[Bug sanitizer/64670] -fsanitize=vptr leads to "undefined reference to `typeinfo for class'"

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64670

--- Comment #11 from Tobias Burnus <burnus at gcc dot gnu.org> ---
(In reply to Jason Merrill from comment #10)
> Having #pragma implementation in LogListener.cc is sufficient:
> > The real-world LogListener.o has (full output as it is short):
> ...
> > 0000000000000000 V typeinfo for LogListener
> So why are you getting an undefined reference?

Because log.o has due to the vptr sanitizer:
                 U typeinfo for LogListener