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, 5 insertions, 3 deletions

diff --git a/src/eval.c b/src/eval.c
index 959adea6467..9daae92e55a 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -831,6 +831,7 @@ usage: (defconst SYMBOL INITVALUE [DOCSTRING])  */)
   Lisp_Object sym, tem;
 
   sym = XCAR (args);
+  CHECK_SYMBOL (sym);
   Lisp_Object docstring = Qnil;
   if (!NILP (XCDR (XCDR (args))))
     {
diff --git a/src/xdisp.c b/src/xdisp.c
index bd0711471a2..e454fd7b83f 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1871,9 +1871,10 @@ pos_visible_p (struct window *w, ptrdiff_t charpos, int *x, int *y,
                   top_x = it3.current_x - it3.pixel_width;
                   /* Account for line-number display, if IT3 still
                      didn't.  This can happen if START - 1 is the
-                     first character on its display line.  */
-                  if (!it3.line_number_produced_p
-                      && it.line_number_produced_p)
+                     first or the last character on its display line.  */
+                  if (it3.lnum_pixel_width > 0)
+                    top_x += it3.lnum_pixel_width;
+                  else if (it.line_number_produced_p)
                     top_x += it.lnum_pixel_width;
                   /* Normally, we would exit the above loop because we
                      found the display element whose character