boost.mpi miscompiles with gcc4.6 and option -std=c++0x

[christophe.prudhomme@…]

Hello

boost.mpi with gcc-4.6 and the option -std=c++0x don't get well together here is a very simple example

---

#include <boost/mpi.hpp>

---

the issue arises with the use of the -std=c++0x flag to use

the new c++ standard. It use to work properly with previous g++ version

compile without -std=c++0x g++ -I/usr/include/mpi -c t.cpp no errors

try compiling with -std=c++0x

g++ -I/usr/include/mpi -std=c++0x -c t.cpp

2011-05-12 22:40:17

prudhomm pts/28 In file included from /usr/include/c++/4.6/memory:67:0,

from /usr/include/boost/mpi/allocator.hpp:18, from /usr/include/boost/mpi.hpp:22, from t.cpp:3:

/usr/include/c++/4.6/bits/stl_uninitialized.h: In function ‘void std::uninitialized_default_n_a(_ForwardIterator, _Size, _Allocator&) [with _ForwardIterator = char*, _Size = long unsigned int, _Allocator

boost::mpi::allocator<char>]’:

/usr/include/c++/4.6/bits/vector.tcc:474:8: instantiated from ‘void std::vector<_Tp, _Alloc>::_M_default_append(std::vector<_Tp, _Alloc>::size_type) [with _Tp = char, _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, _Alloc>::size_type = long unsigned int]’ /usr/include/c++/4.6/bits/stl_vector.h:592:4: instantiated from ‘void std::vector<_Tp, _Alloc>::resize(std::vector<_Tp, _Alloc>::size_type) [with _Tp = char, _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, _Alloc>::size_type = long unsigned int]’ /usr/include/boost/mpi/detail/packed_oprimitive.hpp:96:46: instantiated from here /usr/include/c++/4.6/bits/stl_uninitialized.h:576:6: error: no matching function for call to ‘boost::mpi::allocator<char>::construct(char*)’ /usr/include/c++/4.6/bits/stl_uninitialized.h:576:6: note: candidate is: /usr/include/boost/mpi/allocator.hpp:168:8: note: void boost::mpi::allocator<T>::construct(boost::mpi::allocator<T>::pointer, const T&) [with T = char, boost::mpi::allocator<T>::pointer = char*] /usr/include/boost/mpi/allocator.hpp:168:8: note: candidate expects 2 arguments, 1 provided

[petar.marendic@…]

My fix for this was to define a corresponding member function of the class allocator in boost/mpi/allocator.h:

/* Default construct a value of type T at the location referenced by p. */

void construct(pointer p) {

new ((void *)p) T();

}

[jwakely.boost@…]

This is a GCC 4.6 bug that only affects -std=c++0x mode.

In C++0x mode we assume all allocators provide the C++11 allocator interface, which is a bad assumption. The fix (which I've implemented in GCC 4.7) is to use std::allocator_traits to support allocators without the full interface.

I'm going to open a GCC bug and will update this ticket with a link.

A workaround is to provide construct(pointer) in the MPI allocator, or even to provide the C++11-style:

template<typename... Args> void construct(T*, Args&&...);

[jwakely.boost@…]

​http://gcc.gnu.org/PR51626

[Mateusz Loskot]

Jonathan has fixed the GCC ​Bug 51626 linked above. The fix will be in GCC 4.6.3

[smr@…]

Can this be applied for release 1.49, please?