constant_array::data is not constexpr

[yfeldblum]

constant_array::data is not constexpr

fatal/container/constant_array.h:45:54: note: non-constexpr function 'data' cannot be used in a constant expression
  static constexpr value_type const *data() { return get.data(); }
                                                     ^
fatal/type/deprecated/constant_sequence.h:658:50: note: in call to 'data()'
  static constexpr type const *z_data() { return z_array<Suffix...>::data(); }
                                                 ^

Tools: clang-v3.9.0.

Seeing this error when making a library that iterates over the types generated by Thrift static reflection.