1 files changed, 32 insertions, 0 deletions
diff --git a/src/test/ui/lint/issue-20343.rs b/src/test/ui/lint/issue-20343.rs
new file mode 100644
index 000000000..000b63984
--- /dev/null
+++ b/src/test/ui/lint/issue-20343.rs
@@ -0,0 +1,32 @@
+// run-pass
+#![allow(unused_variables)]
+// Regression test for Issue #20343.
+
+// pretty-expanded FIXME #23616
+
+#![deny(dead_code)]
+
+struct B { b: u32 }
+struct C;
+struct D;
+
+trait T<A> { fn dummy(&self, a: A) { } }
+impl<A> T<A> for () {}
+
+impl B {
+    // test for unused code in arguments
+    fn foo(B { b }: B) -> u32 { b }
+
+    // test for unused code in return type
+    fn bar() -> C { unsafe { ::std::mem::transmute(()) } }
+
+    // test for unused code in generics
+    fn baz<A: T<D>>() {}
+}
+
+pub fn main() {
+    let b = B { b: 3 };
+    B::foo(b);
+    B::bar();
+    B::baz::<()>();
+}