message: actually, we can use a plain constant
diff: -#![feature(slice_concat_ext, const_fn)]
  +#![feature(slice_concat_ext)]
  extern crate compiletest_rs as compiletest;
  @@ -13,15 +13,13 @@ macro_rules! eprintln {
  }
  }
  -const fn miri_path() -> &'static str {
  - concat!("target/", env!("PROFILE"), "/miri")
  -}
  +const MIRI_PATH: &'static str = concat!("target/", env!("PROFILE"), "/miri");
  fn compile_fail(sysroot: &Path, path: &str, target: &str, host: &str, fullmir: bool) {
  eprintln!("## Running compile-fail tests in {} against miri for target {}", path, target);
  let mut config = compiletest::default_config();
  config.mode = "compile-fail".parse().expect("Invalid mode");
  - config.rustc_path = miri_path().into();
  + config.rustc_path = MIRI_PATH.into();
  if fullmir {
  if host != target {
  // skip fullmir on nonhost
  @@ -60,7 +58,7 @@ fn miri_pass(path: &str, target: &str, host: &str, fullmir: bool, opt: bool) {
  config.src_base = PathBuf::from(path);
  config.target = target.to_owned();
  config.host = host.to_owned();
  - config.rustc_path = miri_path().into();
  + config.rustc_path = MIRI_PATH.into();
  let mut flags = Vec::new();
  if fullmir {
  if host != target {
  