call toinstance() on type arguments passed to mapped_column()

Change-Id: I875cfbd925cb08e0a5235f87d13341d319c955bc

2 files changed, 5 insertions, 3 deletions

diff --git a/lib/sqlalchemy/sql/sqltypes.py b/lib/sqlalchemy/sql/sqltypes.py
index c67614070..de833cd89 100644
--- a/lib/sqlalchemy/sql/sqltypes.py
+++ b/lib/sqlalchemy/sql/sqltypes.py
@@ -46,7 +46,7 @@ from .elements import Slice
 from .elements import TypeCoerce as type_coerce  # noqa
 from .type_api import Emulated
 from .type_api import NativeForEmulated  # noqa
-from .type_api import to_instance
+from .type_api import to_instance as to_instance
 from .type_api import TypeDecorator as TypeDecorator
 from .type_api import TypeEngine as TypeEngine
 from .type_api import TypeEngineMixin
diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index 46bf151ea..efaf5d2a7 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -41,6 +41,7 @@ from ..util.typing import TypeGuard
 
 # these are back-assigned by sqltypes.
 if typing.TYPE_CHECKING:
+    from ._typing import _TypeEngineArgument
     from .elements import BindParameter
     from .elements import ColumnElement
     from .operators import OperatorType
@@ -55,7 +56,6 @@ if typing.TYPE_CHECKING:
     from .sqltypes import TABLEVALUE as TABLEVALUE  # noqa: F401
     from ..engine.interfaces import Dialect
 
-
 _T = TypeVar("_T", bound=Any)
 _T_co = TypeVar("_T_co", bound=Any, covariant=True)
 _T_con = TypeVar("_T_con", bound=Any, contravariant=True)
@@ -642,7 +642,9 @@ class TypeEngine(Visitable, Generic[_T]):
         raise NotImplementedError()
 
     def with_variant(
-        self: SelfTypeEngine, type_: TypeEngine[Any], *dialect_names: str
+        self: SelfTypeEngine,
+        type_: _TypeEngineArgument[Any],
+        *dialect_names: str,
     ) -> SelfTypeEngine:
         r"""Produce a copy of this type object that will utilize the given
         type when applied to the dialect of the given name.