[Boost-users] [range] strange behaviour with range-based for loop and adaptors

Subject: [Boost-users] [range] strange behaviour with range-based for loop and adaptors
From: Nathan Ridge (zeratul976_at_[hidden])
Date: 2011-03-12 05:12:33

Hello,
 
I am experiencing some strange behaviour when using adaptors with a range-based for loop.
 
Here's what I'm trying:
 
#include <vector>
#include <iostream>
#include <boost/foreach.hpp>
#include <boost/range/adaptor/transformed.hpp>
 
std::vector<int> f()
{
    return std::vector<int>{1, 2, 3, 4};
}
 
int add1(int x) { return x + 1; }
 
int main()
{
    for (int i : f() | boost::adaptors::transformed(add1))
        std::cout << i << ' ';
    std::cout << '\n';
}

 
The output is 1 3 4 5, instead of the 2 3 4 5 that I would expect.
 
Is there something funny going on with temporaries?
Does the temporary returned by f() not stick around for the duration of the loop?
 
Thanks,
Nate.