std::unexpected_handler(3)

NAME
std::unexpected_handler - std::unexpected_handler

Synopsis
   Defined in header <exception>
   typedef void (*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.

See also
   unexpected function called when dynamic exception specification is
   (removed in C++17) violated
                        (function)
   set_unexpected changes the function to be called by std::unexpected
   (removed in C++17) (function)
   get_unexpected obtains the current unexpected_handler
   (C++11)(removed in C++17) (function)