CONTROLASSIGN

Message        <Context> the assignment expression "<expression>" is
               used as the controlling expression of an if, while or
               for statement.

Description    A common user mistake is to accidentally use
               assignment operator "=" instead of the equality
               operator "==" in an expression that controls a
               transfer.  For example saying if (a = b) instead of
               if (a == b).  While using the assignment operator is
               valid, it is often not what was intended.  When this
               message is enabled, the compiler will detect these
               cases at compile-time.  This can often avoid long
               debugging sessions needed to find the bug in the
               user's program.

User Action    Make sure that the assignment operator is what is
               expected.