While not used by the author here, Retro68 is a hobbyist project targeting a modern GCC-based cross-compiler to the classic 68K and PPC Mac environment. https

While not used by the author here, Retro68 is a hobbyist project targeting a modern GCC-based cross-compiler to the classic 68K and PPC Mac environment. https://github.com/autc04/Retro68 https://github.com/autc04/Retro68 So you can write C++17 for System 6 too, if you want.