Untitled

#include<iostream>
#include<string>
#include<vector>

int main()
{
    std::vector<int> v1;
    int i;
    while(std::cin>>i)
    {
        v1.push_back(i);
    }

    for(i : v1) //for (int i:v1) works
        std::cout<<i<<"t";
    cout<<std::endl;
    return 0;
}

for (auto it = range.begin(), end = range.end(); it != end; ++it) {
   use(*it);
}

for (<range-decl>: <range>) { <body> }

{
    auto&& range = <range>;        // keep the range alive!
    auto   it    = begin(range);   // actually, reality is bit more complicated
    auto   end   = end(range);     // actually, reality is a bit more complicated
    for (; begin != end; ++it) {
        <range-decl> = *it;        // this is the rewrite causing your issue
        <body>
    }
}

for ( declaration : range ) statement;