From 526a398c77e7be8b437ea4b7cae06e0f3a026155 Mon Sep 17 00:00:00 2001
From: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
Date: Mon, 4 Feb 2019 18:04:33 +0900
Subject: [PATCH] Fix #58101

---
 src/librustc/middle/stability.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/librustc/middle/stability.rs b/src/librustc/middle/stability.rs
index 3717ee7143c55..c726885337ea8 100644
--- a/src/librustc/middle/stability.rs
+++ b/src/librustc/middle/stability.rs
@@ -765,7 +765,9 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 }
             }
             EvalResult::Unmarked => {
-                span_bug!(span, "encountered unmarked API: {:?}", def_id);
+                // The API could be uncallable for other reasons, for example when a private module
+                // was referenced.
+                self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
             }
         }
     }