Merge pull request #1842 from KLayout/bugfix/issue-1835

Bugfix/issue 1835

src/db/db/dbCommonReader.cc

@@ -23,6 +23,7 @@
 
 
 #include "dbCommonReader.h"
+#include "dbColdProxy.h"
 #include "dbStream.h"
 #include "tlXMLParser.h"
 
@@ -475,7 +476,7 @@ CommonReaderBase::finish (db::Layout &layout)
     }
 
     if (name) {
-      //  need to rename: add a new madding to m_layer_map_out and adjust the layout's layer properties
+      //  need to rename: add a new mapping to m_layer_map_out and adjust the layout's layer properties
       db::LayerProperties lpp = lp;
       join_layer_names (lpp.name, *name);
       layout.set_properties (*i, lpp);
@@ -580,9 +581,32 @@ CommonReader::read (db::Layout &layout, const db::LoadLayoutOptions &options)
   }
 
   //  A cleanup may be necessary because of the following scenario: if library proxies contain subcells
-  //  which are proxies itself, the proxy update may make them orphans (the proxies are regenerated).
+  //  which are proxies themselves, the proxy update may make them orphans (the proxies are regenerated).
   //  The cleanup will removed these.
-  layout.cleanup ();
+
+  //  Adressing issue #1835 (reading proxy-only GDS file renders empty layout) we do not delete
+  //  the first (non-cold) proxy if there are only proxy top cells.
+  //  We never clean up the top cell if there is a single one. This catches the case of having
+  //  defunct proxies for top cells.
+
+  std::set<db::cell_index_type> keep;
+  if (layout.end_top_cells () - layout.begin_top_down () == 1) {
+    keep.insert (*layout.begin_top_down ());
+  } else {
+    for (auto c = layout.begin_top_down (); c != layout.end_top_cells (); ++c) {
+      const db::Cell *cptr = &layout.cell (*c);
+      if (cptr->is_proxy ()) {
+        if (! dynamic_cast <const db::ColdProxy *> (cptr) && keep.empty ()) {
+          keep.insert (*c);
+        }
+      } else {
+        keep.clear ();
+        break;
+      }
+    }
+  }
+
+  layout.cleanup (keep);
 
   return layer_map_out ();
 }

src/layui/layui/layLayoutViewFunctions.cc

@@ -1230,11 +1230,12 @@ LayoutViewFunctions::do_cm_paste (bool interactive)
 void
 LayoutViewFunctions::cm_new_cell ()
 {
-  lay::CellView cv = view ()->cellview (view ()->active_cellview_index ());
-  if (! cv.is_valid ()) {
+  if (view ()->active_cellview_index () < 0) {
     throw tl::Exception (tl::to_string (tr ("No layout present to add a cell to")));
   }
 
+  lay::CellView cv = view ()->cellview (view ()->active_cellview_index ());
+
   static double s_new_cell_window_size = 2.0;
   static std::string s_new_cell_cell_name;
 

src/plugins/streamers/gds2/unit_tests/dbGDS2ReaderTests.cc

@@ -704,3 +704,24 @@ TEST(5_issue893)
   db::compare_layouts (_this, layout, fn_au, db::WriteGDS2, 1);
 }
 
+//  PCell saved as top cell
+TEST(6_issue1835)
+{
+  db::Manager m (false);
+  db::Layout layout (&m);
+
+  db::LoadLayoutOptions options;
+
+  {
+    tl::InputStream file (tl::testdata () + "/gds/issue_1835.gds");
+    db::Reader reader (file);
+    reader.read (layout, options);
+  }
+
+  tl_assert (layout.begin_top_down () != layout.end_top_cells ());
+  layout.convert_cell_to_static (*layout.begin_top_down ());
+
+  std::string fn_au (tl::testdata () + "/gds/issue_1835_au.gds");
+  db::compare_layouts (_this, layout, fn_au, db::WriteGDS2, 1);
+}
+