From dd19bf0843113904e9763d55207e3be9120756df Mon Sep 17 00:00:00 2001
From: Jeffrey Seyfried <jeffrey.seyfried@gmail.com>
Date: Fri, 7 Oct 2016 07:35:43 +0000
Subject: [PATCH 1/2] Support importing inaccessible `extern crate`s with a
 warning again.

---
 src/librustc_resolve/resolve_imports.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/librustc_resolve/resolve_imports.rs b/src/librustc_resolve/resolve_imports.rs
index 4689c4ded5c0a..e33668b6fe940 100644
--- a/src/librustc_resolve/resolve_imports.rs
+++ b/src/librustc_resolve/resolve_imports.rs
@@ -197,7 +197,8 @@ impl<'a> Resolver<'a> {
         // If the resolution doesn't depend on glob definability, check privacy and return.
         if let Some(result) = self.try_result(&resolution, ns) {
             return result.and_then(|binding| {
-                if self.is_accessible(binding.vis) && !is_disallowed_private_import(binding) {
+                if self.is_accessible(binding.vis) && !is_disallowed_private_import(binding) ||
+                   binding.is_extern_crate() { // c.f. issue #37020
                     Success(binding)
                 } else {
                     Failed(None)

From 4080efd274f99ed0f6ee610086c5dce5a6168954 Mon Sep 17 00:00:00 2001
From: Jeffrey Seyfried <jeffrey.seyfried@gmail.com>
Date: Fri, 7 Oct 2016 09:23:41 +0000
Subject: [PATCH 2/2] Add regression test.

---
 src/test/run-pass/issue-37020.rs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 src/test/run-pass/issue-37020.rs

diff --git a/src/test/run-pass/issue-37020.rs b/src/test/run-pass/issue-37020.rs
new file mode 100644
index 0000000000000..7d0d20269aba7
--- /dev/null
+++ b/src/test/run-pass/issue-37020.rs
@@ -0,0 +1,25 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(private_in_public)]
+
+mod foo {
+    pub mod bar {
+        extern crate core;
+    }
+}
+
+mod baz {
+    pub use foo::bar::core;
+}
+
+fn main() {
+    baz::core::cell::Cell::new(0u32);
+}