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 1/2] 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 3717ee7143c..c726885337e 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));
             }
         }
     }

From 652f2c753aed97261f5d988f0a2b50aa6508964c Mon Sep 17 00:00:00 2001
From: ishitatsuyuki <ishitatsuyuki@gmail.com>
Date: Mon, 4 Feb 2019 19:26:46 +0900
Subject: [PATCH 2/2] Add test

---
 src/test/ui/stability-in-private-module.rs     | 4 ++++
 src/test/ui/stability-in-private-module.stderr | 9 +++++++++
 2 files changed, 13 insertions(+)
 create mode 100644 src/test/ui/stability-in-private-module.rs
 create mode 100644 src/test/ui/stability-in-private-module.stderr

diff --git a/src/test/ui/stability-in-private-module.rs b/src/test/ui/stability-in-private-module.rs
new file mode 100644
index 00000000000..f12e9198b0d
--- /dev/null
+++ b/src/test/ui/stability-in-private-module.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let _ = std::thread::thread_info::current_thread();
+    //~^ERROR module `thread_info` is private
+}
diff --git a/src/test/ui/stability-in-private-module.stderr b/src/test/ui/stability-in-private-module.stderr
new file mode 100644
index 00000000000..c3edd62a15e
--- /dev/null
+++ b/src/test/ui/stability-in-private-module.stderr
@@ -0,0 +1,9 @@
+error[E0603]: module `thread_info` is private
+  --> $DIR/stability-in-private-module.rs:2:26
+   |
+LL |     let _ = std::thread::thread_info::current_thread();
+   |                          ^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0603`.