Compiling CPP to DYLIB on Mac

[Wiggliestone]

Given CPP file main.cpp to compile:
g++ -c -fdeclspec main.cpp

Then to produce DYLIB:
g++ -dynamiclib -undefined suppress -flat_namespace *.o -o main.dylib

[Wiggliestone]

main.cpp as follows:

#define EXTERN_DLL_EXPORT extern "C" __declspec(dllexport)

EXTERN_DLL_EXPORT int testDownCall(int i){
    return i*i;
}

int main(){
    
    return 0;
}