def run_cargo_rustc(target)
      cargo_args = %w[rustc]
      cargo_args.push(*cargo_manifest_path_args)
      cargo_args << '--release' if target == 'release'
      cargo_args.push(*cargo_rustc_args)
      run_cargo(*cargo_args)
    end
def run_cargo_rustc(target)
      cargo_args = %w[rustc]
      cargo_args.push(*cargo_manifest_path_args)
      cargo_args << '--release' if target == 'release'
      cargo_args.push(*cargo_rustc_args)
      run_cargo(*cargo_args)
    end
Run `cargo rustc`, given a target (i.e., `release` [default] or `debug`).