1 files changed, 52 insertions, 0 deletions
diff --git a/src/test/ui/autoref-autoderef/issue-38940.rs b/src/test/ui/autoref-autoderef/issue-38940.rs
new file mode 100644
index 000000000..d2f1c6e32
--- /dev/null
+++ b/src/test/ui/autoref-autoderef/issue-38940.rs
@@ -0,0 +1,52 @@
+// issue-38940: error printed twice for deref recursion limit exceeded
+// Test that the recursion limit can be changed. In this case, we have
+// deeply nested types that will fail the `Send` check by overflow
+// when the recursion limit is set very low.
+// compile-flags: -Zdeduplicate-diagnostics=yes
+
+#![allow(dead_code)]
+#![recursion_limit = "10"]
+macro_rules! link {
+    ($outer:ident, $inner:ident) => {
+        struct $outer($inner);
+        impl $outer {
+            fn new() -> $outer {
+                $outer($inner::new())
+            }
+        }
+        impl std::ops::Deref for $outer {
+            type Target = $inner;
+            fn deref(&self) -> &$inner {
+                &self.0
+            }
+        }
+    };
+}
+
+struct Bottom;
+
+impl Bottom {
+    fn new() -> Bottom {
+        Bottom
+    }
+}
+
+link!(Top, A);
+link!(A, B);
+link!(B, C);
+link!(C, D);
+link!(D, E);
+link!(E, F);
+link!(F, G);
+link!(G, H);
+link!(H, I);
+link!(I, J);
+link!(J, K);
+link!(K, Bottom);
+
+fn main() {
+    let t = Top::new();
+    let x: &Bottom = &t;
+    //~^ ERROR mismatched types
+    //~| ERROR reached the recursion limit while auto-dereferencing `J`
+}