CC Mode: Fix positioning of point whilst inserting comments without non-ws

* lisp/progmodes/cc-cmds.el (c-guess-fill-prefix): When determining a new
block comment prefix (i.e. there isn't one already there to copy), and that
prefix is hard up against a comment closer, ensure there are at least two
spaces before the closer.
(c-indent-new-comment-line): Amend the strategy for ensuring that point isn't
left hard up against the comment closer after M-j.

1 files changed, 18 insertions, 9 deletions

diff --git a/lisp/progmodes/cc-cmds.el b/lisp/progmodes/cc-cmds.el
index 0d9414e60fb..9aa2019ae60 100644
--- a/lisp/progmodes/cc-cmds.el
+++ b/lisp/progmodes/cc-cmds.el
@@ -4083,14 +4083,18 @@ command to conveniently insert and align the necessary backslashes."
             ;; `comment-prefix' on a line and indent it to find the
             ;; correct column and the correct mix of tabs and spaces.
             (setq res
-                  (let (tmp-pre tmp-post)
+                  (let (tmp-pre tmp-post at-close)
                     (unwind-protect
                         (progn
 
                           (goto-char (car lit-limits))
                           (if (looking-at comment-start-regexp)
-                              (goto-char (min (match-end 0)
-                                              comment-text-end))
+                              (progn
+                                (goto-char (min (match-end 0)
+                                                comment-text-end))
+                                (setq
+                                 at-close
+                                 (looking-at c-block-comment-ender-regexp)))
                             (forward-char 2)
                             (skip-chars-forward " \t"))
 
@@ -4106,8 +4110,13 @@ command to conveniently insert and align the necessary backslashes."
                                            (save-excursion
                                              (skip-chars-backward " \t")
                                              (point))
-                                           (point)))))
-
+                                           (point))))
+                            ;; If hard up against the comment ender, the
+                            ;; prefix must end in at least two spaces.
+                            (when at-close
+                              (or (string-match "\\s \\s +\\'" comment-prefix)
+                                  (setq comment-prefix
+                                        (concat comment-prefix " ")))))
                           (setq tmp-pre (point-marker))
 
                           ;; We insert an extra non-whitespace character
@@ -4776,7 +4785,6 @@ If a fill prefix is specified, it overrides all the above."
                                     (c-collect-line-comments c-lit-limits))
                               c-lit-type)))
                      (pos (point))
-                     (start-col (current-column))
                      (comment-text-end
                       (or (and (eq c-lit-type 'c)
                                (save-excursion
@@ -4821,9 +4829,10 @@ If a fill prefix is specified, it overrides all the above."
                           (goto-char (+ (car c-lit-limits) 2))))
                    (funcall do-line-break)
                    (insert-and-inherit (car fill))
-                   (if (> (current-column) start-col)
-                       (move-to-column start-col)))) ; can this hit the
-                                                     ; middle of a TAB?
+                   (if (and (looking-at c-block-comment-ender-regexp)
+                            (memq (char-before) '(?\  ?\t)))
+                       (backward-char)))) ; can this hit the
+                                          ; middle of a TAB?
              ;; Inside a comment that should be broken.
              (let ((comment-start comment-start)
                    (comment-end comment-end)