From c17753766956d1c904150065f052800000195881 Mon Sep 17 00:00:00 2001
From: Werner Lemberg <wl@gnu.org>
Date: Sun, 22 Oct 2017 08:51:43 +0200
Subject: [PATCH] [numberset] Make `number_set_insert' completely merge
 adjacent ranges.

---
 lib/numberset.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/lib/numberset.c b/lib/numberset.c
index deea097..dc916c6 100644
--- a/lib/numberset.c
+++ b/lib/numberset.c
@@ -124,26 +124,35 @@ number_set_insert(number_range* list,
       return NUMBERSET_OVERLAPPING_RANGES;
 
     /* merge adjacent ranges */
-    if (element->start == nr->end + 1)
-    {
-      nr->end = element->end;
-
-      free(element);
-
-      return list;
-    }
     if (element->end + 1 == nr->start)
     {
       nr->start = element->start;
 
       free(element);
 
+      if (nr->next
+          && nr->next->end + 1 == nr->start)
+      {
+        element = nr->next;
+        element->end = nr->end;
+        free(nr);
+        return element;
+      }
+
       return list;
     }
 
     /* insert element */
     if (element->start > nr->end)
     {
+      /* merge adjacent ranges */
+      if (nr->end + 1 == element->start)
+      {
+        nr->end = element->end;
+        free(element);
+        return list;
+      }
+
       if (prev)
         prev->next = element;
       element->next = nr;
@@ -155,7 +164,7 @@ number_set_insert(number_range* list,
     nr = nr->next;
   }
 
-  /* append element */
+  /* prepend element */
   prev->next = element;
   element->next = NULL;
 
-- 
2.11.4.GIT