From a8781515e5241b405139c904fb5875108344a5c0 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 26 Apr 2013 14:41:59 +0200
Subject: Fix bug in diff'ing models of same version

---
 odb/relational/changelog.cxx | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

(limited to 'odb')

diff --git a/odb/relational/changelog.cxx b/odb/relational/changelog.cxx
index 585a2c4..af1dcea 100644
--- a/odb/relational/changelog.cxx
+++ b/odb/relational/changelog.cxx
@@ -412,12 +412,27 @@ namespace relational
       {
         changeset& r (l.new_node<changeset> (n.version ()));
 
-        // Set the alters edge for lookup.
+        // Set the alters edge for lookup. If we are diff'ing two models of
+        // the same version, then use the old model as a base. Otherwise use
+        // the tip of changelog (it should correspond to the old model).
         //
-        l.new_edge<alters> (r,
-                            l.contains_changeset_empty ()
-                            ? static_cast<qscope&> (l.model ())
-                            : l.contains_changeset_back ().changeset ());
+        if (o.version () == n.version ())
+          l.new_edge<alters> (r, o);
+        else
+        {
+          if (l.contains_changeset_empty ())
+          {
+            model& m (l.model ());
+            assert (o.version () == m.version ());
+            l.new_edge<alters> (r, m);
+          }
+          else
+          {
+            changeset& c (l.contains_changeset_back ().changeset ());
+            assert (o.version () == c.version ());
+            l.new_edge<alters> (r, c);
+          }
+        }
 
         {
           trav_rel::model model;
-- 
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