Allow with_variant to take TypeEngine instance like Column. (#245)

Fixes Fixes: #244

Author: tapetersen

sqlalchemy-stubs/sql/type_api.pyi

@@ -96,7 +96,7 @@ class TypeEngine(Traversible, Generic[_T]):
     @property
     def python_type(self) -> Type[_T]: ...
     def with_variant(
-        self, type_: Type[TypeEngine[_U]], dialect_name: str
+        self, type_: Union[Type[TypeEngine[_U]], TypeEngine[_U]], dialect_name: str
     ) -> Variant[_U]: ...
     def as_generic(self, allow_nulltype: bool = ...) -> TypeEngine[Any]: ...
     def dialect_impl(self, dialect: Dialect) -> Type[Any]: ...
@@ -177,7 +177,7 @@ class Variant(TypeDecorator[_T]):
     ) -> Union[_VT, TypeEngine[Any]]: ...
     def load_dialect_impl(self, dialect: Dialect) -> TypeEngine[Any]: ...
     def with_variant(
-        self, type_: Type[TypeEngine[_U]], dialect_name: str
+        self, type_: Union[Type[TypeEngine[_U]], TypeEngine[_U]], dialect_name: str
     ) -> Variant[_U]: ...
     @property
     def comparator_factory(self) -> Type[Any]: ...  # type: ignore[override]

test/files/column_arguments2.py

@@ -80,3 +80,11 @@
 # These seems supported now
 Column(Integer, ForeignKey("a.id"), type_=String)
 Column("name", ForeignKey("a.id"), name="String")
+
+
+# TypeEngine.with_variant should accept both a TypeEngine instance and the Concrete Type
+Integer().with_variant(Integer, "mysql")
+Integer().with_variant(Integer(), "mysql")
+# Also test Variant.with_variant
+Integer().with_variant(Integer, "mysql").with_variant(Integer, "mysql")
+Integer().with_variant(Integer, "mysql").with_variant(Integer(), "mysql")