[Accepted as a DR at the November, 2017 meeting.]

According to the current rules for structured binding declarations, the user-defined case declares the bindings as variables of reference type. This presumably makes an example like the following valid:

   auto [a] = std::tuple<int>(0);
   extern int &&a; // ok, redeclaration, could even be in a different TU 

This seems unreasonable, especially in light of the fact that it only works for the user-defined case and not the built-in case (where the bindings are not modeled as references).