message: no need to do run-time formatting
diff: -#![feature(slice_concat_ext)]
  +#![feature(slice_concat_ext, const_fn)]
  extern crate compiletest_rs as compiletest;
  @@ -13,8 +13,8 @@ macro_rules! eprintln {
  }
  }
  -fn miri_path() -> String {
  - format!("target/{}/miri", env!("PROFILE"))
  +const fn miri_path() -> &'static str {
  + concat!("target/", env!("PROFILE"), "/miri")
  }
  fn compile_fail(sysroot: &Path, path: &str, target: &str, host: &str, fullmir: bool) {
  