message: better way to get an absolute path
diff: @@ -259,19 +259,8 @@ fn setup(subcommand: MiriCommand) {
  let rust_src = match std::env::var_os("XARGO_RUST_SRC") {
  Some(val) => {
  let path = PathBuf::from(val);
  - let path = path.canonicalize().unwrap_or(path);
  -
  - // On Windows, this produces a path starting with `\\?\`, which xargo cannot deal with.
  - // Strip that prefix; the resulting path should still be valid.
  - #[cfg(windows)]
  - let path = {
  - let str = path.into_os_string().into_string()
  - .expect("non-unicode paths are currently not supported");
  - let str = str.strip_prefix(r"\\?\").map(String::from).unwrap_or(str);
  - PathBuf::from(str)
  - };
  -
  - path
  + // Make path absolute, but not via `canonicalize` (which does not work very well on Windows).
  + env::current_dir().unwrap().join(path)
  }
  None => {
  // Check for `rust-src` rustup component.
  