You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: build.rs
    path of file: ./repos/emacs-ng/rust_src/crates/lsp_json
    
    the code of the file until where you have to start completion: extern crate ng_bindgen;

use ng_bindgen::{generate_crate_exports, BuildError};

fn main() {
    // TODO watch relevent files to re rerun, rs files under src?

    let path = std::path::PathBuf::from(
    
fn main() {
    // TODO watch relevent files to re rerun, rs files under src?

    let path = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    if let Err(e) = generate_crate_exports(&path) {
        match e {
            BuildError::IOError(msg) => {
                eprintln!("{}", msg);
                std::process::exit(3);
            }
            BuildError::Lint(msg) => {
                msg.fail(1);
            }
        }
    }
}