[Bug c++/89315] [9 Regression] Cannot convert to std::initializer_list - fails with gcc9 works with gcc8

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89315

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed by r268969, will add the test.