general: move assert_never to my.core.compat as it's in stdlib from 3.11

rely on typing-extensions for fallback

introducing typing-extensions dependency without fallback, should be ok since it's in the top 10 of popular packages

my/core/__init__.py

@@ -4,7 +4,7 @@ from .common import Json
 from .common import warn_if_empty
 from .common import stat, Stats
 from .common import datetime_naive, datetime_aware
-from .common import assert_never
+from .compat import assert_never
 
 from .cfg import make_config
 from .error import Res, unwrap
@@ -26,7 +26,7 @@ __all__ = [
     'warn_if_empty',
     'stat', 'Stats',
     'datetime_aware', 'datetime_naive',
-    'assert_never',
+    'assert_never',  # TODO maybe deprecate from use in my.core? will be in stdlib soon
 
     'make_config',
 
@@ -34,7 +34,7 @@ __all__ = [
 
     'Res', 'unwrap',
 
-    'dataclass', 'Path',
+    'dataclass', 'Path',  # TODO deprecate these from use in my.core
 ]
 
 

my/core/common.py

@@ -27,7 +27,10 @@ from typing import (
     get_origin,
 )
 import warnings
+
 from . import warnings as core_warnings
+from . import compat
+from .compat import deprecated
 
 # some helper functions
 PathIsh = Union[Path, str]
@@ -633,11 +636,6 @@ class DummyExecutor(Executor):
         self._shutdown = True
 
 
-# see https://hakibenita.com/python-mypy-exhaustive-checking#exhaustiveness-checking
-def assert_never(value: NoReturn) -> NoReturn:
-    assert False, f'Unhandled value: {value} ({type(value).__name__})'
-
-
 def _check_all_hashable(fun):
     # TODO ok, take callable?
     hints = get_type_hints(fun)
@@ -693,6 +691,13 @@ def unique_everseen(
 
 
 ## legacy imports, keeping them here for backwards compatibility
+## hiding behind TYPE_CHECKING so it works in runtime
+## in principle, warnings.deprecated decorator should cooperate with mypy, but doesn't look like it works atm?
+## perhaps it doesn't work when it's used from typing_extensions
+if not TYPE_CHECKING:
+    assert_never = deprecated('use my.core.compat.assert_never instead')(compat.assert_never)
+
+# TODO wrap in deprecated decorator as well?
 from functools import cached_property as cproperty
 from typing import Literal
 from .cachew import mcachew

my/core/compat.py

@@ -121,3 +121,15 @@ if sys.version_info[:2] >= (3, 10):
     from types import NoneType
 else:
     NoneType = type(None)
+
+
+if sys.version_info[:2] >= (3, 13):
+    from warnings import deprecated
+else:
+    from typing_extensions import deprecated
+
+
+if sys.version_info[:2] >= (3, 11):
+    from typing import assert_never
+else:
+    from typing_extensions import assert_never

my/core/sqlite.py

@@ -9,7 +9,8 @@ from tempfile import TemporaryDirectory
 from typing import Tuple, Any, Iterator, Callable, Optional, Union, Literal
 
 
-from .common import PathIsh, assert_never
+from .common import PathIsh
+from .compat import assert_never
 
 
 def sqlite_connect_immutable(db: PathIsh) -> sqlite3.Connection: