[Bug c++/83271] const variable previously declared "extern" results in "weak declaration must be public" error

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83271

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
At least there's a simple workaround (adding 'extern' to the definition where
the attribute).