From da38ae03707902a3104745f23121297fb65540be Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Tue, 23 Oct 2018 08:57:33 -0400
Subject: [PATCH] apply fix for merge sort from issue #1163 by @jtfrey and
 re-enable it

---
 src/lmptype.h   | 7 -------
 src/mergesort.h | 6 +++++-
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/lmptype.h b/src/lmptype.h
index 7c3dbc1c3d..4743a38837 100644
--- a/src/lmptype.h
+++ b/src/lmptype.h
@@ -46,13 +46,6 @@
 #define PRId64 "ld"
 #endif
 
-// favor qsort over mergesort for stable release
-// TODO: to be removed after stable release
-
-#ifndef LMP_QSORT
-#define LMP_QSORT
-#endif
-
 namespace LAMMPS_NS {
 
 // enum used for KOKKOS host/device flags
diff --git a/src/mergesort.h b/src/mergesort.h
index 50addd0a72..edb745922f 100644
--- a/src/mergesort.h
+++ b/src/mergesort.h
@@ -98,7 +98,7 @@ static void merge_sort(int *index, int num, void *ptr,
 
     int *tmp = dest; dest = hold; hold = tmp;
 
-    // merge from hold array to destiation array
+    // merge from hold array to destination array
 
     for (i=0; i < num-1; i += 2*chunk) {
       j = i + 2*chunk;
@@ -107,6 +107,10 @@ static void merge_sort(int *index, int num, void *ptr,
       if (m > num) m=num;
       do_merge(dest,hold,i,m,m,j,ptr,comp);
     }
+
+    // copy all indices not handled by the chunked merge sort loop
+
+    for ( ; i < num ; i++ ) dest[i] = hold[i];
     chunk *= 2;
   }