Copy without assign

This class has a user-defined copy constructor but no user-defined assignment operator. If the copy constructor is necessary to manage owned resources then a corresponding assignment operator is usually required. If an object of this type is assigned memory leaks and/or use-after-free errors may occur. Note that a compiler-generated assignment operator will perform only a bit-wise copy for any fields that do not have their own assignment operators defined. Class has user-written copy constructor but no user-written assignment operator
/src/mongo/db/query/optimizer/cascades/memo_defs.h:56: COPY_WITHOUT_ASSIGN 133999 Class "mongo::optimizer::cascades::OrderPreservingABTSet" has a user-written copy constructor "mongo::optimizer::cascades::OrderPreservingABTSet::OrderPreservingABTSet(mongo::optimizer::cascades::OrderPreservingABTSet const &) =delete" but no corresponding user-written assignment operator.
/src/mongo/db/query/optimizer/cascades/memo_defs.h:59: COPY_WITHOUT_ASSIGN 133999 User-written copy constructor.