[Bug c++/60347] [4.9 Regression] r208153 breaks Firefox build

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60347

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
I did add a testcase, which is not significantly different from the one in
comment #3.