Proposed resolution:

1. In both [tuple.general]/2 and [tuple.special] change

   template <class Swappable... Types>
   void swap(tuple<Types...>& x, tuple<Types...>& y);
   

2. In [tuple.tuple], class tuple definition and in [tuple.swap], change

   requires Swappable<Types>...void swap(tuple&);
   

3. In [tuple.swap] remove the current requires-clause, which says:

   Requires: Each type in Types shall be Swappable

[ Batavia (2009-05): ]

We observed that all the proposed changes have already been applied to the Working Draft, rendering this issue moot.

Move to NAD.

[ 2009-05-01 Daniel adds: ]

As of the recent WP (N2857), this issue is now completely covered by editorial changes (including the third bullet), therefore I unconditionally recommend NAD.

[ Post Summit Daniel adds ]

This is now NAD Editorial (addressed by N2844) except for item 3 in the proposed wording.

Issue 522 was accepted after tuple had been conceptualized, therefore this step needs to be completed.