https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102015
--- Comment #2 from Kamil Kaznowski <kamkaz at windowslive dot com> --- (In reply to Andrew Pinski from comment #1) > https://stackoverflow.com/questions/66573773/is-there-a-reason-for-8-bytes- > of-size-overhead-in-libstdc-stdmultiset-map This is my post, I forgot to post a bug that day. There is also a mistake by me in the comments - MSVC _Compressed_pair works by template specialization, not SFINAE.