[Bug c++/66996] [6 Regression] defined but not used [-Wunused-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66996

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The warning seems correct as Foo::~Foo is not used and the function can be used
outside of the current translation unit.