1 files changed, 32 insertions, 6 deletions

diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index ca64296c1..93caa0ee5 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -20,6 +20,7 @@ import re
 import sys
 import textwrap
 import types
+import typing
 from typing import Any
 from typing import Callable
 from typing import Generic
@@ -31,10 +32,10 @@ import warnings
 
 from . import _collections
 from . import compat
+from . import typing as compat_typing
 from .. import exc
 
 _T = TypeVar("_T")
-_MP = TypeVar("_MP", bound="memoized_property[Any]")
 
 
 def md5_hex(x):
@@ -166,7 +167,13 @@ def map_bits(fn, n):
         n ^= b
 
 
-def decorator(target):
+_Fn = typing.TypeVar("_Fn", bound=typing.Callable)
+_Args = compat_typing.ParamSpec("_Args")
+
+
+def decorator(
+    target: typing.Callable[compat_typing.Concatenate[_Fn, _Args], typing.Any]
+) -> _Fn:
     """A signature-matching decorator factory."""
 
     def decorate(fn):
@@ -198,7 +205,7 @@ def %(name)s%(grouped_args)s:
         decorated.__wrapped__ = fn
         return update_wrapper(decorated, fn)
 
-    return update_wrapper(decorate, target)
+    return typing.cast(_Fn, update_wrapper(decorate, target))
 
 
 def _update_argspec_defaults_into_env(spec, env):
@@ -227,7 +234,16 @@ def _exec_code_in_env(code, env, fn_name):
     return env[fn_name]
 
 
-def public_factory(target, location, class_location=None):
+_TE = TypeVar("_TE")
+
+_P = compat_typing.ParamSpec("_P")
+
+
+def public_factory(
+    target: typing.Callable[_P, _TE],
+    location: str,
+    class_location: Optional[str] = None,
+) -> typing.Callable[_P, _TE]:
     """Produce a wrapping function for the given cls or classmethod.
 
     Rationale here is so that the __init__ method of the
@@ -273,6 +289,7 @@ def %(name)s%(grouped_args)s:
         "__name__": callable_.__module__,
     }
     exec(code, env)
+
     decorated = env[location_name]
 
     if hasattr(fn, "_linked_to"):
@@ -1077,6 +1094,11 @@ def as_interface(obj, cls=None, methods=None, required=None):
     )
 
 
+Selfmemoized_property = TypeVar(
+    "Selfmemoized_property", bound="memoized_property[Any]"
+)
+
+
 class memoized_property(Generic[_T]):
     """A read-only @property that is only evaluated once."""
 
@@ -1090,14 +1112,18 @@ class memoized_property(Generic[_T]):
         self.__name__ = fget.__name__
 
     @overload
-    def __get__(self: _MP, obj: None, cls: Any) -> _MP:
+    def __get__(
+        self: Selfmemoized_property, obj: None, cls: Any
+    ) -> Selfmemoized_property:
         ...
 
     @overload
     def __get__(self, obj: Any, cls: Any) -> _T:
         ...
 
-    def __get__(self: _MP, obj: Any, cls: Any) -> Union[_MP, _T]:
+    def __get__(
+        self: Selfmemoized_property, obj: Any, cls: Any
+    ) -> Union[Selfmemoized_property, _T]:
         if obj is None:
             return self
         obj.__dict__[self.__name__] = result = self.fget(obj)