Fix backend search path

[jklincn]

std::filesystem::current_path() returns path without '/', leading to path error when trying to load the base backend.

I provide a simple example to demonstrate.

lin@amx:~/bs$ touch test.txt
lin@amx:~/bs$ cat error.cpp
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
 
int main()
{
    fs::path search_path = fs::current_path();
    fs::path filename = "test.txt";
    fs::path path = search_path.native() + filename.native();
    if (fs::exists(path)) {
        std::cout << "File exists." << std::endl;
    } else {
        std::cout << "File does not exist." << std::endl;
    }
}
lin@amx:~/bs$ g++ error.cpp --std=c++17
lin@amx:~/bs$ ./a.out 
File does not exist.
lin@amx:~/bs$ diff error.cpp correct.cpp 
7c7
<     fs::path search_path = fs::current_path();
---
>     fs::path search_path = fs::current_path() / "";
lin@amx:~/bs$ g++ correct.cpp --std=c++17
lin@amx:~/bs$ ./a.out 
File exists.

Refenence: https://en.cppreference.com/w/cpp/filesystem/current_path

[slaren]

We should probably use the / operator to build the path instead:

fs::path path = search_path / filename;

[jklincn]

Thank you! I have made the changes and also addressed a few other places where .native() was used.