diff -r 9fe6c4633ed6 -r d2cd05c5e01a stage3/print_datatypes_error.cc
--- a/stage3/print_datatypes_error.cc	Fri Mar 09 10:52:23 2012 +0000
+++ b/stage3/print_datatypes_error.cc	Fri Mar 09 17:58:19 2012 +0000
@@ -862,6 +862,15 @@
 }
 
 void *print_datatypes_error_c::visit(NOT_operator_c *symbol) {
+	/* NOTE: the standard allows syntax in which the NOT operator is followed by an optional <il_operand>
+	 *              NOT [<il_operand>]
+	 *       However, it does not define the semantic of the NOT operation when the <il_operand> is specified.
+	 *       We therefore consider it an error if an il_operand is specified!
+	 */
+	if (il_operand != NULL)
+		STAGE3_ERROR(0, symbol, symbol, "'NOT' operator may not have an operand.");
+	if (symbol->candidate_datatypes.size() == 0)
+		STAGE3_ERROR(0, symbol, symbol, "Data type mismatch for 'NOT' operator.");
 	return NULL;
 }