Function parse

test/base-test.cc:301–303

FMT_BEGIN_NAMESPACE
template <typename Char> struct formatter<test_struct, Char> {
  FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
    return ctx.begin();
  }

  auto format(test_struct, format_context& ctx) const -> decltype(ctx.out()) {
    return copy("test", ctx.out());