ftor | ftor enables ML-like type | Functional Programming library

I have come up with some code which makes use of a self-referential struct (the 1st element of the struct is a pointer to a function that takes an instance of the struct as its one and only argument).

It has been useful for passing disparate routines to another to invoke because the invoking routine doesn't need to know the exact argument makeup of the passed routines (see the process_string call sites in the code below). The passed/invoked routines themselves are responsible for unpacking (casting) the args in a way meaningful to them.

At the bottom of this post is some sample code making use of this technique. It produces the following output when compiled with gcc -std=c99 -Wpedantic -Wall -Wextra -Wconversion:

The following code includes a complete description of the problem as a TODO. Included are cut/pasteable command lines to compile the code (without error). Child instances contain their own name, and the initializer should copy it. Child instances also contain a pointer to their Parent this instance. Neither of these should print garbage. Child also uses its Parent instance pointer to print the parent name. This name is initialized by the Parent ctor, and so should not print as garbage. I even ran it through clang with -fsyntax-only, without reported warning/error. I must be missing something. Help would be appreciated.