https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71784
--- Comment #8 from Ela <mct_ancs at yahoo dot com> --- (In reply to Martin Liška from comment #7) > Same as the origin, it's obviously an invalid code. Tested on all Clang-3.8 C++11,14,17 - it works. gcc-6.1.0 is a bit more explicit in some sense: - class instantiation w/ external leaves all members non-inst. - the missing function in the call (in main() ) is written as some mangle, and not in_clear (as it would be with other functions - that one can add for test) - thus seems as a lack of internal repres. or something. Else please enlighten me on the correct syntax.