This code is very beautifully written, thanks for sharing.
However, you should consult the book "C: Interfaces and Implementations" by Dave Hanson, which has a library called "Arena" that is very similar to your "Pool"s, and it shows a few more tricks to make the code safer and easier to read (Chapters 5+6, 6 in particular).
D. Hanson's book (written in the 'literary programming' style invented by Donal Knuth) also demonstrates having debugging and production implementations for the same C API to catch memory errors, and his book is from 1997:
However, you should consult the book "C: Interfaces and Implementations" by Dave Hanson, which has a library called "Arena" that is very similar to your "Pool"s, and it shows a few more tricks to make the code safer and easier to read (Chapters 5+6, 6 in particular).
D. Hanson's book (written in the 'literary programming' style invented by Donal Knuth) also demonstrates having debugging and production implementations for the same C API to catch memory errors, and his book is from 1997:
(He used to be a SE professor I Princeton before getting hired by Microsoft, I believe.)