https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96746
--- Comment #2 from Masamitsu MURASE <masamitsu.murase at gmail dot com> --- Thank you very much for your reply, Marek Polacek. I'm sorry, but I cannot understand your comment clearly. As you said, I also think that my example should be treated as ill-formed program. It **compiles fine** with GCC 11.0 even though it is ill-formed. It seems that clang and MSVC cause hard error appropriately. Regards, Murase