Doesn't work with `cargo:rustc-env=VAR=VALUE`

[eminfedar]

I need to pass an environment variable which I generate on build.rs in my project.

build.rs:

fn main() {
        println!("cargo:rustc-env=MY_PATH=/path/here");
}

main.rs:

fn main() {
        include_dir!("$MY_PATH"); // doesn't work
        include_dir!(env!("MY_PATH")); // doesn't work either
}

If only I run my cargo build command like this, it works:

MY_PATH=/path/here cargo build

I think it should work with others too. Because users should be able to embed a directory which generated by build.rs dynamically.