comment-normalize-vars is a compiled Lisp function in `newcomment.el'.

(comment-normalize-vars &optional NOERROR)

Check and set up variables needed by other commenting functions.
All the `comment-*' commands call this function to set up various
variables, like `comment-start', to ensure that the commenting
functions work correctly. Lisp callers of any other `comment-*'
function should first call this function explicitly.