From 911ced003a3600a2a9159921f2a11591485c47da Mon Sep 17 00:00:00 2001
From: Fabian Wolff <fabian.wolff@alumni.ethz.ch>
Date: Fri, 24 Sep 2021 22:42:05 +0200
Subject: [PATCH] Hide `<...> defined here` note if the source is not available

---
 .../src/structured_errors/wrong_number_of_generic_args.rs   | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
index 2e3db4d6d655f..c2038f4e047ce 100644
--- a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
+++ b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
@@ -731,7 +731,11 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
     /// Builds the `type defined here` message.
     fn show_definition(&self, err: &mut DiagnosticBuilder<'_>) {
         let mut spans: MultiSpan = if let Some(def_span) = self.tcx.def_ident_span(self.def_id) {
-            def_span.into()
+            if self.tcx.sess.source_map().span_to_snippet(def_span).is_ok() {
+                def_span.into()
+            } else {
+                return;
+            }
         } else {
             return;
         };