PHP extension with Windows EMIT error

Question

I am developing a PHP extension with Visual Studio 2015. I followed a tutorial and everything worked perfectly, the problem started when I tried to use the variable Std::string. When I do the string include I get the following build error:

variable "EMIT" is not a type name

my file stdafx. h:

    #ifdef PHP_WIN32
    #pragma once
    #include "zend_config.w32.h"
    #include "php.h"
    #endif

    #include <string> //esta linha que gera o erro.