Defined in header
[[noreturn]] void unexpected();
std::unexpected() is called by the C++ runtime when a dynamic exception specification is violated: an exception is thrown from a function whose exception specification forbids exceptions of this type.
std::unexpected() may also be called directly from the program.
In either case,
std::unexpected calls the currently installed std::unexpected_handler. The default std::unexpected_handler calls std::terminate.
(deprecated since C++11)
| the type of the function called by std::unexpected |