Technically you can have some sort of command in your C++ program to make it
fork itself, that is restart itself disk, maybe after freeing non-shareable resources like listening sockets. One could even imagine that this command includes self-recompilation by invoking
make (or whatever your build system is).
An alternative is to have your program expose its pid somewhere, and your make file could send a signal to that pid when a new version is ready. The advantage is that if your program crashes on startup, you don't have to do something different to restart it.
If your application has to include an "auto-update" feature (like browsers), use that instead - its certainly better to eat your own dog food. Maybe just hack it a little bit so that you can force a check programmatically (e.g. by sending it a signal) and so that it connects to a local updates server.
It is true that C++ is an overly complicated language; if you don't need maximal performance, you have a lot of AoT languages that are a bit slower ( something around 0.5 C ) but more "user-friendly". In particular, if you are into servers and want fast edit-compile-run loops, Go might be a good choice.