id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
12577	Null reference in pair.hpp triggers runtime warning with -fsanitize=undefined	antoinep92@…	Ion Gaztañaga	"I tagged 1.62 which is where I discovered the issue, but master at github seems affected as well.

Consider this minimal file:
{{{
#include <boost/container/flat_map.hpp>
int main() { return 0; }
}}}

When built with gcc 6.2 and undefined sanitizers, `g++ -fsanitize=address`, the resulting executable triggers the following warning at runtime during static initialization:
{{{
/usr/include/boost/container/detail/pair.hpp:85:30: runtime error: reference binding to null pointer of type 'const struct piecewise_construct_t'
}}}

This doesn't happen with clang 3.9, so it *might* be a bug in gcc, but when looking at the boost code, I'd say gcc is right. Indeed, in `container/detail/pair.hpp` (line 85 in 1.62 and master), the static global variable `boost::container::piecewise_construct` is defined, of type `const std::piecewise_construct_t &`, and value `*boost::container::std_piecewise_construct_holder<0>::dummy`, defined in the same file, but (as far as I can tell), uninitialized.

I'm not well positioned to assess the bug severity: either the null/uninitialized reference is never used, and the gcc warning can be ignored (although it's annoying); or there are situations the reference's address is dereferenced, and this can lead to crashes."	Bugs	closed	To Be Determined	container	Boost 1.62.0	Problem	fixed