pack struct / avoid padding

I have following struct:

struct SkipListNode{
    void        *data;      // 8 bytes
    uint8_t     size;       // 1 byte
    // 7 bytes padding here...
    void        *next[1];   // dynamic array, 8 bytes each "cell"

I am using malloc() and I am allocating more space than sizeof(SkipListNode), so I am extending the next[] array.

I want to avoid 7 bytes waste. I can completely remove size field, but then I should keep single NULL (8 bytes) at the end of the array. However this does not help reducing the size.

Shall I use __ attribute__((__ packed__)) or there some different way I could do the trick?

This must be compiled under C and C++ as well.

Compiler is gcc.

Source: gcc

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