struct metadata {
   u2 lel;
   enum {
      STR_TERMINATED,
      STR_DELIMITED
   } u1 type;
   struct {
      u8 smth;
   } test;
   u8 encoding[32][sizeof("foo")];
   u1 blaz[builtin(1, 2, "foo", 'bar')] | hellothere('foobar', 1, 2, "faa");
};

struct utf8_string {
   struct metadata metadata;
   select (((metadata.type))) {
      metadata.STR_TERMINATED)
         struct {
            u8 string['\0'] | encoding(metadata.encoding) str;
         } terminated;
      metadata.STR_DELIMITED)
         struct {
            u32 length;
            u8 string[length] | encoding(metadata.encoding) str;
         } delimited;
   } data;
   u1 foo[((((metadata.test.smth)))) + 5 + 2][4];
};