https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83503
--- Comment #12 from Martin Sebor <msebor at gcc dot gnu.org> --- AFAIK, specifying attribute const and pure on a function definition has no effect on the code emitted for the function itself or on its callers in other translation units, so what you describe doesn't sound meaningful. It's fine, though pointless, to declare a function pure and define it so that it meets stricter requirements under some conditions, just as long as the attributes don't clash.
