Auto merge of #1986 - RalfJung:rustup, r=RalfJung

rustup

Let's see if landing just this works...

Author: bors

rust-version

@@ -1 +1 @@
-3d127e2040b57157936f5f24e114a8b4c9a505ef
+d4de1f230ca30b7ce08fbf453daebf8b2e7ffcc9

src/diagnostics.rs

@@ -254,7 +254,7 @@ fn report_msg<'tcx>(
 ) {
     let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
     let mut err = match diag_level {
-        DiagLevel::Error => tcx.sess.struct_span_err(span, title),
+        DiagLevel::Error => tcx.sess.struct_span_err(span, title).forget_guarantee(),
         DiagLevel::Warning => tcx.sess.struct_span_warn(span, title),
         DiagLevel::Note => tcx.sess.diagnostic().span_note_diag(span, title),
     };