> You don't generally need specific versions of GCC or Clang to build it I'm pretty sure.

You need a C11 compiler these days with loads of non-standard extensions. Note, for a very long time, one couldn't compile the Linux kernel with clang because it lacked this GCC specific behavior.

I'm not really sure you can turn around and say -- Oh, but now we feel differently about the C standard -- given how much is still non-standard. For instance, I don't believe Intel's C compiler will compile the kernel, etc.