Code working as C-File but not as C++-File, Error: '__builtin_types_compatible_p' was not declared in this scope

I coded a macro, where I can use any amount of values. If these are floats, they are casted in uint_32 and later all values are used in the method examplefff, where I use varargs to get all values. If I save my following code in a C-file, the compiler doesn't give me any errors and the code works. If I use this macro in a c++-file, it doesn't work anymore. Here is my code:

// Example program
#include <stdio.h>
#include <stdarg.h>
#include <stdint.h>

#define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
#define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
#define NUMARGS(...)  (sizeof((int[]){__VA_ARGS__})/sizeof(int))

// Make a FOREACH macro
#define FE_1(WHAT, X) WHAT(X) 
#define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
#define FE_3(WHAT, X, ...) WHAT(X),FE_2(WHAT, __VA_ARGS__)
#define FE_4(WHAT, X, ...) WHAT(X),FE_3(WHAT, __VA_ARGS__)
#define FE_5(WHAT, X, ...) WHAT(X),FE_4(WHAT, __VA_ARGS__)
#define FE_6(WHAT, X, ...) WHAT(X),FE_5(WHAT, __VA_ARGS__)
//... repeat as needed

#define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME 
#define FOR_EACH(action,...) \
  GET_MACRO(__VA_ARGS__,FE_6,FE_5,FE_4,FE_3,FE_2,FE_1)(action,__VA_ARGS__)

#define NUM_ARGS(...) GET_MACRO(__VA_ARGS__,6,5,4,3,2,1)

#define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)

#define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))



static inline uint32_t TRACE_FLOAT (float f) {
  union { uint32_t u; float f; } u;
  u.f = f;
  return u.u;
}

void examplefff(int numArgs, ...)
{
    printf("n:%u\n", numArgs);

  va_list args;
  va_start(args, numArgs);
  for(int i=0; i<numArgs; i++)
  {
      uint64_t test32 = va_arg(args, uint32_t);
      printf("%u\n", test32);
  }
  va_end(args);
}

int main()
{
        EXAMPLE1(456456,3244);
}

When I compile this file as c-file, the compiler doesn't give me any errors. When I compile this as c++ file(which I need), I get the following output from the compiler.

