Bug 176107 row.__rownum cannot be directly used as group key
Create a table that bind it to a data set. Insert a group. For the Group On field, click on the "..." button to edit the expression, and select from "Availble Column Bindings" | "Table" | "RowNum". This creates a Group On Expression "row.__rownum". The resulting report design cannot be run. It produces error: Column binding "row.__rownum" does not exist. To workaround this, one must create another binding on the table and set its expression to "row.__rownum", then use the new binding as group key. This should not have been necessary. The "__rownum" binding should be implicitly available in all contexts that have a data set. E.g., it should be usable directly as group key, sort key, and in conditional format expressions, etc. Attached is a sample report that produces the error.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/expression/ExpressionCompilerUtil.java
* @param list
	 * @param expression
	 * @throws DataException
	 */
	private static void populateColumnList( List list,
			IScriptExpression expression, boolean rowMode ) throws DataException
	{
		if ( expression != null )
		{
			List l;
			try
			{
				l = ExpressionUtil.extractColumnExpressions( expression.getText( ),
						rowMode );
			}
			catch ( BirtException e )
			{
				throw DataException.wrap( e );
			}
			for ( int i = 0; i < l.size( ); i++ )
			{
				IColumnBinding cb = (IColumnBinding) l.get( i );
				if ( !list.contains( cb.getResultSetColumnName( ) )
						&& cb.getOuterLevel( ) == 0 )
					list.add( cb.getResultSetColumnName( ) );
			}
		}
	}
}