Simple use of strings, returning strings from functions in C++

OK.

It's been a while since I wrote any C++.

And I'm rusty.

So what am I doing wrong here, and why?

#include <iostream>

std::string hello() {
  return "another green world";
}

int main(int argc, char **argv) {
  std::cout << hello() << std::endl;    
  return 0;
}

Then compiling with :

gcc test.cpp -o test

gives me

/tmp/ccxCCo47.o: In function `hello[abi:cxx11]()':
test.cpp:(.text+0x34): undefined reference to `std::allocator<char>::allocator()'
test.cpp:(.text+0x4b): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&)'
test.cpp:(.text+0x57): undefined reference to `std::allocator<char>::~allocator()'
test.cpp:(.text+0x7b): undefined reference to `std::allocator<char>::~allocator()'
/tmp/ccxCCo47.o: In function `main':
test.cpp:(.text+0xcb): undefined reference to `std::cout'
test.cpp:(.text+0xd0): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <char, std::char_traits<char>, std::allocator<char> >(std::basic_ostream<char, std::char_traits<char> >&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
test.cpp:(.text+0xda): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
test.cpp:(.text+0xe5): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
test.cpp:(.text+0xf1): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
test.cpp:(.text+0x116): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
/tmp/ccxCCo47.o: In function `__static_initialization_and_destruction_0(int, int)':
test.cpp:(.text+0x156): undefined reference to `std::ios_base::Init::Init()'
test.cpp:(.text+0x16b): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccxCCo47.o:(.data.rel.local.DW.ref.__gxx_personality_v0[DW.ref.__gxx_personality_v0]+0x0): undefined reference to `__gxx_personality_v0'
collect2: error: ld returned 1 exit status