SORT VARIABLES: Improve stability of sort.

[pspp] / src / language / dictionary / sort-variables.c

diff --git a/src/language/dictionary/sort-variables.c b/src/language/dictionary/sort-variables.c
index 8c653af7248c1cf8470009e06d7c53dba483a129..aee341bda61770f633964c1ab493960c0366ed4a 100644 (file)
--- a/src/language/dictionary/sort-variables.c
+++ b/src/language/dictionary/sort-variables.c
@@ -190,7 +190,11 @@ compare_vars (const void *a_, const void *b_, const void *c_)
 
   /* Make this a stable sort. */
   if (!retval)
-    retval = a < b ? -1 : a > b;
+    {
+      size_t a_index = var_get_dict_index (a);
+      size_t b_index = var_get_dict_index (b);
+      retval = a_index < b_index ? -1 : a_index > b_index;
+    }
 
   if (c->descending)
     retval = -retval;