error C2663: overloads have no legal conversion for 'this' pointer - c++

Question

please help me for this errors
code:
u16 ip_defragment(){
u16 result;
fragip_set::iterator i;
IP_FRAGMENTED new_defrag;
IP* pcurpack = (IP*) malloc(cur.len);
memcpy(pcurpack, cur.data, cur.len);
new_defrag.saddr = cur.saddr;
new_defrag.daddr = cur.daddr;
new_defrag.protocol = cur.ip.ppack->protocol;
new_defrag.id = i2i(cur.ip.ppack->id);
i = ip_frags.find(new_defrag);
if(i != ip_frags.end()){
i->packets.insert(pcurpack);
const_cast<u16&>(i->cur_len) += cur.ip.len - cur.ip.hlen;
const_cast<u32&>(i->last_time) = time();
if(!(cur.ip.bmore_fr) && (i->tot_len == 0)){
const_cast<u16&>(i->tot_len) = cur.ip.fr_offs + cur.ip.len;
}
if(i->cur_len == i->tot_len){
for(set<IP*>::iterator k = i->packets.begin(); k != i->packets.end(); k++){
// must copy to another buffer
if(i2i((*k)->frag_off) & IP_OFFMASK){
memcpy(ip_defrag_buffer, *k, (*k)->ihl<<2);
} else {
memcpy(ip_defrag_buffer + (i2i((*k)->frag_off) & IP_OFFMASK) * 8,
*k + ((*k)->ihl<<2), (i2i((*k)->tot_len))-((*k)->ihl<<2));
}
}
IP* defr_ip = (IP*) &ip_defrag_buffer;
defr_ip->tot_len = i2i(i->tot_len);
defr_ip->frag_off = 0;
result = i->tot_len;
ip_frags.erase(i);
return result;
}
return 0;
}
if(!(cur.ip.bmore_fr)){
new_defrag.tot_len = cur.ip.fr_offs + cur.len;
} else {
new_defrag.tot_len = 0;
}
new_defrag.cur_len = cur.ip.len; // with header size
new_defrag.last_time = time();
i = ip_frags.insert(new_defrag).first;
if(i != ip_frags.end())
i->packets.insert(pcurpack);
return 0;
}
compiled project and view only 2 errors similar
line 15 : i->packets.insert(pcurpack);
end line : i->packets.insert(pcurpack);
error with 2 lines : error C2663: 'std::_Tree<_Traits>::insert' : 4 overloads have no legal conversion for 'this' pointer
IntelliSense: no instance of overloaded function "std::set<_Kty, _Pr, _Alloc>::insert [with _Kty=IP *, _Pr=std::less<IP *>, _Alloc=std::allocator<IP *>]" matches the argument list and object (the object has type qualifiers that prevent a match)
please help me?

Answer 1

I had exact same error with std::set, while passing it to a lambda expression:
C2663 'std::_Tree<std::_Tset_traits<_Kty,_Pr,_Alloc,false>>::insert': 5 overloads have no legal conversion for 'this' pointer
lambda expression prototype was:
[se1, ele1](auto val) {
/* here I was editing se1 set, but above se1 is passed value type */
}
I have changed to:
[&se1, ele1](auto val) {
/* now since se1 set is sent as reference type above, it is good to edit
changes stays as I expect it to be
*/
}
Now compilation succeeds.
I used with count_if function, which calls the lamda expression for eac element, so the compiler knows that modifications should persist in set se1, which is perfectly logical.
If you desire to have the original set unchanged, then send a copy of it.