https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61339
--- Comment #5 from David Binderman <dcb314 at hotmail dot com> --- (In reply to Jonathan Wakely from comment #1) > This is a really stupid warning that only exists because the MS compiler has > (or had) a bug that treats 'struct' and 'class' differently. GCC (and Clang) > correctly implement the C++ standard which says it doesn't matter. I can't speak for MS, but the original warning I posted was produced by clang. It *does* seem to worry about mismatched tags. Maybe someone could find out what newish versions of MS do with the code ?