[Bug c++/92431] ICE with spaceship in constexpr evaluation

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92431

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Slightly further reduced:

#include <compare>

constexpr std::weak_ordering
cmp(int e, int f)
{
  return e <=> f;
}

auto o = cmp(1, 2);