Forward declarations from std:: not allowed in libc++

[Chris Jefferson]

interprocess uses the forward declarations from std::

template <class T> class allocator;

template <class T> struct less;

template <class T1, class T2> struct pair;

template <class CharType> struct char_traits;

libc++ does not support these. There are various possible fixes. These forward declarations could just be replaced by the headers:

#include <utility> #include <memory> #include <functional> #include <iosfwd>

or we could introduce a macro ( BOOST_ALLOWS_FWD_STD_DECLARATIONS ), or create a detail header for forward declarations.

I am happy to implement any of these, I am interested what the developers of interprocess think.

[Chris Jefferson]

Simple patch to get libc++ working

[Chris Jefferson]

The problem of forwarding headers seems to be causing lots of discussion and not a lot of conclusion.

This simple attached patch disables the forwarding for libc++, the only standard library at present that seems to have trouble with them. I would appreciate it if it could be committed.

[Chris Jefferson]

ping.

Would it be possible to get just a libc++ fix submitted for the next version of boost? I would like to have a more complete fix, but I'm unsure of how to do that in a way that isn't going to require huge amounts of code (as interprocess picks classes out of various headers) and will be agreed on by everyone.

[Ion Gaztañaga]

Patch applied to trunk. After a few cycles, it will be merged to release branch

[Ion Gaztañaga]

Fixed for Boost 1.47