use read-only Mapping for values dictionary type

Improved typing for the mapping passed to :meth:`.UpdateBase.values` to be
more open-ended about collection type, by indicating read-only ``Mapping``
instead of writeable ``Dict``, the latter of which would error out under
typing tools on too limited of a key type.

Fixes: #9376
Change-Id: Ib7fdbba05ca7e1082409e1b5616e6a010262f032

2 files changed, 6 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/_typing.py b/lib/sqlalchemy/sql/_typing.py
index 6bf9a5a1f..a828d6a0f 100644
--- a/lib/sqlalchemy/sql/_typing.py
+++ b/lib/sqlalchemy/sql/_typing.py
@@ -11,6 +11,7 @@ import operator
 from typing import Any
 from typing import Callable
 from typing import Dict
+from typing import Mapping
 from typing import Set
 from typing import Tuple
 from typing import Type
@@ -238,6 +239,9 @@ the DMLColumnRole to be able to accommodate.
 
 """
 
+_DMLKey = TypeVar("_DMLKey", bound=_DMLColumnArgument)
+_DMLColumnKeyMapping = Mapping[_DMLKey, Any]
+
 
 _DDLColumnArgument = Union[str, "Column[Any]", roles.DDLConstraintColumnRole]
 """DDL column.
diff --git a/lib/sqlalchemy/sql/dml.py b/lib/sqlalchemy/sql/dml.py
index 9042fdff7..dbbf09f1b 100644
--- a/lib/sqlalchemy/sql/dml.py
+++ b/lib/sqlalchemy/sql/dml.py
@@ -72,6 +72,7 @@ if TYPE_CHECKING:
     from ._typing import _ColumnExpressionArgument
     from ._typing import _ColumnsClauseArgument
     from ._typing import _DMLColumnArgument
+    from ._typing import _DMLColumnKeyMapping
     from ._typing import _DMLTableArgument
     from ._typing import _T0  # noqa
     from ._typing import _T1  # noqa
@@ -944,7 +945,7 @@ class ValuesBase(UpdateBase):
     def values(
         self,
         *args: Union[
-            Dict[_DMLColumnArgument, Any],
+            _DMLColumnKeyMapping[Any],
             Sequence[Any],
         ],
         **kwargs: Any,