Add encodings.mbcs and encodings.oem (#13122)

stdlib/@tests/stubtest_allowlists/darwin.txt

@@ -32,6 +32,8 @@ select.POLLMSG   # system dependent
 _winapi
 asyncio.windows_events
 asyncio.windows_utils
+encodings.oem
+encodings.mbcs
 msvcrt
 nt
 winreg

stdlib/@tests/stubtest_allowlists/linux.txt

@@ -13,6 +13,8 @@ selectors.KqueueSelector
 _winapi
 asyncio.windows_events
 asyncio.windows_utils
+encodings.oem
+encodings.mbcs
 msvcrt
 nt
 winreg

stdlib/@tests/stubtest_allowlists/win32.txt

@@ -4,8 +4,6 @@ ctypes.GetLastError  # Is actually a pointer
 multiprocessing.reduction.AbstractReducer.DupHandle
 
 # Exists at runtime, but missing from stubs
-encodings.mbcs
-encodings.oem
 _winapi.CreateFileMapping
 _winapi.MapViewOfFile
 _winapi.OpenFileMapping

stdlib/encodings/mbcs.pyi

@@ -0,0 +1,28 @@
+import codecs
+import sys
+from _typeshed import ReadableBuffer
+
+if sys.platform == "win32":
+    encode = codecs.mbcs_encode
+
+    def decode(input: ReadableBuffer, errors: str | None = "strict") -> tuple[str, int]: ...
+
+    class IncrementalEncoder(codecs.IncrementalEncoder):
+        def encode(self, input: str, final: bool = False) -> bytes: ...
+
+    class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
+        # At runtime, this is codecs.mbcs_decode
+        @staticmethod
+        def _buffer_decode(data: ReadableBuffer, errors: str | None = None, final: bool = False, /) -> tuple[str, int]: ...
+
+    class StreamWriter(codecs.StreamWriter):
+        # At runtime, this is codecs.mbcs_encode
+        @staticmethod
+        def encode(str: str, errors: str | None = None, /) -> tuple[bytes, int]: ...
+
+    class StreamReader(codecs.StreamReader):
+        # At runtime, this is codecs.mbcs_decode
+        @staticmethod
+        def decode(data: ReadableBuffer, errors: str | None = None, final: bool = False, /) -> tuple[str, int]: ...
+
+    def getregentry() -> codecs.CodecInfo: ...

stdlib/encodings/oem.pyi

@@ -0,0 +1,28 @@
+import codecs
+import sys
+from _typeshed import ReadableBuffer
+
+if sys.platform == "win32":
+    encode = codecs.oem_encode
+
+    def decode(input: ReadableBuffer, errors: str | None = "strict") -> tuple[str, int]: ...
+
+    class IncrementalEncoder(codecs.IncrementalEncoder):
+        def encode(self, input: str, final: bool = False) -> bytes: ...
+
+    class IncrementalDecoder(codecs.BufferedIncrementalDecoder):
+        # At runtime, this is codecs.oem_decode
+        @staticmethod
+        def _buffer_decode(data: ReadableBuffer, errors: str | None = None, final: bool = False, /) -> tuple[str, int]: ...
+
+    class StreamWriter(codecs.StreamWriter):
+        # At runtime, this is codecs.oem_encode
+        @staticmethod
+        def encode(str: str, errors: str | None = None, /) -> tuple[bytes, int]: ...
+
+    class StreamReader(codecs.StreamReader):
+        # At runtime, this is codecs.oem_decode
+        @staticmethod
+        def decode(data: ReadableBuffer, errors: str | None = None, final: bool = False, /) -> tuple[str, int]: ...
+
+    def getregentry() -> codecs.CodecInfo: ...