Can we add non-Packed structure element to Packed structure

Question

Is it allowed to have non-packed structure member inside a packed structure?

Something like this:

packed struct{
    int a;
    un-packed struct b;
    int c;
};

Answer 1

Yes, it is allowed. The unpacked structure is a normal type from the point of view of the compiler and the packeds structure will, technically, remain packed.

But, in a common sense, the packed structure will not be actually packed - there may be some bytes unused in the unpacked structure and hence in the packed structure.