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Subject: Re: [boost] [type_traits] has_equal_to< std::vector<T> > always true_
From: Frédéric Bron (frederic.bron_at_[hidden])
Date: 2012-04-30 00:48:37

> We could use <boost/detail/container_fwd.hpp> here (rather like Boost.Hash
> does, which has a similar issue) and get the best of both worlds?  My
> concern about making it a separate header, is that it runs the risk of ADL
> errors if the #includes are inconsistent across translation units.  I assume
> that only forward declarations are needed for the containers?

This looks a very good idea. It is a pity that the standard does not
provide such header as it does for iostreams (iosfwd).
However, I see that <boost/detail/container_fwd.hpp> has some troubles
with many compilers, in particular with g++.
// GNU libstdc++ 3
// Disable forwarding for all recent versions, as the library has a
// versioned namespace mode, and I don't know how to detect it.
This is a major drawback but maybe we can do something for it.

I see also that with the new standard, this header is now not
exhaustive; we have to include all of these:
* <array>
- <deque>
* <forward_list>
- <list>
- <vector>
- <map>
- <set>
* <unordered_map>
* <unordered_set>
- <queue>
- <stack>
- <string>
- <bitset>

*: missing headers in <boost/detail/container_fwd.hpp>


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