Preprocessor macro trick detecting argument is exactly 0, NULL, or nullptr

0__README.txt

Goal: 

Define a preprocessor ("function-like") macro such that when the argument
is exactly one of: "0", "NULL", "nullptr" (without the quotes), the 
macro is expanded to "1" (without the quotes), otherwise it should expand
to "0" instead.

References and useful information:

https://stackoverflow.com/questions/32399191/va-args-expansion-using-msvc
https://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly

test.cpp

// Goal: 
//
// Define a preprocessor ("function-like") macro such that when the argument
// is exactly one of: "0", "NULL", "nullptr" (without the quotes), the 
// macro is expanded to "1" (without the quotes), otherwise it should expand
// to "0" instead.
//
// The following attempt is tested on 
// Microsoft Visual Studio Community Edition 2017, Version 15.6.3
//
// This attempt contains a workaround for MSVC, therefore it will not work
// on other compilers unless modifications are made.
//
// To see preprocessor output. use /E option with MSVC compiler.
//
// Suggestion: 
// (1) Turn off precompiled header for the cpp file containing this macro 
//     test code, 
// (2) Don't put any C++ code other than preprocessor definitions in the 
//     test cpp file.

#define GET0(arg0, ...) arg0
#define GET1(arg0, arg1, ...) arg1
#define GET2(arg0, arg1, arg2, ...) arg2

// (This description is written by a novice, and may contain technical errors.)
//
// In Microsoft Visual C++, the expansion of __VA_ARGS__ is treated as one token.
// As a result, when __VA_ARGS__ is used in invoking another preprocessor macro, 
// the expansion of __VA_ARGS__ will be used to populate exactly one input 
// argument for the macro being invoked.
//
// Thus, for Microsoft Visual C++, the correct way to implement the 
// re-evaluation macro is:
//      #define RE_EVALUATE(x) x
// but not
//      #define RE_EVALUATE(...) __VA_ARGS__
// if the argument is known to contain __VA_ARGS__.
// 
// References
// https://stackoverflow.com/questions/32399191/va-args-expansion-using-msvc
// https://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly
//
#define PRETREAT_VA_ARGS_MSVC(x) x

#define KNOWN_NULL(x) 0, 0
#define KNOWN_0(x) 0, 0
#define KNOWN_nullptr(x) 0, 0
#define GET2_MSVC(...) PRETREAT_VA_ARGS_MSVC(GET2(__VA_ARGS__))

#define IS_KNOWN(x) GET2_MSVC(KNOWN_##x(x), 1, 0)

#pragma message( IS_KNOWN(z) )
#pragma message( IS_KNOWN(imgproc) )
#pragma message( IS_KNOWN(std::cout) )
#pragma message( IS_KNOWN(0) )
#pragma message( IS_KNOWN(nullptr) )
#pragma message( IS_KNOWN(NULL) )

#if 0
// Preprocessor output
>#pragma message(0)
>#pragma message(0)
>#pragma message(0)
>#pragma message(1)
>#pragma message(1)
>#pragma message(1)
#endif