UNDEFVARFETCH

Message        <Context> the expression "<expr>" modifies "<var>",
               and fetches its value in a computation that is not
               used to produce the modified value without an
               intervening sequence point.  This behavior is
               undefined.

Description    The compiler has detected a case where the same
               variable has been modified and fetched in a
               computation that does not later modify that same
               variable.  Because the order of the variable fetch
               and store is not defined, this expression might
               produce different results on different platforms.

User Action    Rewrite the expression so that if a variable is
               stored to, it is fetched only to determine the value
               to be stored.