https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117810
--- Comment #3 from uecker at gcc dot gnu.org --- Not sure what this has to do with constexpr, but allowing expressions should be possible. WG21 is working on contracts to specify pre-. and postprocessing, but I am not sure advanced this is. I suggested an attribute for data structures that would take expressions: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116194
