From 37aad77ce25229454d796bc85894ae0826ac937a Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Fri, 17 Jul 2015 08:26:14 -0400
Subject: [PATCH] Add regression test for #25954 (cyclic closure type), which
 is now impossible.

---
 .../closure-referencing-itself-issue-25954.rs | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 src/test/compile-fail/closure-referencing-itself-issue-25954.rs

diff --git a/src/test/compile-fail/closure-referencing-itself-issue-25954.rs b/src/test/compile-fail/closure-referencing-itself-issue-25954.rs
new file mode 100644
index 000000000000..9357d0e76157
--- /dev/null
+++ b/src/test/compile-fail/closure-referencing-itself-issue-25954.rs
@@ -0,0 +1,28 @@
+// Copyright 2012 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.
+
+// Regression test for #25954: detect and reject a closure type that
+// references itself.
+
+use std::cell::{Cell, RefCell};
+
+struct A<T: Fn()> {
+    x: RefCell<Option<T>>,
+    b: Cell<i32>,
+}
+
+fn main() {
+    let mut p = A{x: RefCell::new(None), b: Cell::new(4i32)};
+
+    // This is an error about types of infinite size:
+    let q = || p.b.set(5i32); //~ ERROR mismatched types
+
+    *(p.x.borrow_mut()) = Some(q);
+}