From 6ffb59200ef8a96a62d8eb3b35b2d4e650ae99eb Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Sun, 26 Apr 2026 17:46:39 +0200
Subject: [PATCH] Fixing issue #2339

Solution is to do proper cell mapping, including the parent
references from source to target RDB.
---
 src/rdb/rdb/rdb.cc             | 17 ++++++++++++++++-
 src/rdb/unit_tests/rdbTests.cc | 20 +++++++++++---------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/src/rdb/rdb/rdb.cc b/src/rdb/rdb/rdb.cc
index 475f310e4..367b25f5d 100644
--- a/src/rdb/rdb/rdb.cc
+++ b/src/rdb/rdb/rdb.cc
@@ -1920,13 +1920,15 @@ static void map_databases (rdb::Database &self, const rdb::Database &other,
                            std::map<id_type, id_type> &rev_tag2tag,
                            bool create_missing)
 {
+  std::list<std::pair<rdb::Cell *, const rdb::Cell *> > new_cells;
+
   for (auto c = other.cells ().begin (); c != other.cells ().end (); ++c) {
     //  TODO: do we have a consistent scheme of naming variants? What requirements
     //  exist towards detecting variant specific waivers
     rdb::Cell *this_cell = self.cell_by_qname_non_const (c->qname ());
     if (! this_cell && create_missing) {
       this_cell = self.create_cell (c->name (), c->variant (), c->layout_name ());
-      this_cell->import_references (c->references ());
+      new_cells.push_back (std::make_pair (this_cell, c.operator-> ()));
     }
     if (this_cell) {
       cell2cell.insert (std::make_pair (this_cell->id (), c->id ()));
@@ -1934,6 +1936,19 @@ static void map_databases (rdb::Database &self, const rdb::Database &other,
     }
   }
 
+  //  import and map references for new cells
+  for (auto cp = new_cells.begin (); cp != new_cells.end (); ++cp) {
+    auto &new_refs = cp->first->references ();
+    for (auto r = cp->second->references ().begin (); r != cp->second->references ().end (); ++r) {
+      rdb::Reference rnew = *r;
+      auto cid = rev_cell2cell.find (rnew.parent_cell_id ());
+      if (cid != rev_cell2cell.end ()) {
+        rnew.set_parent_cell_id (cid->second);
+        new_refs.insert (rnew);
+      }
+    }
+  }
+
   for (auto c = other.categories ().begin (); c != other.categories ().end (); ++c) {
     map_category (*c, self, cat2cat, rev_cat2cat, create_missing, 0);
   }
diff --git a/src/rdb/unit_tests/rdbTests.cc b/src/rdb/unit_tests/rdbTests.cc
index 4ccc25a08..814e73573 100644
--- a/src/rdb/unit_tests/rdbTests.cc
+++ b/src/rdb/unit_tests/rdbTests.cc
@@ -979,16 +979,18 @@ TEST(22_MergeCells)
   }
 
   {
+    rdb::Cell *cell1, *cell2, *cell3;
+    cell1 = db2.create_cell ("B");
+    cell2 = db2.create_cell ("A");
+    cell3 = db2.create_cell ("A", "VAR2", "ALAY");
+
+    //  NOTE: db2 parent is at a different position (issue #2339)
     rdb::Cell *parent;
     parent = db2.create_cell ("TOP");
 
-    rdb::Cell *cell;
-    cell = db2.create_cell ("B");
-    cell->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, 0.0)), parent->id ()));
-    cell = db2.create_cell ("A");
-    cell->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, 2.5)), parent->id ()));  //  reference not taken!
-    cell = db2.create_cell ("A", "VAR2", "ALAY");
-    cell->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, -1.0)), parent->id ()));
+    cell1->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, 0.0)), parent->id ()));
+    cell2->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, 2.5)), parent->id ()));  //  reference not taken as cell will be taken from db1
+    cell3->references ().insert (rdb::Reference (db::DCplxTrans (db::DVector (1.0, -1.0)), parent->id ()));
   }
 
   db1.merge (db2);
@@ -996,13 +998,13 @@ TEST(22_MergeCells)
   std::set<std::string> cells;
   for (auto c = db1.cells ().begin (); c != db1.cells ().end (); ++c) {
     if (c->references ().begin () != c->references ().end ()) {
-      cells.insert (c->qname () + "[" + c->references ().begin ()->trans_str () + "]");
+      cells.insert (c->qname () + "[" + c->references ().begin ()->trans_str () + ":" + db1.cell_by_id (c->references ().begin ()->parent_cell_id ())->qname () + "]");
     } else {
       cells.insert (c->qname ());
     }
   }
 
-  EXPECT_EQ (tl::join (cells.begin (), cells.end (), ";"), "A:1[r0 *1 1,2];A:VAR1[r0 *1 1,-2];A:VAR2[r0 *1 1,-1];B[r0 *1 1,0];TOP");
+  EXPECT_EQ (tl::join (cells.begin (), cells.end (), ";"), "A:1[r0 *1 1,2:TOP];A:VAR1[r0 *1 1,-2:TOP];A:VAR2[r0 *1 1,-1:TOP];B[r0 *1 1,0:TOP];TOP");
 }
 
 TEST(23_MergeTags)