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

Continued from #22520

1 files changed, 28 insertions, 0 deletions

diff --git a/src/test/run-pass/variance-vec-covariant.rs b/src/test/run-pass/variance-vec-covariant.rs
new file mode 100644
index 00000000000..caec6df5a4d
--- /dev/null
+++ b/src/test/run-pass/variance-vec-covariant.rs
@@ -0,0 +1,28 @@
+// 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.
+
+// Test that vec is now covariant in its argument type.
+
+#![allow(dead_code)]
+
+fn foo<'a,'b>(v1: Vec<&'a i32>, v2: Vec<&'b i32>) -> i32 {
+    bar(v1, v2).cloned().unwrap_or(0) // only type checks if we can intersect 'a and 'b
+}
+
+fn bar<'c>(v1: Vec<&'c i32>, v2: Vec<&'c i32>) -> Option<&'c i32> {
+    v1.get(0).cloned().or_else(|| v2.get(0).cloned())
+}
+
+fn main() {
+    let x = 22;
+    let y = 44;
+    assert_eq!(foo(vec![&x], vec![&y]), 22);
+    assert_eq!(foo(vec![&y], vec![&x]), 44);
+}