Added test

Author: dshynkev

src/test/codegen/issue-53080.rs

@@ -0,0 +1,19 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// A drop([...].clone()) sequence on an Rc should be a no-op
+// In particular, no call to __rust_dealloc should be emitted
+#![crate_type = "lib"]
+use std::rc::Rc;
+
+pub fn foo(t: &Rc<Vec<usize>>) {
+// CHECK-NOT: __rust_dealloc
+    drop(t.clone());
+}