pytype: stop excluding mercurial/ui.py ui.extractchoices() is perhaps making assumptions that it shouldn't about the pattern always matching, but presumably we have test coverage for that. PyCharm flags the updated classes with a warning "Class xxx must implement all abstract methods", and suggests adding `abc.ABC` to the superclasses. I'm not sure why, unless it doesn't recognize the `__getattr__()` delegation pattern. Additionally, we can't unconditionally subclass `typing.BinaryIO` because that defeats the `__getattr__` delegation to the wrapped object at runtime. Instead, it has to only subclass during the type checking phase[1]. In any event, this fixes: File "/mnt/c/Users/Matt/hg/mercurial/ui.py", line 1518, in _runpager: Function subprocess.Popen.__new__ was called with the wrong arguments [wrong-arg-types] Expected: (cls, args, bufsize, executable, stdin, stdout: Optional[Union[IO, int]] = ..., ...) Actually passed: (cls, args, bufsize, stdin, stdout: Union[mercurial.utils.procutil.WriteAllWrapper, mercurial.windows.winstdout], ...) File "/mnt/c/Users/Matt/hg/mercurial/ui.py", line 1798, in extractchoices: No attribute 'group' on None [attribute-error] In Optional[Match[bytes]] File "/mnt/c/Users/Matt/hg/mercurial/ui.py", line 1799, in extractchoices: No attribute 'group' on None [attribute-error] In Optional[Match[bytes]] [1] https://stackoverflow.com/q/71365594

--- a/mercurial/windows.py	Wed Dec 07 20:12:23 2022 +0100
+++ b/mercurial/windows.py	Fri Nov 25 18:39:47 2022 -0500
@@ -16,6 +16,10 @@
 import sys
 import winreg  # pytype: disable=import-error
 
+from typing import (
+    BinaryIO,
+)
+
 from .i18n import _
 from .pycompat import getattr
 from . import (
@@ -23,6 +27,7 @@
     error,
     policy,
     pycompat,
+    typelib,
     win32,
 )
 
@@ -208,7 +213,7 @@
     return encoding.unitolocal(pw)
 
 
-class winstdout:
+class winstdout(typelib.BinaryIO_Proxy):
     """Some files on Windows misbehave.
 
     When writing to a broken pipe, EINVAL instead of EPIPE may be raised.
@@ -217,7 +222,7 @@
     error may happen. Python 3 already works around that.
     """
 
-    def __init__(self, fp):
+    def __init__(self, fp: BinaryIO):
         self.fp = fp
 
     def __getattr__(self, key):