Link error , help me!

Question

ild: (Performing full relink) symbol definitions conflict [...]
ild: (undefined symbol) __type_1 std::remove_copy<std::list<CTestThread*,std::al
locator<CTestThread*> >::iterator,std::list<CTestThread*,std::allocator<CTestThr
ead*> >::iterator,CTestThread*>(__type_0,__type_0,__type_1,const __type_2&) -- r
eferenced in the text segment of ./TestApp.o
ild: (undefined symbol) std::list<CDatabase*,std::allocator<CDatabase*> >::itera
tor std::list<CDatabase*,std::allocator<CDatabase*> >::erase(std::list<CDatabase
*,std::allocator<CDatabase*> >::iterator,std::list<CDatabase*,std::allocator<CDa
tabase*> >::iterator) -- referenced in the text segment of Database/DatabasePool
.o
ild: (undefined symbol) std::list<CTestThread*,std::allocator<CTestThread*> >::i
terator std::list<CTestThread*,std::allocator<CTestThread*> >::erase(std::list<C
TestThread*,std::allocator<CTestThread*> >::iterator,std::list<CTestThread*,std:
:allocator<CTestThread*> >::iterator) -- referenced in the text segment of ./Tes
tApp.o
ild: (undefined symbol) std::list<CManage*,std::allocator<CManage*> >::iterator
std::list<CManage*,std::allocator<CManage*> >::erase(std::list<CManage*,std::all
ocator<CManage*> >::iterator,std::list<CManage*,std::allocator<CManage*> >::iter
ator) -- referenced in the text segment of Manage/ManageSvr.o
why ?

Answer 1

I got this error, too, and here's a short version how I got it:
#include <iostream>
#include <string>
using namespace std;
std::string setting(std::string xx)
   xx.assign("Something assigned");
   return  xx;
int main ()
  std::string yy;
  yy=setting(yy);
  cout << "FINALE: " << yy << endl;
  return 0;
$ make
CC -c -g -DSS_UNIX -I. -g  main.cpp
CC -g -o main main.o   -lnsl -lm -lrt 
ild: (Performing full relink) symbol definitions conflict [...]
++++++TARGET DONE++++++It started when I made the function setting to return std::string. However, the program works as it should.