[clang-cl] missing `__threadid` `_threadid` and `__threadhandle` in `stddef.h`

[QianNangong]

MSVC provides two functions and one macro inside ucrt's stddef.h

_ACRTIMP extern unsigned long  __cdecl __threadid(void);
#define _threadid (__threadid())
_ACRTIMP extern uintptr_t __cdecl __threadhandle(void);

However when I choose clang-cl toolset, they are no longer available.

[frederick-vs-ja]

I'm inclined not to add thread-related, non-standard stuffs to <stddef.h>. These functions are poorly documented (merely mentioned) in https://learn.microsoft.com/en-us/cpp/c-runtime-library/internal-crt-globals-and-functions?view=msvc-170.

You can use GetCurrentThreadId instead of __threadid as they're equivalent, while __threadhandle is equivalent to reinterpret-casting the return value of GetCurrentThread to uintptr_t.

[QianNangong]

Oops..
They are everywhere in my company's 25 years old code and I'm working hard to migrate them to modern C++ and toolchains.
May doing a global replacement is fine for me.