trials = len(self._get_study_trials(study_id))
             min_datetime_start = min(
                 [
-                    cast(datetime, t.datetime_start)
+                    t.datetime_start
                     for t in self.get_all_trials(study_id)
                     if t.datetime_start is not None
                 ],

setup.cfg

@@ -15,4 +15,5 @@ exclude = venv,build,tutorial,.tox,.asv
 disallow_untyped_defs = True
 ignore_missing_imports = True
 no_implicit_optional = True
+warn_redundant_casts = True
 exclude = venv|build|docs|tutorial|optuna/storages/_rdb/alembic