100% of platforms that Zig & Rust run on already have a C compiler installed, though. A c compiler being present is the baseline assumption. If Zig existed in places C doesn't and I wanted to write C for that platform then having Zig CC would be an advantage. But such a situation doesn't currently exist and seems unlikely to ever exist? Especially in the context of a library/module porting to Zig or Rust piecemeal, though, then I already obviously have a working C compiler & build toolchain in place since that's my start point.