View difference between Paste ID: dcriF8FA and QWnHiKkv

 #include <boost/phoenix/core.hpp>
 #include <boost/phoenix/function.hpp>
 #include <iostream>
 #include <string>
 #include <vector>
 #include <algorithm>
 
 template<typename T>
 struct Var
 {
     void setMax(int i) {}
     void setMin(int i) {}
     int getMax() { return 0; }
     int getMin() { return 0; }
 };
 
 namespace impl
 {
     template <typename T1>
-    void squeeze(T1 t, int i)
+    void squeeze(T1& t, int i)
     {
         t.first.setMax(t.second.getMax() - i);
         t.second.setMin(t.first.getMin() + i);
     }
 }
 
 BOOST_PHOENIX_ADAPT_FUNCTION(void, squeeze, impl::squeeze, 2)
 
 int main()
 {
     using boost::phoenix::arg_names::_1;
     std::vector<std::pair<Var<int>, Var<double> > > vec;
     std::for_each(vec.begin(), vec.end(), squeeze(_1, 2));
 }