From 2a376ceb8dc0aaef39b43eada02b9c94e0d51656 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Thu, 29 Feb 2024 19:45:14 +0100
Subject: [PATCH] add regression test

---
 src/tools/miri/tests/fail/rustc-error2.rs     | 16 ++++++++++++++++
 src/tools/miri/tests/fail/rustc-error2.stderr |  9 +++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 src/tools/miri/tests/fail/rustc-error2.rs
 create mode 100644 src/tools/miri/tests/fail/rustc-error2.stderr

diff --git a/src/tools/miri/tests/fail/rustc-error2.rs b/src/tools/miri/tests/fail/rustc-error2.rs
new file mode 100644
index 00000000000..fd2c5393385
--- /dev/null
+++ b/src/tools/miri/tests/fail/rustc-error2.rs
@@ -0,0 +1,16 @@
+// Regression test for https://github.com/rust-lang/rust/issues/121508.
+struct Struct<T>(T);
+
+impl<T> std::ops::Deref for Struct<T> {
+    type Target = dyn Fn(T);
+    fn deref(&self) -> &assert_mem_uninitialized_valid::Target {
+        //~^ERROR: undeclared crate or module
+        unimplemented!()
+    }
+}
+
+fn main() {
+    let f = Struct(Default::default());
+    f(0);
+    f(0);
+}
diff --git a/src/tools/miri/tests/fail/rustc-error2.stderr b/src/tools/miri/tests/fail/rustc-error2.stderr
new file mode 100644
index 00000000000..de2861a019c
--- /dev/null
+++ b/src/tools/miri/tests/fail/rustc-error2.stderr
@@ -0,0 +1,9 @@
+error[E0433]: failed to resolve: use of undeclared crate or module `assert_mem_uninitialized_valid`
+  --> $DIR/rustc-error2.rs:LL:CC
+   |
+LL |     fn deref(&self) -> &assert_mem_uninitialized_valid::Target {
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `assert_mem_uninitialized_valid`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0433`.