[Bug c++/87425] [9 Regression] ICE with virtual assignment operator

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87425

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Jakub's patch <https://gcc.gnu.org/ml/gcc-patches/2018-09/msg01445.html> fixes
this, too, so I'll just add the new test.