C29 is shaping up to be some quality of life changes. And it looks like clang has a lot of it implemented already. GCC seems to be implementing some of them. `countof(thing)` seems handy so I don't have to define some constant and use them in both places.

Not having to write

    #define len(x) sizeof(x) / sizeof(*x)

GCC is usually ahead in terms of new C features.