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: config.rs
    path of file: ./repos/mun/crates/mun_compiler/src/driver
    
    the code of the file until where you have to start completion: use std::path::PathBuf;

pub use mun_codegen::OptimizationLevel;
use mun_target::spec::Target;

/// Describes all the permanent settings that are used during compilations.
#[derive(Debug, Clone)]
pub struct Config {
    /// The target triple to compile the code for.
    pub target: Target,

    /// The opt
    
    fn default() -> Self {
        let target = Target::host_target();
        Config {
            // This unwrap is safe because we only compile for targets that have an implemented host
            // triple.
            target: target.unwrap(),
            optimization_lvl: OptimizationLevel::Default,
            out_dir: None,
            emit_ir: false,
        }
    }