Proposed resolution:

This wording is relative to N4296.

1. Change [allocator.requirements] p9 as indicated:

   -8- An allocator may constrain the types on which it can be instantiated and the arguments for which its construct or destroy members may be called. If a type cannot be used with a particular allocator, the allocator class or the call to construct or destroy may fail to instantiate.

[ 2015-04-01 Library reflector vote ]

The issue has been identified as Tentatively Ready based on six votes in favour.

This issue is a spin-off of issue LWG 2447: It focuses on the observation that [allocator.requirements] p9 (based on the numbering of working draft N4296) gives the template member construct more relaxations than the template member destroy:

An allocator may constrain the types on which it can be instantiated and the arguments for which its construct member may be called. If a type cannot be used with a particular allocator, the allocator class or the call to construct may fail to instantiate.

Construction and destruction of a type T are usually intimately related to each other, so it seems similarly useful to allow the destroy member to fail to instantiate for a possible sub-set of instantiation types.