out-of-bounds sequence access when iterating over the result of set_symmetric_difference with a range for.

[indiosmo]

Getting an out-of-bounds sequence access error when trying to iterate on the result of a set_symmetric_difference.
I'm using trunk.

#include "flux.hpp"
#include <iostream>
#include <cassert>

int main()
{
  std::array arr1{0, 1, 2, 3, 4, 5};
  std::array arr2{   1,    3,    5, 6, 7};
  auto merged = flux::set_symmetric_difference(flux::ref(arr1), flux::ref(arr2));

  assert(flux::equal(merged, std::array{0, 2, 4, 6, 7}));

  for (auto i : merged) {
    // crashes here
    std::cout << i << "\n";
  }

  return 0;
}

Link to the example: https://godbolt.org/z/z6E1eashz

I tried several variations, like reifying into a vector, also crashes

auto vec = merged.to<std::vector>(); // crashes

Interestingly I have a much more complex example using scan and map on the result of set_symmetric_difference and it works.
https://godbolt.org/z/9ex3se6hY

[tcbrindle]

Hi @indiosmo, thanks for the detailed bug report.

I think I can see what the problem is: set_symmetric_difference_adaptor's cursor_type should compare equal when both underlying cursors are the same; but the defaulted equality operator is also comparing the state_ field. This means that when using iterators, the end check never returns true and so iteration tries to run off the end of the underlying array, which (fortunately) gets caught by the bounds check.

[tcbrindle]

Hi @indiosmo, this should now be fixed. Thanks again for the bug report, please let me know if you come across any more problems

[indiosmo]

Cool, I'll test it in a few days. Thanks for the fix.