Function read_fixed_primitive_fields

cpp/fory/serialization/struct_serializer.h:3817–3828

/// Optimized: uses compile-time offsets and updates reader_index once at end.
template <typename T, size_t... Indices>
FORY_ALWAYS_INLINE void
read_fixed_primitive_fields(T &obj, Buffer &buffer,
                            std::index_sequence<Indices...>) {
  using Helpers = CompileTimeFieldHelpers<T>;
  const uint32_t base_offset = buffer.reader_index();

  // Read each field using helper function - no lambda overhead
  (read_single_fixed_field<T, Indices>(obj, buffer, base_offset), ...);

  // Update reader_index once with total fixed bytes (compile-time constant)
  buffer.reader_index(base_offset + Helpers::leading_fixed_size_bytes);
}

/// Read a single varint field at a given offset.
/// Does NOT update reader_index - caller must track offset and update once.