ref: 1bc054f7b7f8cd2fa8eea85929bf6d06f8bf787f dir: /tests/execute/0043-union.c/
int main() { union { int a; int b; } u; u.a = 1; u.b = 3; if (u.a != 3 || u.b != 3) return 1; return 0; }