Add defaultdict.__(r)or__; improve ChainMap.__(r)or__ and UserDict.__(r)or__ (#10427)

Add __or__ to defaultdict

Also, add overloads with Self type to other __[r]or__ methods.

Author: eltoder

stdlib/builtins.pyi

@@ -1102,7 +1102,13 @@ class dict(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     __hash__: ClassVar[None]  # type: ignore[assignment]
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, __item: Any) -> GenericAlias: ...
+        @overload
+        def __or__(self, __value: Mapping[_KT, _VT]) -> dict[_KT, _VT]: ...
+        @overload
         def __or__(self, __value: Mapping[_T1, _T2]) -> dict[_KT | _T1, _VT | _T2]: ...
+        @overload
+        def __ror__(self, __value: Mapping[_KT, _VT]) -> dict[_KT, _VT]: ...
+        @overload
         def __ror__(self, __value: Mapping[_T1, _T2]) -> dict[_KT | _T1, _VT | _T2]: ...
         # dict.__ior__ should be kept roughly in line with MutableMapping.update()
         @overload  # type: ignore[misc]

stdlib/collections/__init__.pyi

@@ -83,8 +83,14 @@ class UserDict(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     @overload
     def fromkeys(cls, iterable: Iterable[_T], value: _S) -> UserDict[_T, _S]: ...
     if sys.version_info >= (3, 9):
+        @overload
+        def __or__(self, other: UserDict[_KT, _VT] | dict[_KT, _VT]) -> Self: ...
+        @overload
         def __or__(self, other: UserDict[_T1, _T2] | dict[_T1, _T2]) -> UserDict[_KT | _T1, _VT | _T2]: ...
-        def __ror__(self, other: UserDict[_T1, _T2] | dict[_T1, _T2]) -> UserDict[_KT | _T1, _VT | _T2]: ...  # type: ignore[misc]
+        @overload  # type: ignore[misc]
+        def __ror__(self, other: UserDict[_KT, _VT] | dict[_KT, _VT]) -> Self: ...
+        @overload  # type: ignore[misc]
+        def __ror__(self, other: UserDict[_T1, _T2] | dict[_T1, _T2]) -> UserDict[_KT | _T1, _VT | _T2]: ...
         # UserDict.__ior__ should be kept roughly in line with MutableMapping.update()
         @overload  # type: ignore[misc]
         def __ior__(self, other: SupportsKeysAndGetItem[_KT, _VT]) -> Self: ...
@@ -391,6 +397,15 @@ class defaultdict(dict[_KT, _VT], Generic[_KT, _VT]):
     def __missing__(self, __key: _KT) -> _VT: ...
     def __copy__(self) -> Self: ...
     def copy(self) -> Self: ...
+    if sys.version_info >= (3, 9):
+        @overload
+        def __or__(self, __value: Mapping[_KT, _VT]) -> Self: ...
+        @overload
+        def __or__(self, __value: Mapping[_T1, _T2]) -> defaultdict[_KT | _T1, _VT | _T2]: ...
+        @overload
+        def __ror__(self, __value: Mapping[_KT, _VT]) -> Self: ...
+        @overload
+        def __ror__(self, __value: Mapping[_T1, _T2]) -> defaultdict[_KT | _T1, _VT | _T2]: ...
 
 class ChainMap(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     maps: list[MutableMapping[_KT, _VT]]
@@ -425,7 +440,13 @@ class ChainMap(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
     @overload
     def fromkeys(cls, __iterable: Iterable[_T], __value: _S) -> ChainMap[_T, _S]: ...
     if sys.version_info >= (3, 9):
+        @overload
+        def __or__(self, other: Mapping[_KT, _VT]) -> Self: ...
+        @overload
         def __or__(self, other: Mapping[_T1, _T2]) -> ChainMap[_KT | _T1, _VT | _T2]: ...
+        @overload
+        def __ror__(self, other: Mapping[_KT, _VT]) -> Self: ...
+        @overload
         def __ror__(self, other: Mapping[_T1, _T2]) -> ChainMap[_KT | _T1, _VT | _T2]: ...
         # ChainMap.__ior__ should be kept roughly in line with MutableMapping.update()
         @overload  # type: ignore[misc]