There already exist such tools, and especially now with go-generate in 1.4 it's become easier to do that. But we need deeper integration for them, like gocode c

There already exist such tools, and especially now with go-generate in 1.4 it's become easier to do that. But we need deeper integration for them, like gocode completion being able to work on the generic files, linters that can lint a template based source file, etc. If a holistic approach like that would exist I'd personally use a preprocessor.