IMO newlines are often used like paragraphs in a book, they separate distinct ideas. How would you suggest this fragment be formatted?

err := fn()
if err != nil { 
   // clean up
   return err
}

I agree that go fmt should enforce some newlines, I'm not sure I agree with the rules you came up with, as this would mean that simple error checks have a new line before them.

• newline after a block ({}\n) or multiple continious blocks (if {} else{}\n), this means a newline after every error check

• the newline isn't added if the following line also closes a block

func main() {
    for {
    } // no newline here
}

There might be other cases where it makes sense to inject a newline.

I think this is highly opinonated and we should explore this with gofumpt first.

Please see https://github.com/golang/go/wiki/Questions. Closing.