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> "char data[0]" is not supported by the C standard, it's a GNU extension I
> believe.
> You can use 'offsetof' to determine the offset of a structure member, you
> can do something like
> struct STRING
> {
>   size_t length;
>   char data[1];
> }
> struct STRING* build_string(size_t size, const char* data)
> {
>   struct STRING* p = (struct STRING*)malloc(offsetof(struct STRING, data) +
> size);
>   p->length = size;
>   memcpy(p->data, data, size);
>   return p;

"char data[0]" is not standard C, and "char data[]" is not standard C89.
Lua uses exactly the technique described here, with offsetof, to
allocate Udata, CClosure, and LClosure without wasting memory.

-- Roberto