Merge from origin/emacs-27

5280e118c0 (origin/emacs-27) ; * src/xdisp.c (pos_visible_p): Fix las...
bb1a9481c9 Fix posn-at-point at beginning of a display string
0c4b033670 Improve documentation of Info node movement commands
632b0119e1 Add Jansson dependency to Windows Build
dbfcdab837 Unbreak 'reverse-region'
c37de84845 Fix typos and markup in fill column indicator docs
f61bff3ee9 ; * CONTRIBUTE: Clarify the preferences for patch formatting.
368e140660 Avoid crashes in 'defconst'
11e3413cff Fix text about Lisp archives in the Emacs FQ
4c81724675 Don't use 'cl' functions in ELisp manual's examples

2 files changed, 16 insertions, 7 deletions

diff --git a/lisp/info.el b/lisp/info.el
index d579ecc5a3b..78f88947c79 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -2265,7 +2265,8 @@ End of submatch 0, 1, and 3 are the same, so you can safely concat."
        (match-string-no-properties 1)))
 
 (defun Info-next ()
-  "Go to the next node of this node."
+  "Go to the \"next\" node, staying on the same hierarchical level.
+This command doesn't descend into sub-nodes, like \\<Info-mode-map>\\[Info-forward-node] does."
   (interactive)
   ;; In case another window is currently selected
   (save-window-excursion
@@ -2273,7 +2274,8 @@ End of submatch 0, 1, and 3 are the same, so you can safely concat."
     (Info-goto-node (Info-extract-pointer "next"))))
 
 (defun Info-prev ()
-  "Go to the previous node of this node."
+  "Go to the \"previous\" node, staying on the same hierarchical level.
+This command doesn't go up to the parent node, like \\<Info-mode-map>\\[Info-backward-node] does."
   (interactive)
   ;; In case another window is currently selected
   (save-window-excursion
@@ -2887,7 +2889,13 @@ N is the digit argument used to invoke this command."
       (Info-goto-node (Info-extract-menu-counting nil)))))
 
 (defun Info-forward-node (&optional not-down not-up no-error)
-  "Go forward one node, considering all nodes as forming one sequence."
+  "Go forward one node, considering all nodes as forming one sequence.
+Interactively, if the current node has sub-nodes, descend into the first
+sub-node; otherwise go to the \"next\" node, if it exists, else go \"up\"
+to the parent node.
+When called from Lisp, NOT-DOWN non-nil means don't descend into sub-nodes,
+NOT-UP non-nil means don't go to parent nodes, and NO-ERROR non-nil means
+don't signal a user-error if there's no node to go to."
   (interactive)
   (goto-char (point-min))
   (forward-line 1)
@@ -2922,7 +2930,9 @@ N is the digit argument used to invoke this command."
           (t (user-error "No pointer forward from this node")))))
 
 (defun Info-backward-node ()
-  "Go backward one node, considering all nodes as forming one sequence."
+  "Go backward one node, considering all nodes as forming one sequence.
+If the current node has a \"previous\" node, go to it, descending into its
+last sub-node, if any; otherwise go \"up\" to the parent node."
   (interactive)
   (let ((prevnode (Info-extract-pointer "prev[ious]*" t))
         (upnode (Info-extract-pointer "up" t))
diff --git a/lisp/sort.el b/lisp/sort.el
index de0e1b9519d..f878db24a3c 100644
--- a/lisp/sort.el
+++ b/lisp/sort.el
@@ -554,9 +554,6 @@ is the one that ends before END."
   (if (> beg end)
       (let (mid) (setq mid end end beg beg mid)))
   (save-excursion
-    (when (or (< (line-beginning-position) beg)
-              (< end (line-end-position)))
-      (user-error "There are no full lines in the region"))
     ;; Put beg at the start of a line and end and the end of one --
     ;; the largest possible region which fits this criteria.
     (goto-char beg)
@@ -568,6 +565,8 @@ is the one that ends before END."
     ;; reversal; it isn't difficult to add it afterward.
     (or (and (eolp) (not (bolp))) (progn (forward-line -1) (end-of-line)))
     (setq end (point-marker))
+    (when (<= end beg)
+      (user-error "There are no full lines in the region"))
     ;; The real work.  This thing cranks through memory on large regions.
     (let (ll (do t))
       (while do