I was unclear, sorry: I didn't mean to say that the extra braces make it uglier, I meant to point out that something that was described as beautiful was actually flawed.

The flaw was minor in this case because the identifier names and lack of body make the intention clear, but my point is that there are a lot of minor things in C that can come and bite you at any time.

Edit: You are right, I don't see a way this could have been implemented more readable without sacrificing some performance.

First thing I thought of was:

  void cp(const char* from, char* to) {
      while (*from) {
          *to = *from;
          to++;
          from++;
      }
  }

But that does not reduce to the original case.