[Bug ipa/101813] New: -O3 does worse at constant folding than -O2

[nok.raven at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101813

            Bug ID: 101813
           Summary: -O3 does worse at constant folding than -O2
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nok.raven at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

#include <boost/optional.hpp>
#include <string>

using opts = boost::optional<std::string>;

struct foo
{
    foo(opts x) : b(x), c(x) {}

    opts a, b, c;
};

int main()
{
    opts a;

    foo bar(a);
}


at -O2 the example completely folds out, but not at -O3

https://godbolt.org/z/3n97aKKEh