old_pointer definition

[skyelves]

ROART/ART/N.cpp

Line 932 in c313e0f

node->old_pointer.store(0);

I am trying to reproduce the results of the ROART and when I try to compile the source code, an error occurs
error: no member named 'old_pointer' in 'N' node->old_pointer.store(0);
When I grep in the codebase, I also can not find the definition of the old_pointer.