message: remove outdated sysroot management
diff: @@ -421,38 +421,13 @@ fn in_cargo_miri() {
  }
  fn inside_cargo_rustc() {
  - let home = option_env!("RUSTUP_HOME").or(option_env!("MULTIRUST_HOME"));
  - let toolchain = option_env!("RUSTUP_TOOLCHAIN").or(option_env!("MULTIRUST_TOOLCHAIN"));
  - let sys_root = if let Ok(sysroot) = ::std::env::var("MIRI_SYSROOT") {
  - sysroot
  - } else if let (Some(home), Some(toolchain)) = (home, toolchain) {
  - format!("{}/toolchains/{}", home, toolchain)
  - } else {
  - option_env!("RUST_SYSROOT")
  - .map(|s| s.to_owned())
  - .or_else(|| {
  - Command::new("rustc")
  - .arg("--print")
  - .arg("sysroot")
  - .output()
  - .ok()
  - .and_then(|out| String::from_utf8(out.stdout).ok())
  - .map(|s| s.trim().to_owned())
  - })
  - .expect("need to specify `RUST_SYSROOT` env var during miri compilation, or use rustup or multirust")
  - };
  + let sysroot = std::env::var("MIRI_SYSROOT").expect("The wrapper should have set MIRI_SYSROOT");
  - // This conditional check for the `--sysroot` flag is there so that users can call `cargo-miri`
  - // directly without having to pass `--sysroot` or anything.
  - let rustc_args = std::env::args().skip(2);
  - let mut args: Vec<String> = if std::env::args().any(|s| s == "--sysroot") {
  - rustc_args.collect()
  - } else {
  - rustc_args
  + let rustc_args = std::env::args().skip(2); // skip `cargo rustc`
  + let mut args: Vec<String> = rustc_args
  .chain(Some("--sysroot".to_owned()))
  - .chain(Some(sys_root))
  - .collect()
  - };
  + .chain(Some(sysroot))
  + .collect();
  args.splice(0..0, miri::miri_default_args().iter().map(ToString::to_string));
  // See if we can find the `cargo-miri` markers. Those only get added to the binary we want to
  