[Bug libstdc++/91807] [9/10 Regression] std::variant with multiple identical types assignment fail to compile

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91807

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think this is probably due to the new std::variant implementation, not a
front-end bug. I just haven't had time to analyse it yet.