c++ - How do I implement an overloaded copy assignment operator for a reference (proxy) class? -

as assignment have create template bit array class , part of overloading index operator. told use proxy class , given sample code go off of:

class bits { ...     class reference {         bits& b;         int pos;     public:         reference(bits& bs, int p) : b(bs) {             pos = p;         }         reference& operator=(bool bit) {             // set bit in position pos true or false, per bit             if (bit)                 b.data |= (1u << pos);             else                 b.data &= ~(1u << pos);             return *this;         }         operator bool () const {             // return true or false per bit in position pos             return b.data & (1u << pos);         }     };     reference operator[](int pos) {         return reference(*this, pos);     } 

my code reads follows (altered fit bit array):

template <class itype = size_t> class bitarray { ...     class bitproxy {         bitarray& b;         size_t pos;     public:         bitproxy(bitarray& ba, size_t p) : b(ba) {             pos = p;         }         bitproxy& operator=(bool bit) {             b.assign_bit(pos, bit);             return *this;         }         operator bool() const {             return b.read_bit(pos);         }     };      bitproxy operator[](size_t bitpos) {         if (bitpos >= arrsize)             throw logic_error("provided index out of range");         else             return bitproxy(*this, bitpos);     }     bool operator[](size_t pos) const {         if (pos >= arrsize)             throw logic_error("provided index out of range");         else             return read_bit(pos);     } 

my code works , passes of tests (the tbitarray.cpp file) when run in visual studio, doesn't work when run through g++ on mac. instead comes error message:

tbitarray.cpp:141:17: error: object of type 'bitarray<unsigned long>::bitproxy'       cannot assigned because copy assignment operator implicitly       deleted         b9[0] = b10[0] = b10[1];                        ^ ./bitarray.h:166:13: note: copy assignment operator of 'bitproxy' implicitly       deleted because field 'b' of reference type 'bitarray<unsigned long> &'                 bitarray& b;                           ^ 

the reference sample code compiles , runs without issues on both windows or mac.

i understand why copy assignment being implicitly deleted, don't understand why sample code works (when it's in same basic format) , why code run on windows machine, not unix-based machine.

i'm not sure go here , i've tried everything. there sort of workaround this?