https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70248
--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> --- Rejecting the test case because of the initialization is a regression. The cast is not a reinterpret cast. GCC gives the same error with a static cast too: $ gcc -S -Wall pr70248.C pr70248.C:4:24: error: a reinterpret_cast is not a constant expression constexpr int A::*bx = static_cast<int(A::*)>(&B::x); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ pr70248.C:5:24: error: a reinterpret_cast is not a constant expression constexpr int A::*cx = static_cast<int(A::*)>(&C::x); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~