http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55043
--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-10-24 09:10:38 UTC --- Ah yes, you're right. So to make the testcase compile (which it should) I'd need to use sfinae to disable the container members, which means writing constraints based on CopyInsertable etc which depend on the allocator type, so allocator_traits needs to also use sfinae to disable ill-formed 'construct' calls, which may not be possible to detect, because errors may still not be in the immediate context. Damn.
