rr is a great debugging tool. it records a trace of a program's execution, as well as the results of
any syscalls it executes, so that you can "rewind" while you debug, and get deterministic forward and reverse
instrumented playback. it works with rust, but by default if you try it out, it could be pretty ugly when you
inspect variables. if this bothers you, configure gdb to use a rust pretty-printer
rr is probably in your system's package manager.