Undefined reference to std::cout?

I started with the easiest piece of code

#include <iostream>
using namespace std;

int main() {
  cout << "Hello World!";
  return 0;
}

I setup VScode to run C++ and this is tasks.json

{
    "tasks": [
        {
            "type": "cppbuild",
            "label": "C/C++: gcc build active file",
            "command": "/usr/bin/gcc",
            "args": [
                "-fdiagnostics-color=always",
                "-g",
                "${file}",
                "-o",
                "${fileDirname}/${fileBasenameNoExtension}"
            ],
            "options": {
                "cwd": "${fileDirname}"
            },
            "problemMatcher": [
                "$gcc"
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            },
            "detail": "Task generated by Debugger."
        }
    ],
    "version": "2.0.0"
}

when I run the script I get

Starting build...
/usr/bin/gcc -fdiagnostics-color=always -g /Projects/c++/primo.cpp -o /Projects/c++/primo
/usr/bin/ld: /tmp/ccoasAow.o: warning: relocation against `_ZSt4cout' in read-only section `.text'
/usr/bin/ld: /tmp/ccoasAow.o: in function `main':
/Projects/c++/primo.cpp:5: undefined reference to `std::cout'
/usr/bin/ld: /Projects/c++/primo.cpp:5: undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/usr/bin/ld: /tmp/ccoasAow.o: in function `__static_initialization_and_destruction_0(int, int)':
/usr/include/c++/11/iostream:74: undefined reference to `std::ios_base::Init::Init()'
/usr/bin/ld: /usr/include/c++/11/iostream:74: undefined reference to `std::ios_base::Init::~Init()'
/usr/bin/ld: warning: creating DT_TEXTREL in a PIE
collect2: error: ld returned 1 exit status

Build finished with error(s).

 *  The terminal process terminated with exit code: -1. 
 *  Terminal will be reused by tasks, press any key to close it.

I see there is an undefined reference to 'std::cout' but don't know how to solve it.

If I run the code in terminal, it works

Use g++ to compile C++, as gcc is for C.