CLion

Buck (and therefore Buckaroo) can integrate with CLion via a compilation database.

If you want code completion for a target called //:app, then do:

buck build //:app#compilation-database --show-output

Buck probably put the file here (check the above command if your path differs):

cat buck-out/gen/__app#compilation-database/compile_commands.json

Then all you need to do is open the compile_commands.json file in CLion and you should be good to go.

More information regarding CLion's compilation database integration can be found in their documentation.