message: clamp down on hacks in compiletest
diff: @@ -3,9 +3,9 @@ extern crate compiletest_rs as compiletest;
  use std::path::{PathBuf, Path};
  use std::io::Write;
  -fn compile_fail(sysroot: &str) {
  - let flags = format!("--sysroot {} -Dwarnings", sysroot);
  - for_all_targets(sysroot, |target| {
  +fn compile_fail(sysroot: &Path) {
  + let flags = format!("--sysroot {} -Dwarnings", sysroot.to_str().expect("non utf8 path"));
  + for_all_targets(&sysroot, |target| {
  let mut config = compiletest::default_config();
  config.host_rustcflags = Some(flags.clone());
  config.mode = "compile-fail".parse().expect("Invalid mode");
  @@ -49,8 +49,10 @@ fn is_target_dir<P: Into<PathBuf>>(path: P) -> bool {
  path.metadata().map(|m| m.is_dir()).unwrap_or(false)
  }
  -fn for_all_targets<F: FnMut(String)>(sysroot: &str, mut f: F) {
  - for entry in std::fs::read_dir(format!("{}/lib/rustlib/", sysroot)).unwrap() {
  +fn for_all_targets<F: FnMut(String)>(sysroot: &Path, mut f: F) {
  + let target_dir = sysroot.join("lib").join("rustlib");
  + println!("target dir: {}", target_dir.to_str().unwrap());
  + for entry in std::fs::read_dir(target_dir).expect("invalid sysroot") {
  let entry = entry.unwrap();
  if !is_target_dir(entry.path()) { continue; }
  let target = entry.file_name().into_string().unwrap();
  @@ -62,24 +64,23 @@ fn for_all_targets<F: FnMut(String)>(sysroot: &str, mut f: F) {
  #[test]
  fn compile_test() {
  - // Taken from https://github.com/Manishearth/rust-clippy/pull/911.
  - let home = option_env!("RUSTUP_HOME").or(option_env!("MULTIRUST_HOME"));
  - let toolchain = option_env!("RUSTUP_TOOLCHAIN").or(option_env!("MULTIRUST_TOOLCHAIN"));
  - let sysroot = match (home, toolchain) {
  - (Some(home), Some(toolchain)) => format!("{}/toolchains/{}", home, toolchain),
  - _ => option_env!("RUST_SYSROOT")
  - .expect("need to specify RUST_SYSROOT env var or use rustup or multirust")
  - .to_owned(),
  - };
  + let sysroot = std::process::Command::new("rustc")
  + .arg("--print")
  + .arg("sysroot")
  + .output()
  + .expect("rustc not found")
  + .stdout;
  + let sysroot = std::str::from_utf8(&sysroot).expect("sysroot is not utf8").trim();
  + let sysroot = &Path::new(&sysroot);
  + let host = std::process::Command::new("rustc")
  + .arg("-vV")
  + .output()
  + .expect("rustc not found for -vV")
  + .stdout;
  + let host = std::str::from_utf8(&host).expect("sysroot is not utf8");
  + let host = host.split("\nhost: ").skip(1).next().expect("no host: part in rustc -vV");
  + let host = host.split("\n").next().expect("no \n after host");
  run_pass();
  - let host = Path::new(&sysroot).file_name()
  - .expect("sysroot has no last par")
  - .to_str()
  - .expect("sysroot contains non utf8")
  - .splitn(2, '-')
  - .skip(1)
  - .next()
  - .expect("target dir not prefixed");
  for_all_targets(&sysroot, |target| {
  miri_pass("tests/run-pass", &target, host);
  if let Ok(path) = std::env::var("MIRI_RUSTC_TEST") {
  