sizeof(struct s1) = 14
offsetof(x) = 0, offsetof(y) = 2, offsetof(z) = 6
s1 = {x = 123, y = -456, z = 3.14159}

sizeof(struct s2) = 16
&s2 mod 16 = 0
offsetof(x) = 0, offsetof(y) = 2, offsetof(z) = 6
s2 = {x = 57, y = -456, z = 3.14159}

sizeof(struct s3) = 31
offsetof(s) = 29
s3 = {x = 123, y = 45678, z = 2147483649, v = -456, w = -1234567, p is ok, t = {111,222,333}, s = {'o','k'}}

sizeof(struct s4) = 16
offsetof(x) = 0, offsetof(y) = 4, offsetof(z) = 8
s4 = {x = 123, y = -456, z = 3.14159}

sizeof(struct s5) = 14
offsetof(x) = 0, offsetof(y) = 2, offsetof(z) = 6
s5 = {x = 123, y = -456, z = 3.14159}

sizeof(struct s6) = 14
offsetof(x) = 0, offsetof(y) = 2, offsetof(z) = 6
s62 = {x = 123, y = -456, z = 3.14159}