https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65890
--- Comment #1 from frankhb1989 at gmail dot com --- Oops, wrong version of case pasted ... I once wanted to use this minimal one: sizeof(Tag::m); Nevertheless, the conclusion is the same for this issue. (There are other mess, e.g. Clang++ 3.6 wrongly interpret 'decltype(&(Tag::m))' as pointer to member but I think G++ is right here).