Finalisation + extend tox typing to include all platforms.

src/click/_compat.py

@@ -10,8 +10,8 @@
 from types import TracebackType
 from weakref import WeakKeyDictionary
 
-CYGWIN = sys.platform == "cygwin"
-WIN = sys.platform == "win32"
+CYGWIN = sys.platform.startswith("cygwin")
+WIN = sys.platform.startswith("win")
 auto_wrap_for_ansi: t.Callable[[t.TextIO], t.TextIO] | None = None
 _ansi_re = re.compile(r"\033\[[;?0-9]*[a-zA-Z]")
 

src/click/_termui_impl.py

@@ -711,12 +711,11 @@ def getchar(echo: bool) -> str:
         #
         # Anyway, Click doesn't claim to do this Right(tm), and using `getwch`
         # is doing the right thing in more situations than with `getch`.
-        func: t.Callable[[], str]
 
         if echo:
-            func = msvcrt.getwche
+            func = t.cast(t.Callable[[], str], msvcrt.getwche)
         else:
-            func = msvcrt.getwch
+            func = t.cast(t.Callable[[], str], msvcrt.getwch)
 
         rv = func()
 

src/click/_winconsole.py

@@ -70,6 +70,8 @@
 
 if t.TYPE_CHECKING:
     try:
+        # Using `typing_extensions.Buffer` instead of `collections.abc`
+        # on Windows for some reason does not have `Sized` implemented.
         from collections.abc import Buffer  # type: ignore
     except ImportError:
         from typing_extensions import Buffer

tox.ini

@@ -23,9 +23,15 @@ commands = pre-commit run --all-files
 [testenv:typing]
 deps = -r requirements/typing.txt
 commands =
-    mypy
-    pyright tests/typing
-    pyright --verifytypes click --ignoreexternal
+    mypy --platform linux
+    mypy --platform darwin
+    mypy --platform win32
+    pyright tests/typing --pythonplatform Linux
+    pyright tests/typing --pythonplatform Darwin
+    pyright tests/typing --pythonplatform Windows
+    pyright --verifytypes click --ignoreexternal --pythonplatform Linux
+    pyright --verifytypes click --ignoreexternal --pythonplatform Darwin
+    pyright --verifytypes click --ignoreexternal --pythonplatform Windows
 
 [testenv:docs]
 deps = -r requirements/docs.txt