move OpenTextMode and friends to _typeshed (#4213)

stdlib/3/io.pyi

@@ -7,11 +7,6 @@ import sys
 from mmap import mmap
 from types import TracebackType
 
-if sys.version_info >= (3, 8):
-    from typing import Literal
-else:
-    from typing_extensions import Literal
-
 _bytearray_like = Union[bytearray, mmap]
 
 DEFAULT_BUFFER_SIZE: int
@@ -22,30 +17,6 @@ SEEK_END: int
 
 _T = TypeVar('_T', bound=IOBase)
 
-_OpenTextMode = Literal[
-    'r', 'r+', '+r', 'rt', 'tr', 'rt+', 'r+t', '+rt', 'tr+', 't+r', '+tr',
-    'w', 'w+', '+w', 'wt', 'tw', 'wt+', 'w+t', '+wt', 'tw+', 't+w', '+tw',
-    'a', 'a+', '+a', 'at', 'ta', 'at+', 'a+t', '+at', 'ta+', 't+a', '+ta',
-    'x', 'x+', '+x', 'xt', 'tx', 'xt+', 'x+t', '+xt', 'tx+', 't+x', '+tx',
-    'U', 'rU', 'Ur', 'rtU', 'rUt', 'Urt', 'trU', 'tUr', 'Utr',
-]
-_OpenBinaryModeUpdating = Literal[
-    'rb+', 'r+b', '+rb', 'br+', 'b+r', '+br',
-    'wb+', 'w+b', '+wb', 'bw+', 'b+w', '+bw',
-    'ab+', 'a+b', '+ab', 'ba+', 'b+a', '+ba',
-    'xb+', 'x+b', '+xb', 'bx+', 'b+x', '+bx',
-]
-_OpenBinaryModeWriting = Literal[
-    'wb', 'bw',
-    'ab', 'ba',
-    'xb', 'bx',
-]
-_OpenBinaryModeReading = Literal[
-    'rb', 'br',
-    'rbU', 'rUb', 'Urb', 'brU', 'bUr', 'Ubr',
-]
-_OpenBinaryMode = Union[_OpenBinaryModeUpdating, _OpenBinaryModeReading, _OpenBinaryModeWriting]
-
 open = builtins.open
 
 if sys.version_info >= (3, 8):

stdlib/3/pathlib.pyi

@@ -1,4 +1,4 @@
-from io import _OpenBinaryMode, _OpenTextMode
+from _typeshed import OpenBinaryMode, OpenTextMode
 from typing import (Any, BinaryIO, Generator, IO, List, Optional, Sequence,
                     TextIO, Tuple, Type, TypeVar, Union, overload)
 from types import TracebackType
@@ -100,10 +100,10 @@ class Path(PurePath):
         def mkdir(self, mode: int = ..., parents: bool = ...,
                   exist_ok: bool = ...) -> None: ...
     @overload
-    def open(self, mode: _OpenTextMode = ..., buffering: int = ..., encoding: Optional[str] = ..., errors: Optional[str] = ...,
+    def open(self, mode: OpenTextMode = ..., buffering: int = ..., encoding: Optional[str] = ..., errors: Optional[str] = ...,
              newline: Optional[str] = ...) -> TextIO: ...
     @overload
-    def open(self, mode: _OpenBinaryMode, buffering: int = ..., encoding: None = ..., errors: None = ...,
+    def open(self, mode: OpenBinaryMode, buffering: int = ..., encoding: None = ..., errors: None = ...,
              newline: None = ...) -> BinaryIO: ...
     @overload
     def open(self, mode: str, buffering: int = ..., encoding: Optional[str] = ..., errors: Optional[str] = ...,