The fact that the code was complicated was sort of the point; the generic deriving code in the Rust compiler is in general a very tricky and confusing area and pretty complicated to deal with. In C++ I would have been very careful around code like this and not introduced new pointers. In Rust, I could do this without being afraid of memory issues.

You're not supposed to understand the actual code in the blog post; there's heaps of context and explanations of compiler internals I didn't want to do. I tried to make it clear what task I wanted to do, and how the compiler helped me carry it out; the code is just there to give a better idea of what was going on. If you read closely I do mention that a lot of things should be ignored, there.

The post also walks through the explanations of why the lifetimes work out that way, but that's more for the readers' edification -- I didn't need to actually figure anything out whilst working on it; the explanations are something I thought about later.