A modern cfront is nearly impossible. Templates make it hella-hard.
really? how is that?
Everything is possible. It is software, after all. But it is not
practical. The
original cfront was, to some extent, a cpp(1) on steroids. AFAIR, it
operated
by manipulating C source code.
With modern C++ things like inlines, templates and concepts operate at
a level of AST. I guess one could use C for an AST representation, but
that would be a pretty daring feat.