[fpc-pascal] Assigning value to ftVariant datatype & varbytes - still stuck

[Reinier Olislagers]

Hi list,

Free Pascal Compiler version 2.5.1 [2011/08/04] for i386

While improving my fcl-db XML export code, I'm testing with ftVariant
types in a bufdataset:
  FieldDef := FTestDataset.FieldDefs.AddFieldDef;
  FieldDef.Name := 'ftVariant';
  FieldDef.DataType := ftVariant;

This works:
  TestString:='The answer to life, the universe, and everything';
  FTestDataset.Append;
  FTestDataSet.FieldByName('ftVarBytes').AsString:=TestString;
  FTestDataSet.FieldByName('ftVarBytes').SetData(TempPChar);
  //FTestDataSet.FieldByName('ftVariant').AsString:=TestString;
  FTestDataset.Post;

However, I can't assign values to ftVariant, whatever combination I try.
The strange thing is that I get an access violation when printing the
fields' contents in a loop, and it happens when getting the value for
ftVarBytes.
Would it have to do with the ASCII NULL delimiter Ludo Brands reported
in http://bugs.freepascal.org/view.php?id=19922

This doesn't work:
  //FTestDataSet.FieldByName('ftVarBytes').AsString:=TestString;
  FTestDataSet.FieldByName('ftVarBytes').SetData(TempPChar);
  FTestDataSet.FieldByName('ftVariant').AsString:=TestString;

nor this:
  //FTestDataSet.FieldByName('ftVarBytes').AsString:=TestString;
  //FTestDataSet.FieldByName('ftVarBytes').SetData(TempPChar);
  FTestDataSet.FieldByName('ftVariant').AsString:=TestString;

nor this:
  FTestDataSet.FieldByName('ftVarBytes').AsString:=TestString;
  FTestDataSet.FieldByName('ftVarBytes').SetData(TempPChar);
  FTestDataSet.FieldByName('ftVariant').AsString:=TestString;

How can I properly assign values to ftVarBytes and ftVariant and
retrieve them?
I know I asked before for ftVarBytes; I just use .AsString:='bla', but
obviously it doesn't work.

Thanks,
Reinier