[bug fix??] Fishy code in tts_cirtual_copyslot()

Hello,

In the following code in execTuples.c, shouldn' srcdesc point to the source slot's tuple descriptor? The attached fix passes make check. What kind of failure could this cause?

BTW, I thought that in PostgreSQL coding convention, local variables should be defined at the top of blocks, but this function writes "for (int natts;". I didn't modify it because many other source files also write in that way.

--------------------------------------------------
static void
tts_virtual_copyslot(TupleTableSlot *dstslot, TupleTableSlot *srcslot)
{
TupleDesc srcdesc = dstslot->tts_tupleDescriptor;

Assert(srcdesc->natts <= dstslot->tts_tupleDescriptor->natts);

tts_virtual_clear(dstslot);

slot_getallattrs(srcslot);

for (int natt = 0; natt < srcdesc->natts; natt++)
{
dstslot->tts_values[natt] = srcslot->tts_values[natt];
dstslot->tts_isnull[natt] = srcslot->tts_isnull[natt];
}
--------------------------------------------------

Regards
Takayuki Tsunakawa