* lisp/newcomment.el (comment-indent-new-line): Sink code where it's used.

Reuse the previous comment's indentation unconditionally if it's on its
own line.

2 files changed, 41 insertions, 22 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index bab1edaffda..e5761ced42b 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2014-04-11  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * newcomment.el (comment-indent-new-line): Sink code where it's used.
+        Reuse the previous comment's indentation unconditionally if it's on its
+        own line.
+
 2014-04-09  Daniel Colascione  <dancol@dancol.org>
 
         * emacs-lisp/lisp.el (backward-up-list): Add `escape-strings',
diff --git a/lisp/newcomment.el b/lisp/newcomment.el
index 2d798494b8b..b607eb95df2 100644
--- a/lisp/newcomment.el
+++ b/lisp/newcomment.el
@@ -1390,22 +1390,12 @@ unless optional argument SOFT is non-nil."
          ;; If we're not inside a comment, just try to indent.
          ((not compos) (indent-according-to-mode))
          (t
-          (let* ((comment-column
-                  ;; The continuation indentation should be somewhere between
-                  ;; the current line's indentation (plus 2 for good measure)
-                  ;; and the current comment's indentation, with a preference
-                  ;; for comment-column.
-                  (save-excursion
-                    ;; FIXME: use prev line's info rather than first line's.
-                    (goto-char compos)
-                    (min (current-column) (max comment-column
-                                               (+ 2 (current-indentation))))))
-                 (comstart (buffer-substring compos comin))
+          (let* ((comstart (buffer-substring compos comin))
                  (normalp
                   (string-match (regexp-quote (comment-string-strip
                                                comment-start t t))
                                 comstart))
-                 (comment-end
+                 (comend
                   (if normalp comment-end
                     ;; The comment starter is not the normal comment-start
                     ;; so we can't just use comment-end.
@@ -1416,19 +1406,42 @@ unless optional argument SOFT is non-nil."
                          (buffer-substring
                           (save-excursion (comment-enter-backward) (point))
                           (point))
-                         nil t)))))
-                 (comment-start comstart)
-                 (continuep (or comment-multi-line
-                                (cadr (assoc comment-style comment-styles))))
-                 ;; Force comment-continue to be recreated from comment-start.
-                 ;; FIXME: wrong if comment-continue was set explicitly!
-                 ;; FIXME: use prev line's continuation if available.
-                 (comment-continue nil))
-            (if (and comment-multi-line (> (length comment-end) 0))
+                         nil t))))))
+            (if (and comment-multi-line (> (length comend) 0))
                 (indent-according-to-mode)
               (insert-and-inherit ?\n)
               (forward-char -1)
-              (comment-indent continuep)
+              (let* ((comment-column
+                      ;; The continuation indentation should be somewhere
+                      ;; between the current line's indentation (plus 2 for
+                      ;; good measure) and the current comment's indentation,
+                      ;; with a preference for comment-column.
+                      (save-excursion
+                        ;; FIXME: use prev line's info rather than first
+                        ;; line's.
+                        (goto-char compos)
+                        (min (current-column)
+                             (max comment-column
+                                  (+ 2 (current-indentation))))))
+                     (comment-indent-function
+                      ;; If the previous comment is on its own line, then
+                      ;; reuse its indentation unconditionally.
+                      ;; Important for modes like Python/Haskell where
+                      ;; auto-indentation is unreliable.
+                      (if (save-excursion (goto-char compos)
+                                          (skip-chars-backward " \t")
+                                          (bolp))
+                          (lambda () comment-column) comment-indent-function))
+                     (comment-start comstart)
+                     (comment-end comend)
+                     (continuep (or comment-multi-line
+                                    (cadr (assoc comment-style
+                                                 comment-styles))))
+                     ;; Recreate comment-continue from comment-start.
+                     ;; FIXME: wrong if comment-continue was set explicitly!
+                     ;; FIXME: use prev line's continuation if available.
+                     (comment-continue nil))
+                (comment-indent continuep))
               (save-excursion
                 (let ((pt (point)))
                   (end-of-line)