[Bug c++/90858] Pointer to member is treated as non-constexpr

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90858

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Not quite sure if that is a backportable change.  Maybe if we knew what exactly
in that commit made the difference.