G++ takes code, Comeau barfs with "error: qualified name is not allowed"

As far as I can tell, this code should be correct. G++ likes it, but
Comeau online hates it.

Errors [redacted] from Comeau online:
ComeauTest.c(47): error: qualified name is not allowed
          std::vector<line_t> v(std::istream_iterator<line_t>
(std::cin),
                                                              ^

ComeauTest.c(49): error: expression must have class type
          std::sort(v.begin(), v.end());
                    ^

ComeauTest.c(49): error: expression must have class type
          std::sort(v.begin(), v.end());
                               ^
[large numbers of STL errors redacted]

-----------------------
#include <iostream>
#include <ostream>
#include <istream>
#include <string>
#include <vector>
#include <algorithm>
#include <iterator>

class line_t
{
  private:
    std::string s;
  public:
    friend std::istream& operator>>(std::istream& is, line_t& l)
    {
      return std::getline(is, l.s);
    }

    friend std::ostream& operator<<(std::ostream& os, const line_t& l)
    {
      return os << l.s;
    }
    const std::string& get_string() const
    {
      return s;
    }
    friend bool operator<(const line_t& l, const line_t& r)
    {
      std::string::size_type pos = l.get_string().find_last_of('/');
      std::string lhs = l.get_string().substr(pos + 1);
      pos = r.get_string().find_last_of('/');
      std::string rhs = r.get_string().substr(pos + 1);
      return lhs < rhs;
    }
};

int main()
{
  std::vector<line_t> v(
    std::istream_iterator<line_t>(std::cin),
    std::istream_iterator<line_t>());
  std::sort(v.begin(), v.end());
  std::copy(v.begin(), v.end(),
    std::ostream_iterator<line_t>(std::cout,"\n"));

}