std::unexpected_handler - cppreference.com

From cppreference.com

typedefvoid(*unexpected_handler)();(deprecated in C++11)
(removed in C++17)std::unexpected_handler is the function pointer type (pointer to function that takes no arguments and returns void), which is installed and queried by the functions

std::set_unexpected

and

std::get_unexpected

and called by

std::unexpected

The C++ implementation provides a default std::unexpected_handler function, which calls

std::terminate()

. If the null pointer value is installed (by means of

std::set_unexpected

), the implementation may restore the default handler instead.

A user-defined std::unexpected_handler is expected to either terminate the program or throw an exception. If it throws an exception, one of the following three situations may be encountered:

1) the exception thrown by std::unexpected_handler satisfies the dynamic exception specification that was violated earlier. The new exception is allowed to escape the function and stack unwinding continues.

2) the exception thrown by std::unexpected_handler still violates the exception specification:

2a) however, the exception specification allows

std::bad_exception

: the thrown exception object is destroyed, and

std::bad_exception

is constructed by the C++ runtime and thrown instead.

2b) the exception specification does not allow

std::bad_exception

std::terminate()

is called.