Memory leak when copying empty boost::container::vector

[onlyone@…]

Consider the following simple program:

#include <boost/container/vector.hpp>

int main() {
    while (true) {
        boost::container::vector<int> vec;
        boost::container::vector<int> vec2(vec);
    }
}

With Boost 1.54.0, this leaks an unbounded amount of memory. The copy contructor of boost::container::vector performs an allocation (which in this case asks for 0 bytes), and sets the capacity of the new vector the size of this allocation (0 elements), and since the capacity is 0, the destructor of vec2 does not deallocate this memory.

A simple patch is attached which disables allocation when the requested size is 0. This may not be the optimal solution (for example, there might be code that subsequently reads from m_start and expects it to contain a valid value (I have not yet studied the code sufficiently to know)). Even so, this is a major issue, and so I am reporting it even without a fully tested patch.

Evan Wallace

[onlyone@…]

Patch that disables allocation when space for 0 elements is needed.

[Ion Gaztañaga]

(In [85964]) Default initialization for vector-like containers Complexity guarantees for associative container constructors and ordered input ranges Added benchmark for associative containers Fixes #9166