Auto merge of #27096 - apasel422:issue-26217, r=nikomatsakis

closes #26217

r? @nikomatsakis

src/test/run-pass/hrtb-type-outlives.rs

@@ -0,0 +1,55 @@
+// Copyright 2014 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 what happens when a HR obligation is applied to an impl with
+// "outlives" bounds. Currently we're pretty conservative here; this
+// will probably improve in time.
+
+trait Foo<X> {
+    fn foo(&self, x: X) { }
+}
+
+fn want_foo<T>()
+    where T : for<'a> Foo<&'a isize>
+{
+}
+
+///////////////////////////////////////////////////////////////////////////
+// Expressed as a where clause
+
+struct SomeStruct<X> {
+    x: X
+}
+
+impl<'a,X> Foo<&'a isize> for SomeStruct<X>
+    where X : 'a
+{
+}
+
+fn one() {
+    want_foo::<SomeStruct<usize>>();
+}
+
+///////////////////////////////////////////////////////////////////////////
+// Expressed as shorthand
+
+struct AnotherStruct<X> {
+    x: X
+}
+
+impl<'a,X:'a> Foo<&'a isize> for AnotherStruct<X>
+{
+}
+
+fn two() {
+    want_foo::<AnotherStruct<usize>>();
+}
+
+fn main() { }