[Bug c++/106199] New: vector::insert optimization is broken with gcc-12

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106199

            Bug ID: 106199
           Summary: vector::insert optimization is broken with gcc-12
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

Example from
https://stackoverflow.com/questions/72867072/why-g12-vector-insert-optimization-breaks-code

#include <vector>
#include <array>

std::vector<int> s_to_bytes() {
  std::vector<int> res;
  std::array<int, 4> s{};
  res.insert(res.begin(), s.begin(), s.end());
  return res;
}

https://godbolt.org/z/4YrzTso9o