From 1d0aef7d0b5448be980a3c51ef9fd04b5a0ab339 Mon Sep 17 00:00:00 2001
From: Donald Buczek <buczek@molgen.mpg.de>
Date: Sun, 20 Mar 2022 10:38:25 +0100
Subject: [PATCH] mx_util: Mention stable sort property in comments

_mx_sort_linked_list and its macro wrapper mx_sort_linked_list currently
do a stable sort. Add comments to the code and the test that this is
guaranteed behaviour, because we are going to depend on it in the
following commits.
---
 mx_util.c      | 1 +
 test_mx_util.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/mx_util.c b/mx_util.c
index 8b675159..0aea3183 100644
--- a/mx_util.c
+++ b/mx_util.c
@@ -1268,6 +1268,7 @@ int mx_daemon(int nochdir, int noclose)
     return daemon(nochdir, noclose);
 }
 
+/* guarantee stable sort */
 void _mx_sort_linked_list (void **list,  int (*cmp)(void *o1,void *o2), void ** getnextptr(void *o)) {
 
     void *unsorted=*list;
diff --git a/test_mx_util.c b/test_mx_util.c
index 6f473093..20b58c81 100644
--- a/test_mx_util.c
+++ b/test_mx_util.c
@@ -489,6 +489,7 @@ static void test_listsort(void)
     }
 
     /* (100 0 1 2 50 50 2 1 0 100)  -> ( 0 0 1 1 2 2 50 50 100 100) stable */
+    /* also verify stable sort */
     for (int i=0;i<10;i++) {
         o[i].next= i==9 ? NULL : &o[i+1];
     }