message: Fix compiler warnings on EnumTags
diff: @@ -25,7 +25,7 @@ class EnumTags {
  using reverse_iterator = std::reverse_iterator<iterator>;
  template <size_t... LN>
  - explicit constexpr EnumTags(const char (&...literals)[LN]) : _tags{literals...} {}
  + explicit constexpr EnumTags(const char (&...literals)[LN]) : _tags{{literals...}} {}
  constexpr const char* tag(E etag) const { return tag(int_type(etag)); }
  constexpr const char* tag(int_type idx) const { return _tags[idx]; }
  