1 files changed, 45 insertions, 0 deletions
diff --git a/src/test/ui/derives/clone-debug-dead-code.rs b/src/test/ui/derives/clone-debug-dead-code.rs
new file mode 100644
index 000000000..ab49260c0
--- /dev/null
+++ b/src/test/ui/derives/clone-debug-dead-code.rs
@@ -0,0 +1,45 @@
+// Checks that derived implementations of Clone and Debug do not
+// contribute to dead code analysis (issue #84647).
+
+#![forbid(dead_code)]
+
+struct A { f: () }
+//~^ ERROR: field `f` is never read
+
+#[derive(Clone)]
+struct B { f: () }
+//~^ ERROR: field `f` is never read
+
+#[derive(Debug)]
+struct C { f: () }
+//~^ ERROR: field `f` is never read
+
+#[derive(Debug,Clone)]
+struct D { f: () }
+//~^ ERROR: field `f` is never read
+
+struct E { f: () }
+//~^ ERROR: field `f` is never read
+// Custom impl, still doesn't read f
+impl Clone for E {
+    fn clone(&self) -> Self {
+        Self { f: () }
+    }
+}
+
+struct F { f: () }
+// Custom impl that actually reads f
+impl Clone for F {
+    fn clone(&self) -> Self {
+        Self { f: self.f }
+    }
+}
+
+fn main() {
+    let _ = A { f: () };
+    let _ = B { f: () };
+    let _ = C { f: () };
+    let _ = D { f: () };
+    let _ = E { f: () };
+    let _ = F { f: () };
+}