remove errant NO_KEY symbol

the symbol from base is used in the event API and is
passed along from attributes here.

for the additional use where it's an exception case for
attribute name as passed by hybrid, use a different symbol name.

Change-Id: I8c5c0e71d19185ebec64f2fcbfe1e9be74e54287

1 files changed, 9 insertions, 7 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 5e6852cbf..65d6970a9 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -55,6 +55,7 @@ from .base import Mapped as Mapped  # noqa
 from .base import NEVER_SET  # noqa
 from .base import NO_AUTOFLUSH
 from .base import NO_CHANGE  # noqa
+from .base import NO_KEY
 from .base import NO_RAISE
 from .base import NO_VALUE
 from .base import NON_PERSISTENT_OK  # noqa
@@ -115,20 +116,16 @@ if TYPE_CHECKING:
 _T = TypeVar("_T")
 
 
-class NoKey(str):
-    pass
-
-
 _AllPendingType = Sequence[
     Tuple[Optional["InstanceState[Any]"], Optional[object]]
 ]
 
-NO_KEY = NoKey("no name")
-
 SelfQueryableAttribute = TypeVar(
     "SelfQueryableAttribute", bound="QueryableAttribute[Any]"
 )
 
+_UNKNOWN_ATTR_KEY = object()
+
 
 @inspection._self_inspects
 class QueryableAttribute(
@@ -327,7 +324,12 @@ class QueryableAttribute(
     def _memoized_attr_expression(self) -> ColumnElement[_T]:
         annotations: _AnnotationDict
 
-        if self.key is NO_KEY:
+        # applies only to Proxy() as used by hybrid.
+        # currently is an exception to typing rather than feeding through
+        # non-string keys.
+        # ideally Proxy() would have a separate set of methods to deal
+        # with this case.
+        if self.key is _UNKNOWN_ATTR_KEY:  # type: ignore[comparison-overlap]
             annotations = {"entity_namespace": self._entity_namespace}
         else:
             annotations = {