bug#6556: html-mode does not align to prev non-empty line when indenting

[Lennart Borgman]

In a buffer like this

   <p>
      row 1
         row 2
     row 3

the "row 3" gets indented like above. I think it instead should be
aligned with row2. (I need this for mumamo.)

The comment in sgml-calculate-indent seems to say that this is the
intention, but the code is maybe unfinished, line 1483:

            (context
             ;; If possible, align on the previous non-empty text line.
             ;; Otherwise, do a more serious parsing to find the
             ;; tag(s) relative to which we should be indenting.
             (if (and (not unclosed) (skip-chars-backward " \t")
                      (< (skip-chars-backward " \t\n") 0)
                      (back-to-indentation)
                      (> (point) (cdr lcon)))
                 nil
               (goto-char here)
               (nreverse (sgml-get-context (if unclosed nil 'empty)))))

I do not know how it is supposed to work, but I notice that
(back-to-indentation) is not supposed to return anything special so
the argument to if may fail (and this seems to happen). Writing that
part as


                    (progn
                      (back-to-indentation)
                      (> (point) (cdr lcon))))


seems to work as expected.