Auto merge of #22541 - Manishearth:rollup, r=Gankro 1.0.0-alpha.2

Continued from #22520

1 files changed, 34 insertions, 0 deletions

diff --git a/src/test/run-pass/variance-intersection-of-ref-and-opt-ref.rs b/src/test/run-pass/variance-intersection-of-ref-and-opt-ref.rs
new file mode 100644
index 00000000000..948d68e0ccd
--- /dev/null
+++ b/src/test/run-pass/variance-intersection-of-ref-and-opt-ref.rs
@@ -0,0 +1,34 @@
+// Copyright 2015 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.
+
+// Elaborated version of the opening example from RFC 738. This failed
+// to compile before variance because invariance of `Option` prevented
+// us from approximating the lifetimes of `field1` and `field2` to a
+// common intersection.
+
+#![allow(dead_code)]
+
+struct List<'l> {
+    field1: &'l i32,
+    field2: Option<&'l i32>,
+}
+
+fn foo(field1: &i32, field2: Option<&i32>) -> i32 {
+    let list = List { field1: field1, field2: field2 };
+    *list.field1 + list.field2.cloned().unwrap_or(0)
+}
+
+fn main() {
+    let x = 22;
+    let y = Some(3);
+    let z = None;
+    assert_eq!(foo(&x, y.as_ref()), 25);
+    assert_eq!(foo(&x, z.as_ref()), 22);
+}