@MaddieM4 @wbrawner @dalias @ell1e @Kroc @xgranade C compilers are easy to write. Good C compilers are a different story.
For Fuzix I wrote my own (in part because nobody else fitted an ANSIish C compiler in to a 64K address space machine).
It's C89 without bitfields basically, because bitfields are evil and everything added to C post C89 except "..." is wrong 8)
You could add C99isms to it but either way C compilers are not tricky, codegen is.