Index: src/Ice/Patcher.cs
===================================================================
RCS file: /home/cvsroot/icecs/src/Ice/Patcher.cs,v
retrieving revision 1.15
diff -c -r1.15 Patcher.cs
*** src/Ice/Patcher.cs	30 Dec 2005 02:05:35 -0000	1.15
--- src/Ice/Patcher.cs	14 Mar 2006 05:36:52 -0000
***************
*** 72,102 ****
  
  	public override void patch(Ice.Object v)
  	{
              try 
              {
!                 if(_seq is IList)
                  {
!                     if(_index >= _seq.Count)
                      {
                          for(int i = _seq.Count; i <= _index; i++)
                          {
!                             ((IList)_seq).Add(dummyObject); // IList implementation does not permit adding null :-(
                          }
                      }
!                     ((IList)_seq)[_index] = v;
                  }
                  else
                  {
                      ((System.Array)_seq).SetValue(v, _index);
                  }
              }
!             catch(System.Exception)
              {
!                 throw new System.InvalidCastException("expected element of type " + type()
!                                                       + " but received " + v.GetType().FullName); 
              }
  	}
!     
  	private ICollection _seq;
  	private int _index;
      }
--- 72,138 ----
  
  	public override void patch(Ice.Object v)
  	{
+ 	    Debug.Assert(type_ != null);
+ 	    if(v != null && !type_.IsInstanceOfType(v))
+ 	    {
+ 		throw new System.InvalidCastException("expected element of type " + type() +
+ 						      " but received " + v.GetType().FullName); 
+ 	    }
+ 
              try 
              {
!                 if(_seq is CollectionBase)
                  {
!                     if(_index >= _seq.Count) // Need to grow the sequence.
                      {
                          for(int i = _seq.Count; i <= _index; i++)
                          {
!                             ((IList)_seq).Add(dummyObject); // Broken CollectionBase implementation
                          }
                      }
! 
! 		    //
! 		    // Ugly work-around for broken CollectionBase implementation:
! 		    //
! 		    // CollectionBase provides implementations of the IList.Add method
! 		    // and indexer. However, stupidly, these implementations do not permit
! 		    // null to be added or assigned even though, according to the doc, this should work.
! 		    // (Attempts to put a null into the collection raise ArgumentNullException.)
! 		    // That's why the above code grows the sequence by adding a dummy object.
! 		    //
! 		    // Furthermore, CollectionBase.Add and the indexer are (incorrectly) non-virtual so,
! 		    // when we treat _seq as an IList, we always dispatch into the CollectionBase
! 		    // implementation, not into the implementation of the generated sequence type.
! 		    // This makes it impossible to assign v to a sequence element if v is null.
! 		    //
! 		    // The ugly work-around is to use reflection to ensure that we get the
! 		    // actual run-time type of the generated sequence, and then
! 		    // use dynamic invocation to make sure that we dispatch to the generated indexer,
! 		    // instead of the broken indexer provided by CollectionBase.
! 		    //
! 		    if(v == null)
! 		    {
! 			object[] ov = new object[2];
! 			ov[0] = _index;
! 			ov[1] = null;
! 			_seq.GetType().GetProperty("Item").GetSetMethod().Invoke(_seq, ov);
! 		    }
! 		    else
! 		    {
! 			((IList)_seq)[_index] = v;
! 		    }
                  }
                  else
                  {
                      ((System.Array)_seq).SetValue(v, _index);
                  }
              }
!             catch(System.Exception ex)
              {
!                 throw new Ice.MarshalException("Unexpected failure during patching", ex);
              }
  	}
! 
  	private ICollection _seq;
  	private int _index;
      }