This issue is caught and flagged by clang-tidy. Though technically the standard says it is in valid but un-specified state. Because of short string optimisation, the move might be possibly a copy, so one should not rely on the contents being empty.

Clang tidy covers only the most trivial use after move scenarios. It's useful coverage but isn't and never will be complete like the rust borrow checker.

No, you can absolutely use it (but you most likely want to clear() or assign an empty string to it before doing e.g. push_back as move does not necessarily clear the moved-from object - std::move(some_int) won't clear the int)

I mean, it won't have a useful value, so I need to re assign to it, at which point I could just be using a new variable right?

It might not be null, but I can't do much more with it than I can with null. I need to assign something new first

> I mean, it won't have a useful value, so I need to re assign to it, at which point I could just be using a new variable right?

I have a hard time understanding why "I could just be using a new variable" follows from "it won't have a useful value".