Using noexcept for functions that do not throw exceptions
Exception specification is a language feature that can enable performance improvements, but on the other hand, when done incorrectly, it can abnormally terminate the program. The exception specification from C++03, which allowed you to indicate what types of exceptions a function could throw, was deprecated in C++11 and removed in C++17. It was replaced with the C++11 noexcept specifier. Moreover, the use of the throw() specifier to indicate that a function throws, without indicating what exception types have also been deprecated in C++17 and completely removed in C++20. The noexcept specifier only allows you to indicate that a function does not throw exceptions (as opposed to the old throw specifier, which could indicate the list of types a function could throw). This recipe provides information about the modern exception specifications in C++, as well as guidelines on when to use them.
