Macros BMI_SUCCESS and BMI_FAILURE prevent co-inclusion with C++ bmi-cxx/bmi.hxx

[PhilMiller]

The header bmi.h here contains these macro definitions:

#define BMI_SUCCESS (0)
#define BMI_FAILURE (1)

The C++ header bmi.hxx contains declarations of variables in with those exact same names. Thus, if a source file says

#include <bmi.h>
#include <bmi.hxx>

It will fail to compile, because the compiler will see code that preprocesses to

namespace Bmi {
  const int (0) = 0;
  const int (1) = 1;
}

This is a potential problem for codebases that want to support BMI modules written in either language, and not have to meticulously separate where the two different BMI language binding headers get included, or in which order.

[PhilMiller]

The seemingly natural solution to this would be to replace the macros with

const static int BMI_SUCCESS = 0;
const static int BMI_FAILURE = 1;