Do not panic on tuple struct access out of bounds

src/librustc_save_analysis/dump_visitor.rs

@@ -1665,13 +1665,16 @@ fn visit_expr(&mut self, ex: &'l ast::Expr) {
                         if !self.span.filter_generated(sub_span, ex.span) {
                             let span =
                                 self.span_from_span(sub_span.expect("No span found for var ref"));
-                            let ref_id =
-                                ::id_from_def_id(def.non_enum_variant().fields[idx.node].did);
-                            self.dumper.dump_ref(Ref {
-                                kind: RefKind::Variable,
-                                span,
-                                ref_id,
-                            });
+                            if let Some(field) = def.non_enum_variant().fields.get(idx.node) {
+                                let ref_id = ::id_from_def_id(field.did);
+                                self.dumper.dump_ref(Ref {
+                                    kind: RefKind::Variable,
+                                    span,
+                                    ref_id,
+                                });
+                            } else {
+                                return;
+                            }
                         }
                     }
                     ty::TyTuple(..) => {}

src/test/run-make/save-analysis-fail/foo.rs

@@ -462,4 +462,7 @@ fn new(f: u32) -> Rls699 {
 
 fn invalid_tuple_struct_access() {
     bar.0;
+
+    struct S;
+    S.0;
 }