[user911302966]

You subverted your argument by including the term 'low-level'. Of course, that's all written freshly in C to this day.

Assuming that you meant only 'non-trivial': aside from the embedded space, C and GCC still represent the first-tapped resource in many companies. C is terse, well-known, fast and predictable.

I'd go marginally further and claim that, done correctly, gmake and a proper directory hierarchy remain the most effective way of organizing and maintaining a large software project.