Yet another fix for copying properties by 'format'

* src/textprop.c (extend_property_ranges): Accept an additional
argument OLD_END, and only extend the end of a property range if
its original end is at OLD_END; all the other ranges are left
intact.  (Bug#23897)
* src/editfns.c (styled_format): Pass the original length of the
string to 'extend_property_ranges'.
* src/intervals.h (extend_property_ranges): Adjust prototype.

* test/src/editfns-tests.el (format-properties): Add tests for
bug#23897.

4 files changed, 21 insertions, 8 deletions

diff --git a/src/editfns.c b/src/editfns.c
index 0c01c748d22..73f024409b1 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -4631,7 +4631,7 @@ styled_format (ptrdiff_t nargs, Lisp_Object *args, bool message)
               len = make_number (SCHARS (args[i]));
               Lisp_Object new_len = make_number (info[i].end - info[i].start);
               props = text_property_list (args[i], make_number (0), len, Qnil);
-              props = extend_property_ranges (props, new_len);
+              props = extend_property_ranges (props, len, new_len);
               /* If successive arguments have properties, be sure that
                  the value of `composition' property be the copy.  */
               if (1 < i && info[i - 1].end)
diff --git a/src/intervals.h b/src/intervals.h
index 6a5a4129abc..9a38d849b88 100644
--- a/src/intervals.h
+++ b/src/intervals.h
@@ -285,7 +285,7 @@ extern void set_text_properties_1 (Lisp_Object, Lisp_Object,
 Lisp_Object text_property_list (Lisp_Object, Lisp_Object, Lisp_Object,
                                 Lisp_Object);
 void add_text_properties_from_list (Lisp_Object, Lisp_Object, Lisp_Object);
-Lisp_Object extend_property_ranges (Lisp_Object, Lisp_Object);
+Lisp_Object extend_property_ranges (Lisp_Object, Lisp_Object, Lisp_Object);
 Lisp_Object get_char_property_and_overlay (Lisp_Object, Lisp_Object,
                                            Lisp_Object, Lisp_Object*);
 extern int text_property_stickiness (Lisp_Object prop, Lisp_Object pos,
diff --git a/src/textprop.c b/src/textprop.c
index aabd5671e76..7af8c698736 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -2043,18 +2043,19 @@ add_text_properties_from_list (Lisp_Object object, Lisp_Object list, Lisp_Object
    end-points to NEW_END.  */
 
 Lisp_Object
-extend_property_ranges (Lisp_Object list, Lisp_Object new_end)
+extend_property_ranges (Lisp_Object list, Lisp_Object old_end, Lisp_Object new_end)
 {
   Lisp_Object prev = Qnil, head = list;
   ptrdiff_t max = XINT (new_end);
 
   for (; CONSP (list); prev = list, list = XCDR (list))
     {
-      Lisp_Object item, beg, end;
+      Lisp_Object item, beg;
+      ptrdiff_t end;
 
       item = XCAR (list);
       beg = XCAR (item);
-      end = XCAR (XCDR (item));
+      end = XINT (XCAR (XCDR (item)));
 
       if (XINT (beg) >= max)
         {
@@ -2065,12 +2066,14 @@ extend_property_ranges (Lisp_Object list, Lisp_Object new_end)
           else
             XSETCDR (prev, XCDR (list));
         }
-      else if (XINT (end) != max)
+      else if ((end == XINT (old_end) && end != max)
+               || end > max)
         {
           /* Either the end-point is past the end of the new string,
              and we need to discard the properties past the new end,
              or the caller is extending the property range, and we
-             should update the end-point to reflect that.  */
+             should update all end-points that are on the old end of
+             the range to reflect that.  */
           XSETCAR (XCDR (item), new_end);
         }
     }
diff --git a/test/src/editfns-tests.el b/test/src/editfns-tests.el
index c515927cff1..62d7bc4f5be 100644
--- a/test/src/editfns-tests.el
+++ b/test/src/editfns-tests.el
@@ -54,4 +54,14 @@
   ;; Bug #23859
   (should (ert-equal-including-properties
            (format "%4s" (propertize "hi" 'face 'bold))
-           #("  hi" 0 4 (face bold)))))
+           #("  hi" 0 4 (face bold))))
+
+  ;; Bug #23897
+  (should (ert-equal-including-properties
+           (format "%s" (concat (propertize "01234" 'face 'bold) "56789"))
+           #("0123456789" 0 5 (face bold))))
+  (should (ert-equal-including-properties
+           (format "%s" (concat (propertize "01" 'face 'bold)
+                                (propertize "23" 'face 'underline)
+                                "45"))
+           #("012345" 0 2 (face bold) 2 4 (face underline)))))