[Bug libstdc++/79156] incorrect c++ usage in gcc7 void function returns a value

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79156

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|NEW                         |RESOLVED
            Version|unknown                     |7.0
         Resolution|---                         |FIXED
   Target Milestone|---                         |7.0

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It is meant to return __p, so I fixed the return type. There was also a friend
declaration missing.