why run program with boost::process::spawn with modifed PATH environment failed?

Question

the code as follow:

#include <boost/process.hpp>

#include <iostream>

int main()
{
    // cmd
    // std::string cmd{"g++.exe"}; // ok
    std::string cmd{"wx.exe"}; // not work
    std::string cmd_path{"E:\\app\\lang\\C\\exe\\examples\\libraries\\wx\\build_CodeBlocks"};

    // env
    boost::process::environment env{boost::this_process::environment()};

    env["PATH"] += cmd_path;

    std::cout << env["PATH"].to_string() << std::endl;

    // run
    // boost::process::spawn(cmd, env);
    // boost::process::spawn(cmd_path + "/" + cmd, env);

    boost::filesystem::path p = boost::process::search_path(cmd);
    if (boost::filesystem::exists(p))
    {
        std::cout << p << std::endl;
    }
    else
    {
        std::cout << cmd << " does not exists!" << std::endl;
        return -1;
    }

    boost::process::spawn(p, env);

    return 0;
}

i think my code is same as the example in here(the bottom of that page), but it doesn't work.

the modifed PATH as follow:

C:\Users\Administrator\bin;E:\app\git\PortableGit\mingw32\bin;E:\app\git\PortableGit\usr\local\bin;E:\app\git\PortableGit\usr\bin;E:\app\git\PortableGit\usr\bin;E:\app\git\PortableGit\mingw32\bin;E:\app\git\PortableGit\usr\bin;C:\Users\Administrator\bin;C:\windows\system32;C:\windows;C:\windows\System32\Wbem;C:\windows\System32\WindowsPowerShell\v1.0;E:\app\git\PortableGit\usr\bin\vendor_perl;E:\app\git\PortableGit\usr\bin\core_perl;E:/app/lang/C/exe/examples/libraries/wx/build_CodeBlocks

the cmd_path is appended at the end.

the error message as follow:

This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. terminate called after throwing an instance of 'boost::process::process_error' what(): CreateProcess failed: No such device or address

why?

when cmd is g++, which is in the old unmodified PATH, it works.

can anyone help?

conclusion: the spawned process did not search the updated PATH environment.