[Bug c++/71143] [7 Regression] bogus error: ‘A’ is not a base of ‘B< >’

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71143

--- Comment #1 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Started with r236221.