https://svn.boost.org/trac10/ticket/10981 <p> Repro: </p> <pre class="wiki">#include &lt;boost/function.hpp&gt; int main() { boost::function&lt;int()&gt; foo; foo = nullptr; } </pre><p> This appears to hit the operator= overload taking a functor. An overload for std::nullptr_t should probably be added. </p> <p> There appears to be a similar issue with the constructor as well: </p> <pre class="wiki">#include &lt;boost/function.hpp&gt; int main() { boost::function&lt;int()&gt; foo = nullptr; } </pre> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/10981 Trac 1.4.3