prog.cpp

#include <iostream>

class Vector
{
    public:
        float x, y;
};

class Point
{
    public:
        Point AddVector(Vector v);

        float x, y;
};

Point Point::AddVector(Vector v)
{
}

// `g++ prog.cpp -o bin/prog` results in:
//
// /usr/lib/gcc/x86_64-pc-cygwin/4.8.3/../../../../lib/libcygwin.a(libcmain.o): In function `main':
// /usr/src/debug/cygwin-1.7.32-1/winsup/cygwin/lib/libcmain.c:39: undefined reference to `WinMain'
// /usr/src/debug/cygwin-1.7.32-1/winsup/cygwin/lib/libcmain.c:39:(.text.startup+0x7e): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `WinMain'
// collect2: error: ld returned 1 exit status