https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108619
--- Comment #8 from gccbugzilla at thepirate42 dot org --- The same code (with added rebind, https://godbolt.org/z/6fabvnvE7) compiles in c++17 mode, while in c++20 mode (also with added rebind, https://godbolt.org/z/ehhzYd5Wo) it doesn't, which means this is a bug right? I'm not an expert, but to my knowledge there shouldn't be any change in c++20 that makes this code ill formed.