In Loom 0.12 and Loader 0.14, an experimental option has been added to require all client code to be moved into its own sourceset: resources and common code will be in src/main, while client-only code will be in src/client.This provides a compile-time guarantee against calling client-only Minecraft code on the server. When building, Loom still produces a single jar that works on both the client and the server.