gh-152433: Windows: _ctypes module: improve UWP compatibility

Author: thexai

Misc/NEWS.d/next/Windows/2026-07-01-17-00-52.gh-issue-152433.kSd1bW.rst

@@ -0,0 +1 @@
+``_ctypes`` module: improve UWP compatibility.

Modules/_ctypes/callproc.c

@@ -1082,8 +1082,7 @@ void _ctypes_extend_error(PyObject *exc_class, const char *fmt, ...)
 }
 
 
-#ifdef MS_WIN32
-
+#ifdef MS_WINDOWS_DESKTOP
 static PyObject *
 GetComError(ctypes_state *st, HRESULT errcode, GUID *riid, IUnknown *pIunk)
 {
@@ -1337,9 +1336,11 @@ PyObject *_ctypes_callproc(ctypes_state *st,
 
 #ifdef MS_WIN32
     if (iid && pIunk) {
+#ifdef MS_WINDOWS_DESKTOP
         if (*(int *)resbuf & 0x80000000)
             retval = GetComError(st, *(HRESULT *)resbuf, iid, pIunk);
         else
+#endif
             retval = PyLong_FromLong(*(int *)resbuf);
     } else if (flags & FUNCFLAG_HRESULT) {
         if (*(int *)resbuf & 0x80000000)
@@ -1417,10 +1418,14 @@ static PyObject *load_library(PyObject *self, PyObject *args)
         return NULL;
 
     Py_BEGIN_ALLOW_THREADS
+#ifndef MS_WINDOWS_DESKTOP
+    hMod = LoadPackagedLibrary(name, 0);
+#else
     /* bpo-36085: Limit DLL search directories to avoid pre-loading
      * attacks and enable use of the AddDllDirectory function.
      */
     hMod = LoadLibraryExW(name, NULL, (DWORD)load_flags);
+#endif
     err = hMod ? 0 : GetLastError();
     Py_END_ALLOW_THREADS