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Weird optimization for tuples?


Hello!

I have the following function
std::tuple<uint32_t, uint8_t> getRawIdx(uint16_t tidx) {
  return std::make_tuple(localidx.entries[tidx].indx_ptr,
localidx.entries[tidx].indx_size);
}

Where s is a struct like

typedef struct __attribute__((packed)) {
	uint32_t indx_ptr;
	uint8_t  indx_size;
} _i_idx_entry ;

The error I get is:

 cannot bind packed field
‘((DBIndex*)this)->DBIndex::localidx.DBIndex::_i_idx::entries[((int)tidx)].DBIndex::_i_idx_entry::indx_ptr’
to ‘unsigned int&’

If extend the tuple to include a 3rd field and I return some other thing
it just works:

return std::make_tuple(localidx.entries[tidx].indx_ptr,
                       localidx.entries[tidx].indx_size,
                       tidx, prefb);

I think gcc is trying to do some smart optimization or something and
packed does not work because of tuple alignments not being packed.

Any ideas?
Thanks!
David


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