std::unexpected

Defined in header <exception>
void unexpected();		(until C++11)
[ [noreturn] ] void unexpected( ) ;		(deprecated in C++11) (removed in C++17)

std::unexpected() is called by the C++ runtime when a dynamic exception specification

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

If a destructor reset the unexpected handler during stack unwinding and the unwinding later led to unexpected	(until C++11)
If a destructor reset the unexpected handler during stack unwinding, it is unspecified which handler is called if the unwinding later led to unexpected being called.	(since C++11)

Exceptions

Throw any exception thrown by the currently installed std::unexpected_handler.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2111	C++11	effect of calling std::set_unexpected during stack unwinding differs from C++98 and breaks some ABIs	made unspecified

See also

unexpected (C++23)	represented as an unexpected value (class template)
unexpected_handler (deprecated in C++11)(removed in C++17)	the type of the function called by std::unexpected (typedef)