Микроконтроллеры

The #pragma pack directive affects declarations of structures following the pragma directive to the next #pragma pack or the end of the compilation unit. Note: This can result in significantly larger and slower code when accessing members of the structure. Use either _ _packed or #pragma pack to relax the alignment restrictions for a type and the objects defined using that type. Mixing _ _packed and #pragma pack might lead to unexpected behavior.

И все вполне работает. А компилятор не умничает, а выдает диагностику.