cjson-2.1.0.6-1 has a bug that prevents it from working with lua >= 5.2:

• https://stackoverflow.com/questions/50281201/symbol-not-found-lua-objlen
• Symbol not found: _lua_objlen mpx/lua-cjson#56
• Won't built against Lua >= 5.2 openresty/lua-cjson#36

Note that this is a runtime error and is not caught in the process of building the package. (We can add a simple lua -e "require 'cjson'" in the checkPhase to catch this in the future.)

I haven't found a patch we could apply, so I think we should either 1) mark the package as broken for lua >= 5.2, too, or 2) downgrade the package to 2.1.0-1. (I prefer the downgrade.)

one can set a PR that pins the version by setting the version in the appropriate column of the csv file maintainers/scripts/luarocks-packages.csv .
luarocks 3 introduced better support for testing so ideally lua-cjson would update their rockspec to launch their testsuite (should be easy since they already have a testsuite).

I had started some work in luarocks-nix towards better support of checkPhase and all but lacked time and a good example. This could be it.