c – 与字符串(GCC)一起使用时对函数模板的未定义引用

replace_all.cc

template < class T >
T replace_all(
        T const &search,T const &replace,T const &subject
) {
        T result;

        typename T::size_type done = 0;
        typename T::size_type pos;
        while ((pos = subject.find(search,done)) != T::npos) {
                result.append (subject,done,pos - done);
                result.append (replace);
                done = pos + search.size ();
        }
        result.append(subject,subject.max_size());
        return result;
}

test.cc

#include <iostream>

template < class T >
T replace_all(
        T const &search,T const &subject
);

// #include "replace_all.cc"

using namespace std;

int main()
{
        string const a = "foo bar fee boor foo barfoo b";
        cout << replace_all<string>("foo","damn",a) << endl;
        return 0;
}

当我尝试使用gcc 4.1.2编译它时

g++ -W -Wall -c replace_all.cc  
g++ -W -Wall -c test.cc  
g++ test.o replace_all.o

我明白了：

test.o: In function `main':
test.cc:(.text+0x13b): undefined reference to `
   std::basic_string<char,std::char_traits<char>,std::allocator<char> >
   replace_all< std::basic_string<char,std::allocator<char> > >(
       std::basic_string<char,std::allocator<char> > const&,std::basic_string<char,std::allocator<char> > const&
   )
'
collect2: ld returned 1 exit status

但是当我在test.cc中取消注释#include“replace_all.cc”并以这种方式编译时：

g++ -W -Wall test.cc

该程序链接并产生预期的输出：

damn bar fee boor damn bardamn b

为什么链接失败,我该怎么做才能使它工作？