Merge remote-tracking branch 'origin/master' into rustup

diff --cc tests/compiletest.rs
index 8070f817bcf6a72159a453b7a107b055d6b24ed4,0e6fa3d2a1fc7e40baf4c7337c697f01d12a6844..0b2058597e185ab21ca826b36495bf6c46edbd74
--- 1/tests/compiletest.rs
--- 2/tests/compiletest.rs
+++ b/tests/compiletest.rs
@@@ -98,21 -88,6 +98,17 @@@ fn miri_pass(sysroot: &Path, path: &str
          target,
          opt_str
      ).green().bold());
-         // FIXME: Using level 1 (instead of 3) for now, as the optimizer is pretty broken
-         // and crashes...
-         // Level 0 and 1 are not the same, so this still gives us *some* coverage.
-         // See https://github.com/rust-lang/rust/issues/50411
-         flags.push("-Zmir-opt-level=1".to_owned());
 +
 +    let mut flags = Vec::new();
 +    flags.push(format!("--sysroot {}", sysroot.display()));
 +    flags.push("-Dwarnings -Dunused".to_owned()); // overwrite the -Aunused in compiletest-rs
 +    flags.push("-Zmir-emit-validate=1".to_owned());
 +    if opt {
++        flags.push("-Zmir-opt-level=3".to_owned());
 +    } else {
 +        flags.push("-Zmir-opt-level=0".to_owned());
 +    }
 +
      let mut config = compiletest::Config::default().tempdir();
      config.mode = "ui".parse().expect("Invalid mode");
      config.src_base = PathBuf::from(path);