[Bug c++/91933] [8/9/10 Regression] ICE: tree check: expected class 'type', have 'exceptional' (error_mark) in build_simple_base_path, at cp/class.c:541

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91933

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
http://wg21.link/cwg696 looks relevant here.