https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61339
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to David Binderman from comment #5) > (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. Yes because clang added the warning to their compiler because they wanted to be compatible to MS's compiler.