Confusing GCC on aarch64

[iazz]

The following code compiles just fine, but on aarch64, with -O2, with a recent GCC (at least from version 11 and until the very tip of the master branch), the last assert fails:

#include <cassert>
#include <boost/bimap.hpp>
#include <boost/bimap/unordered_set_of.hpp>

int main()
{
  using map_type = boost::bimap<boost::bimaps::set_of<int>,
				boost::bimaps::unordered_set_of<int>>;
  map_type	map;
  auto	x = map.insert({0, 0}).first;
  map.replace_right(x, 42);
  auto	y = map.find(map_type::value_type{0, 42});
  assert(y != map.end());
  assert(x == y);
  assert(&x->right == &y->right);
  assert(y->right != 0);
  assert(x->right != 0);
}

With -O2 -fno-strict-aliasing, or with -O1 or -O0, all the asserts pass.

I've filed a bug in GCC (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115767), but I'm afraid this can be a bug in Boost Bimap instead. At least it would be very beneficial to further reduce this code to its absolute minimum, so I'm asking for help the library authors.

Thanks.