Comment by johnisgood

And despite it being stuck at 5.1, it still implements features from other versions. For example, there is the "LJ_52" macro, so you can compile "table.pack" and "table.unpack" into LuaJIT, which I do, because I use both at times.

As someone else have pointed it out, they are cherry picked: https://luajit.org/extensions.html.