From b929f721198c9c9467c0a427a23a974be0baa0d4 Mon Sep 17 00:00:00 2001
From: Dan Aloni <alonid@gmail.com>
Date: Sat, 11 Jul 2020 11:03:54 +0300
Subject: [PATCH 1/2] Fix try_print_visible_def_path_recur for opt_def_id usage

This to fix #74081.
---
 src/librustc_middle/ty/print/pretty.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc_middle/ty/print/pretty.rs b/src/librustc_middle/ty/print/pretty.rs
index 9dda208b5a0da..3809c8d245bbe 100644
--- a/src/librustc_middle/ty/print/pretty.rs
+++ b/src/librustc_middle/ty/print/pretty.rs
@@ -393,7 +393,7 @@ pub trait PrettyPrinter<'tcx>:
                     .tcx()
                     .item_children(visible_parent)
                     .iter()
-                    .find(|child| child.res.def_id() == def_id)
+                    .find(|child| child.res.opt_def_id() == Some(def_id))
                     .map(|child| child.ident.name);
                 if let Some(reexport) = reexport {
                     *name = reexport;

From f5de23b5c132db8064c98e0e20ef216d6defdc44 Mon Sep 17 00:00:00 2001
From: Dan Aloni <alonid@gmail.com>
Date: Sat, 11 Jul 2020 14:42:08 +0300
Subject: [PATCH 2/2] Add the test case mentioned in #74236

---
 src/test/ui/issues/issue-74236/auxiliary/dep.rs |  8 ++++++++
 src/test/ui/issues/issue-74236/main.rs          |  9 +++++++++
 src/test/ui/issues/issue-74236/main.stderr      | 11 +++++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 src/test/ui/issues/issue-74236/auxiliary/dep.rs
 create mode 100644 src/test/ui/issues/issue-74236/main.rs
 create mode 100644 src/test/ui/issues/issue-74236/main.stderr

diff --git a/src/test/ui/issues/issue-74236/auxiliary/dep.rs b/src/test/ui/issues/issue-74236/auxiliary/dep.rs
new file mode 100644
index 0000000000000..45f2601d307c8
--- /dev/null
+++ b/src/test/ui/issues/issue-74236/auxiliary/dep.rs
@@ -0,0 +1,8 @@
+// edition:2018
+
+mod private { pub struct Pub; }
+
+// Reexport built-in attribute without a DefId (requires Rust 2018).
+pub use cfg_attr as attr;
+// This export needs to be after the built-in attribute to trigger the bug.
+pub use private::Pub as Renamed;
diff --git a/src/test/ui/issues/issue-74236/main.rs b/src/test/ui/issues/issue-74236/main.rs
new file mode 100644
index 0000000000000..daa7cfcf9a106
--- /dev/null
+++ b/src/test/ui/issues/issue-74236/main.rs
@@ -0,0 +1,9 @@
+// edition:2018
+// aux-build:dep.rs
+// compile-flags:--extern dep
+
+fn main() {
+    // Trigger an error that will print the path of dep::private::Pub (as "dep::Renamed").
+    let () = dep::Renamed;
+    //~^ ERROR mismatched types
+}
diff --git a/src/test/ui/issues/issue-74236/main.stderr b/src/test/ui/issues/issue-74236/main.stderr
new file mode 100644
index 0000000000000..51d4833e01432
--- /dev/null
+++ b/src/test/ui/issues/issue-74236/main.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+  --> $DIR/main.rs:7:9
+   |
+LL |     let () = dep::Renamed;
+   |         ^^   ------------ this expression has type `dep::Renamed`
+   |         |
+   |         expected struct `dep::Renamed`, found `()`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.