Improve error message.

git-svn-id: https://svn.dealii.org/trunk@32238 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/include/deal.II/dofs/dof_accessor.templates.h b/deal.II/include/deal.II/dofs/dof_accessor.templates.h
index 327146e3f59630a48c1d3ce60fa7a78946fd8c7a..2c9af2dcc0cb9dcc6f50e57637b2f2e7af202330 100644 (file)
--- a/deal.II/include/deal.II/dofs/dof_accessor.templates.h
+++ b/deal.II/include/deal.II/dofs/dof_accessor.templates.h
@@ -80,7 +80,12 @@ DoFAccessor<structdim,DH,lda>::DoFAccessor (const DoFAccessor<dim2, DH2, lda2> &
   : BaseClass(other),
     dof_handler(0)
 {
-  Assert (false, ExcInvalidObject());
+  Assert (false, ExcMessage("You are trying to assign iterators that are incompatible. "
+                           "Reasons for incompatibility are that they point to different "
+                           "types of DoFHandlers (e.g., dealii::DoFHandler and "
+                           "dealii::hp::DoFHandler) or that the refer to objects of "
+                           "different dimensionality (e.g., assigning a line iterator "
+                           "to a quad iterator)."));
 }