x86-gcc_6.3.0\bin\gcc testfile.cpp -Wall -std=gnu99 -O2  -o test.exe
cc1plus.exe: warning: command line option '-std=gnu99' is valid for C/ObjC but not for C++
testfile.cpp: In function 'void examplefff(int, ...)':
testfile.cpp:46:28: warning: format '%u' expects argument of type 'unsigned int', but argument 2 has type 'uint64_t {aka long long unsigned int}' [-Wformat=]
       printf("%u\n", test32);
                            ^
testfile.cpp: In function 'int main()':
testfile.cpp:6:51: error: expected primary-expression before 'typeof'
 #define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
                                                   ^
testfile.cpp:7:23: note: in expansion of macro 'IS_FLOAT'
 #define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
                       ^~~~~~~~
testfile.cpp:12:28: note: in expansion of macro 'CONVERT_F'
 #define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
                            ^~~~
testfile.cpp:19:47: note: in expansion of macro 'FE_2'
 #define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
                                               ^~~~
testfile.cpp:27:47: note: in expansion of macro 'FOR_EACH'
 #define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))
                                               ^~~~~~~~
testfile.cpp:25:23: note: in expansion of macro 'EXAMPLE2'
 #define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)
                       ^~~~~~~~
testfile.cpp:53:3: note: in expansion of macro 'EXAMPLE1'
   EXAMPLE1(456456,3244);
   ^~~~~~~~
testfile.cpp:6:63: error: expected primary-expression before 'float'
 #define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
                                                               ^
testfile.cpp:7:23: note: in expansion of macro 'IS_FLOAT'
 #define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
                       ^~~~~~~~
testfile.cpp:12:28: note: in expansion of macro 'CONVERT_F'
 #define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
                            ^~~~
testfile.cpp:19:47: note: in expansion of macro 'FE_2'
 #define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
                                               ^~~~
testfile.cpp:27:47: note: in expansion of macro 'FOR_EACH'
 #define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))
                                               ^~~~~~~~
testfile.cpp:25:23: note: in expansion of macro 'EXAMPLE2'
 #define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)
                       ^~~~~~~~
testfile.cpp:53:3: note: in expansion of macro 'EXAMPLE1'
   EXAMPLE1(456456,3244);
   ^~~~~~~~
testfile.cpp:6:68: error: '__builtin_types_compatible_p' was not declared in this scope
 #define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
                                                                    ^
testfile.cpp:7:23: note: in expansion of macro 'IS_FLOAT'
 #define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
                       ^~~~~~~~
testfile.cpp:12:28: note: in expansion of macro 'CONVERT_F'
 #define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
                            ^~~~
testfile.cpp:19:47: note: in expansion of macro 'FE_2'
 #define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
                                               ^~~~
testfile.cpp:27:47: note: in expansion of macro 'FOR_EACH'
 #define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))
                                               ^~~~~~~~
testfile.cpp:25:23: note: in expansion of macro 'EXAMPLE2'
 #define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)
                       ^~~~~~~~
testfile.cpp:53:3: note: in expansion of macro 'EXAMPLE1'
   EXAMPLE1(456456,3244);
   ^~~~~~~~
testfile.cpp:6:51: error: expected primary-expression before 'typeof'
 #define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
                                                   ^
testfile.cpp:7:23: note: in expansion of macro 'IS_FLOAT'
 #define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
                       ^~~~~~~~
testfile.cpp:11:23: note: in expansion of macro 'CONVERT_F'
 #define FE_1(WHAT, X) WHAT(X)
                       ^~~~
testfile.cpp:12:36: note: in expansion of macro 'FE_1'
 #define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
                                    ^~~~
testfile.cpp:19:47: note: in expansion of macro 'FE_2'
 #define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
                                               ^~~~
testfile.cpp:27:47: note: in expansion of macro 'FOR_EACH'
 #define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))
                                               ^~~~~~~~
testfile.cpp:25:23: note: in expansion of macro 'EXAMPLE2'
 #define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)
                       ^~~~~~~~
testfile.cpp:53:3: note: in expansion of macro 'EXAMPLE1'
   EXAMPLE1(456456,3244);
   ^~~~~~~~
testfile.cpp:6:63: error: expected primary-expression before 'float'
 #define IS_FLOAT(x) (__builtin_types_compatible_p(typeof(x&), float))
                                                               ^
testfile.cpp:7:23: note: in expansion of macro 'IS_FLOAT'
 #define CONVERT_F(x) (IS_FLOAT(x)?TRACE_FLOAT(x): (uint32_t)(x))
                       ^~~~~~~~
testfile.cpp:11:23: note: in expansion of macro 'CONVERT_F'
 #define FE_1(WHAT, X) WHAT(X)
                       ^~~~
testfile.cpp:12:36: note: in expansion of macro 'FE_1'
 #define FE_2(WHAT, X, ...) WHAT(X),FE_1(WHAT, __VA_ARGS__)
                                    ^~~~
testfile.cpp:19:47: note: in expansion of macro 'FE_2'
 #define GET_MACRO(_1,_2,_3,_4,_5,_6,NAME,...) NAME
                                               ^~~~
testfile.cpp:27:47: note: in expansion of macro 'FOR_EACH'
 #define EXAMPLE2(size, ...) (examplefff(size, FOR_EACH(CONVERT_F, __VA_ARGS__)))
                                               ^~~~~~~~
testfile.cpp:25:23: note: in expansion of macro 'EXAMPLE2'
 #define EXAMPLE1(...) EXAMPLE2(NUMARGS(__VA_ARGS__), __VA_ARGS__)
                       ^~~~~~~~
testfile.cpp:53:3: note: in expansion of macro 'EXAMPLE1'
   EXAMPLE1(456456,3244);
   ^~~~~~~~

I want to use the macro 'EXAMPLE' in C-files and C++-Files. So what did I do wrong?

Edit: This is also my first question, so any advice on how to ask better questions is appreciated.