The variables G in globals.h and Ngbcnt and Ngblist in tree.h do not need to be defined in the headers as globals. I'm not exactly sure when this change was introduced to gcc's behaviour, but I can compile the existing version of WVTICs with ld version 2.27, but not with 2.35.2.
I've removed the variables G, Ngbcnt, and Ngblist from the headers globals.h and tree.h, since they don't need to be defined in multiple locations (G is only ever used locally, and Ngbcnt and Ngblist are never used at all).
The variables
Ginglobals.handNgbcntandNgblistintree.hdo not need to be defined in the headers as globals. I'm not exactly sure when this change was introduced to gcc's behaviour, but I can compile the existing version of WVTICs with ld version 2.27, but not with 2.35.2.I've removed the variables
G,Ngbcnt, andNgblistfrom the headersglobals.handtree.h, since they don't need to be defined in multiple locations (Gis only ever used locally, andNgbcntandNgblistare never used at all).