codecs: various fixes (#4526)

Co-authored-by: hauntsaninja <>

stdlib/2and3/codecs.pyi

@@ -81,7 +81,7 @@ def decode(obj: bytes, encoding: _BytesToBytesEncodingT, errors: str = ...) -> b
 def decode(obj: str, encoding: Literal["rot13", "rot_13"] = ..., errors: str = ...) -> Text: ...
 @overload
 def decode(obj: _Encoded, encoding: str = ..., errors: str = ...) -> _Decoded: ...
-def lookup(encoding: str) -> CodecInfo: ...
+def lookup(__encoding: str) -> CodecInfo: ...
 def utf_16_be_decode(__obj: _Encoded, __errors: str = ..., __final: bool = ...) -> Tuple[_Decoded, int]: ...  # undocumented
 def utf_16_be_encode(__obj: _Decoded, __errors: str = ...) -> Tuple[_Encoded, int]: ...  # undocumented
 
@@ -99,16 +99,18 @@ class CodecInfo(Tuple[_Encoder, _Decoder, _StreamReader, _StreamWriter]):
     @property
     def incrementaldecoder(self) -> _IncrementalDecoder: ...
     name: str
-    def __init__(
+    def __new__(
         self,
         encode: _Encoder,
         decode: _Decoder,
-        streamreader: _StreamReader = ...,
-        streamwriter: _StreamWriter = ...,
-        incrementalencoder: _IncrementalEncoder = ...,
-        incrementaldecoder: _IncrementalDecoder = ...,
-        name: str = ...,
-    ) -> None: ...
+        streamreader: Optional[_StreamReader] = ...,
+        streamwriter: Optional[_StreamWriter] = ...,
+        incrementalencoder: Optional[_IncrementalEncoder] = ...,
+        incrementaldecoder: Optional[_IncrementalDecoder] = ...,
+        name: Optional[str] = ...,
+        *,
+        _is_text_encoding: Optional[bool] = ...,
+    ) -> CodecInfo: ...
 
 def getencoder(encoding: str) -> _Encoder: ...
 def getdecoder(encoding: str) -> _Decoder: ...
@@ -116,9 +118,13 @@ def getincrementalencoder(encoding: str) -> _IncrementalEncoder: ...
 def getincrementaldecoder(encoding: str) -> _IncrementalDecoder: ...
 def getreader(encoding: str) -> _StreamReader: ...
 def getwriter(encoding: str) -> _StreamWriter: ...
-def register(search_function: Callable[[str], Optional[CodecInfo]]) -> None: ...
-def open(filename: str, mode: str = ..., encoding: str = ..., errors: str = ..., buffering: int = ...) -> StreamReaderWriter: ...
-def EncodedFile(file: IO[_Encoded], data_encoding: str, file_encoding: str = ..., errors: str = ...) -> StreamRecoder: ...
+def register(__search_function: Callable[[str], Optional[CodecInfo]]) -> None: ...
+def open(
+    filename: str, mode: str = ..., encoding: Optional[str] = ..., errors: str = ..., buffering: int = ...
+) -> StreamReaderWriter: ...
+def EncodedFile(
+    file: IO[_Encoded], data_encoding: str, file_encoding: Optional[str] = ..., errors: str = ...
+) -> StreamRecoder: ...
 def iterencode(iterator: Iterable[_Decoded], encoding: str, errors: str = ...) -> Generator[_Encoded, None, None]: ...
 def iterdecode(iterator: Iterable[_Encoded], encoding: str, errors: str = ...) -> Generator[_Decoded, None, None]: ...
 
@@ -136,8 +142,8 @@ BOM_UTF32_LE: bytes
 # It is expected that different actions be taken depending on which of the
 # three subclasses of `UnicodeError` is actually ...ed. However, the Union
 # is still needed for at least one of the cases.
-def register_error(name: str, error_handler: Callable[[UnicodeError], Tuple[Union[str, bytes], int]]) -> None: ...
-def lookup_error(name: str) -> Callable[[UnicodeError], Tuple[Union[str, bytes], int]]: ...
+def register_error(__errors: str, __handler: Callable[[UnicodeError], Tuple[Union[str, bytes], int]]) -> None: ...
+def lookup_error(__name: str) -> Callable[[UnicodeError], Tuple[Union[str, bytes], int]]: ...
 def strict_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
 def replace_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
 def ignore_errors(exception: UnicodeError) -> Tuple[Union[str, bytes], int]: ...
@@ -164,7 +170,7 @@ class IncrementalDecoder:
     errors: str
     def __init__(self, errors: str = ...) -> None: ...
     @abstractmethod
-    def decode(self, object: _Encoded, final: bool = ...) -> _Decoded: ...
+    def decode(self, input: _Encoded, final: bool = ...) -> _Decoded: ...
     def reset(self) -> None: ...
     def getstate(self) -> Tuple[_Encoded, int]: ...
     def setstate(self, state: Tuple[_Encoded, int]) -> None: ...