Zero-cost abstraction is what you get when your abstraction gets compiled away to nothing. Like properly written value wrappers in C++, or (presumably) newtype in Rust. These things disappear from final assembly.

In that regard, exceptions are interesting as if you're on the happy path (which should be 99.999% of the time - a normal program that uses exceptions as error handling method should not encounter any exception if you do a `catch throw` on an average run of the software), they can cost less than return-value-based error handling (https://nibblestew.blogspot.com/2017/01/measuring-execution-...). If you're on a "sad path", though, they will cost more.

What is pretty sure is that since compilers learned to put the "sad" path in .cold section, the code size issue has become a 100% non-issue, the "sad" path won't bloat the hot, exception-less path ; in my experience, exceptions are in cases that matter a negative-cost abstraction.

  struct Error* create_error(const char *msg) {
    struct Error *e = malloc(sizeof(struct Error));
    e->msg = strdup(msg);
    return e;
  }