QUESTCOMPARE1

Message        <Context> the unsigned expression "<expr>" is being
               compared with an equality operator to a constant
               whose value is negative.  This might not be what you
               intended.

Description    An unsigned value and a signed constant whose value
               is negative are being compared for equality.
               Logically, these value would never be equal.  But in
               C the negative constant value is converted to an
               unsigned value before the comparison, and may well
               compare equal.

User Action    Cast (or otherwise rewrite) one of the operands of
               the compare to match the signedness of the other
               operand.