[creato]

This is actually C and C++ has not done something similar AFAIK.

[Fulgen]

https://en.cppreference.com/w/cpp/utility/unreachable.html

[hn_go_brrrrr]

Fortunately the major compiler vendors all have. Routing around the standards committee is getting more and more common.

[TuxSH]

C++23 does have std::unreachable (as a function), and its counterpart [[assume(expr)]]