Internal error on snap (deep mode)

[klayoutmatthias]

The following script throws in internal error with the file from testdata/lvs/vexriscv.oas.gz
("Internal error: ../../../src/db/db/dbDeepRegion.cc:834 v.size () == size_t (1) was not true in Region::snap"):

ly = RBA::CellView::active.layout

dss = RBA::DeepShapeStore::new

ly.layer_indexes.each do |li|

  puts ly.get_info(li)

  r = RBA::Region::new(ly.top_cell.begin_shapes_rec(li), dss)
  
  r.merged_semantics = false
  r.snap(19, 19)

  # challenge: modifies the backannotation cellmap:
  ly.clear_layer(li)
  r.insert_into(ly, ly.top_cell.cell_index, li)
  
end

The reason is obviously a variant cell consistency issue after writing back the layers into the original layout.

The following script version works (producing a new layout):

# WORKS!
ly = RBA::CellView::active.layout

dss = RBA::DeepShapeStore::new

RBA::MainWindow::instance.create_layout(1)
lyout = RBA::CellView::active.layout
lyout.create_cell("TOP")

ly.layer_indexes.each do |li|

  puts ly.get_info(li)

  r = RBA::Region::new(ly.top_cell.begin_shapes_rec(li), dss)
  
  r.merged_semantics = false
  r.snap(19, 19)

  liout = lyout.layer(ly.get_info(li))
  r.insert_into(lyout, lyout.top_cell.cell_index, liout)
 
end

RBA::LayoutView::current.add_missing_layers

while this creates an ultimate challenge because it combines clip and snap variants:

ly = RBA::CellView::active.layout

dss = RBA::DeepShapeStore::new

region = RBA::DBox::new(121, 177, 819, 915)

ly.layer_indexes.each do |li|

  puts ly.get_info(li)

  r = RBA::Region::new(ly.top_cell.begin_shapes_rec_touching(li, region), dss)
  
  r.merged_semantics = false
  r.snap(19, 19)

  # challenge: modifies the backannotation cellmap with clip variants!
  ly.clear_layer(li)
  r.insert_into(ly, ly.top_cell.cell_index, li)
  
end