Currently, Argument Clinic generates initialization of ULONG_PTR arguments using PyLong_AsVoidPtr(). The reason is sizeof(ULONG_PTR) == sizeof(void*) akin to C99 uintptr_t.

However, a compiler warns that implicit conversion of a pointer to a pointer-sized integer is not the best practice. This is relevant for _overlapped.CreateIoCompletionPort():

I see three ways to fix it in ULONG_PTR Argument Clinic converter and need an opinion on how to address the warning best:

• generate in-place cast: CompletionKey = (ULONG_PTR)PyLong_AsVoidPtr(args[2]); or
• add a private Windows-only #define _PyLong_AsUlongPtr(arg) (ULONG_PTR)PyLong_AsVoidPtr(arg) macro so the generated line becomes CompletionKey = PyLong_AsUlongPtr(args[2]); or
• add a public Windows-only PyLong_AsUlongPtr entity and document it so Python integrators and module authors also can work with this volatile WinAPI type

Linked PRs

• gh-95417: Quick fix of ULONG_PTR differs in levels of indirection from void * #95538
• gh-95417: Apply a proper fix for previously fast-fixed ULONG_PTR differs in levels of indirection from void * #95518