gh-60580: Fix a wrong type of ctypes.wintypes.BYTE

Lib/ctypes/wintypes.py

@@ -1,7 +1,7 @@
 # The most useful windows datatypes
 import ctypes
 
-BYTE = ctypes.c_byte
+BYTE = ctypes.c_ubyte
 WORD = ctypes.c_ushort
 DWORD = ctypes.c_ulong
 

Lib/test/test_ctypes/test_wintypes.py

@@ -1,3 +1,6 @@
+# See <https://learn.microsoft.com/en-us/windows/win32/winprog/windows-data-types>
+# for reference.
+
 import unittest
 
 # also work on POSIX
@@ -38,6 +41,22 @@ def test_variant_bool(self):
         vb.value = []
         self.assertIs(vb.value, False)
 
+    def assertIsSigned(self, ctype):
+        self.assertLess(ctype(-1).value, 0)
+
+    def assertIsUnsigned(self, ctype):
+        self.assertGreater(ctype(-1).value, 0)
+
+    def test_signedness(self):
+        for ctype in (wintypes.BYTE, wintypes.WORD, wintypes.DWORD,
+                     wintypes.BOOLEAN, wintypes.UINT, wintypes.ULONG):
+            with self.subTest(ctype=ctype):
+                self.assertIsUnsigned(ctype)
+
+        for ctype in (wintypes.BOOL, wintypes.INT, wintypes.LONG):
+            with self.subTest(ctype=ctype):
+                self.assertIsSigned(ctype)
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2022-09-26-21-18-47.gh-issue-60580.0hBgde.rst

@@ -0,0 +1,3 @@
+:data:`ctypes.wintypes.BYTE` definition changed from
+:data:`~ctypes.c_byte` to :data:`~ctypes.c_ubyte` to match Windows
+SDK. Patch by Anatoly Techtonik and Oleg Iarygin.