[PATCH] [libc++] Make std::deque instantiable with incomplete element type

[Howard Hinnant]

On Sep 21, 2013, at 5:53 PM, Chandler Carruth <chandlerc at google.com> wrote:

> 
> On Sat, Sep 21, 2013 at 2:48 PM, Howard Hinnant <howard.hinnant at gmail.com> wrote:
> I really like this patch.  It is a nice piece of work.  Unfortunately I think I'm going to have to decline it for ABI reasons.
> 
> Ouch.
> 
> Do you see any path forward here or solution to preserve ABI? We ran into a nontrivial amount of code which ended up relying on this.

The easiest thing I can think of is to wait until libc++ is ready to make ABI breaking changes across the board, and then increment _LIBCPP_ABI_VERSION.

I've wondered if Peter's fix would work if we gratuitously restored the unneeded template parameter on __deque_iterator just for the purpose of ABI stability.  I don't know the answer to this question, and won't personally have time to investigate it at this time.

Howard