id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8596	With C++0x enabled, boost::packaged_task stores a reference to function objects, instead of a copy	Kees-Jan Dijkzeul <kees-jan.dijkzeul@…>	viboes	"I have build a Treadpool using boost::thread. In porting it to boost 1.53, I've found a regression.

Consider attached test-program. It runs correctly on boost 1.49 and earlier. It runs correctly on boost 1.53, with C++0x disabled. With C++0x enabled, it crashes due to an uncaught exception ""call to empty boost::function""

Failure has been observed on Ubuntu Saucy, I.e. boost 1.53, gcc 4.8.0, linux kernel 3.9.0.

After some debugging, I believe the problem is caused by packaged_task storing a reference to the boost::function object, instead of a copy. As the boost::function object is a temporary, this leads to undefined behavior further on.

I'm guessing this problem is introduced in [81117] By below patch to boost/thread/future.hpp
{{{
 #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
         template <class F>
         explicit packaged_task(BOOST_THREAD_RV_REF(F) f
             , typename disable_if<is_same<typename decay<F>::type, packaged_task>, \
dummy* >::type=0  )
         {
-          typedef typename remove_cv<typename remove_reference<F>::type>::type FR;
+          //typedef typename remove_cv<typename remove_reference<F>::type>::type FR;
+          typedef F FR;
 #if defined BOOST_THREAD_PROVIDES_SIGNATURE_PACKAGED_TASK
....
}}}

Attached: Small application showing the problem

For original code please visit https://github.com/kees-jan/scroom/blob/master/inc/scroom/impl/threadpoolimpl.hh#L90"	Bugs	closed	Boost 1.54.0	thread	Boost 1.53.0	Problem	fixed