Set comments at the same indentation level as all forms

Question

By default, comments get an indentation level which seems rather alien to me.

(defun example ()
  just
  some
                ; a comment
  words)

How to adjust it so the first semicolon is vertically aligned with the regular Lisp forms?

(defun example ()
  just
  some
  ; a comment
  words)

What I could find out is that the default mechanism works by aligning the comments to a fixed column (queryable via M-x comment-set-column), and that one can modify the comment-indent-function variable (setting it to nil partially fixes my problem).

Answer 1

Emacs indents comments in elisp differently depending on the number of semicolons used. If you use two, you should get the indentation you're after:

(defun test-single ()
                                        ; A single semicolon
  nil)

(defun test-double ()
  ;; Do two semicolons make a colon ;)
  nil)

In addition, three semicolons ;;; are not re-indented at all. Typically, they are used to mark new major sections in the source file.