[Bug libstdc++/55043] [4.7/4.8 Regression] issue with nesting unordered_map containing unique_ptr into vector

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55043

--- Comment #9 from Marc Glisse <glisse at gcc dot gnu.org> 2012-10-24 03:04:16 UTC ---
(In reply to comment #8)
> is this a bug in is_constructible?

I don't think so. The implementation of the copy constructor is irrelevant,
only the prototype matters to determine copy-constructibility. The "best"
changing the trait could get is a hard (not sfinae) error...