Implement the rules for RFC 599, and add various tests.

Fixes #22211.

src/test/run-pass/object-lifetime-default-from-ref-struct.rs

@@ -0,0 +1,47 @@
+// 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 the lifetime of the enclosing `&` is used for the object
+// lifetime bound.
+
+#![allow(dead_code)]
+
+trait Test {
+    fn foo(&self) { }
+}
+
+struct Ref<'a,T:'a+?Sized> {
+    r: &'a T
+}
+
+struct SomeStruct<'a> {
+    t: Ref<'a,Test>,
+    u: Ref<'a,Test+'a>,
+}
+
+fn a<'a>(t: Ref<'a,Test>, mut ss: SomeStruct<'a>) {
+    ss.t = t;
+}
+
+fn b<'a>(t: Ref<'a,Test>, mut ss: SomeStruct<'a>) {
+    ss.u = t;
+}
+
+fn c<'a>(t: Ref<'a,Test+'a>, mut ss: SomeStruct<'a>) {
+    ss.t = t;
+}
+
+fn d<'a>(t: Ref<'a,Test+'a>, mut ss: SomeStruct<'a>) {
+    ss.u = t;
+}
+
+
+fn main() {
+}