I wrote something similar in C99 as well for another project. Initially, I used the same form used in this blog post however it's easy to see that the ergonomics for accessing the data are pretty terrible.

I eventually moved to a solution where I prepended the capacity and size to the block returned to the caller and then wrote helper functions that accessed/modified these values. This way the caller can access values in the returned array just as they would one returned from malloc.

The code (note, the `vec` type is just a typedef'd `void*`): https://github.com/crossroads1112/marcel/blob/master/src/ds/...

Do you not consider adding a PPA to be straightforward? Or downloading the rustup binary and simply running it?

In Rust, lossy conversions only occur if you you explicitly write `var as type` and even that syntax is limited to certain types e.g. you can't coerce an integer to a function. In order to do something crazy like that, you'd need to call the unsafe `mem::transmute` function. The language cannot be much safer in this regard short of disallowing any sort of type conversions.