id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11670	Boost intrusive constructors should be constexpr	ben.maurer@…	Ion Gaztañaga	"Boost intrusive constructors should be marked constexpr. Doing so would allow for their use in static variables without SIOF. As an example consider this program that uses a simple linked list

http://ideone.com/O5YWM8

because the LinkedList constructor is not constexpr, the variable gets initialized in file declaration order -- after my_crazy_variable. Therefore even though my_crazy_variable's ctor pushes something on to the list, it gets lost when the list is initialized and the program crashes due to being unable to pop a value.

However, if you declare LinkedList's constructor constexpr the list is initialized in the zero initialization phase (http://en.cppreference.com/w/cpp/language/initialization#Non-local_variables). This means that the linked list can be used in other constructors without worrying about initialization order.

While my example is obviously not a sane use case, imagine a linked list that registers all live Widget objects. if somebody creates a widget during static initialization they could encounter the same problem.

A side benefit to doing this is that code size is reduced as the code to initialize the linked list is not created"	Bugs	new	To Be Determined	intrusive	Boost 1.60.0	Problem