Two tests for rust-lang#22246

src/test/compile-fail/regions-assoc-type-outlives-container.rs

@@ -0,0 +1,91 @@
+// 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 we are imposing the requirement that every associated
+// type of a bound that appears in the where clause on a struct must
+// outlive the location in which the type appears. Issue #22246.
+
+#![allow(dead_code)]
+
+use std::mem::transmute;
+use std::ops::Deref;
+
+///////////////////////////////////////////////////////////////////////////
+
+pub trait TheTrait {
+    type TheAssocType;
+
+    fn dummy(&self) { }
+}
+
+pub struct TheType<'b> {
+    m: [fn(&'b()); 0]
+}
+
+impl<'b> TheTrait for TheType<'b> {
+    type TheAssocType = &'b ();
+}
+
+///////////////////////////////////////////////////////////////////////////
+
+pub struct WithAssoc<T:TheTrait> {
+    m: [T; 0]
+}
+
+pub struct WithoutAssoc<T> {
+    m: [T; 0]
+}
+
+fn with_assoc<'a,'b>() {
+    // For this type to be valid, the rules require that all
+    // associated types of traits that appear in `WithAssoc` must
+    // outlive 'a. In this case, that means TheType<'b>::TheAssocType,
+    // which is &'b (), must outlive 'a.
+
+    let _: &'a WithAssoc<TheType<'b>> = loop { }; //~ ERROR cannot infer
+}
+
+fn with_assoc1<'a,'b>() where 'b : 'a {
+    // For this type to be valid, the rules require that all
+    // associated types of traits that appear in `WithAssoc` must
+    // outlive 'a. In this case, that means TheType<'b>::TheAssocType,
+    // which is &'b (), must outlive 'a, so 'b : 'a must hold, and
+    // that is in the where clauses, so we're fine.
+
+    let _: &'a WithAssoc<TheType<'b>> = loop { };
+}
+
+fn without_assoc<'a,'b>() {
+    // Here there are no associated types and the `'b` appearing in
+    // `TheType<'b>` is purely covariant, so there is no requirement
+    // that `'b:'a` holds.
+
+    let _: &'a WithoutAssoc<TheType<'b>> = loop { };
+}
+
+fn call_with_assoc<'a,'b>() {
+    // As `with_assoc`, but just checking that we impose the same rule
+    // on the value supplied for the type argument, even when there is
+    // no data.
+
+    call::<&'a WithAssoc<TheType<'b>>>();
+    //~^ ERROR cannot infer
+}
+
+fn call_without_assoc<'a,'b>() {
+    // As `without_assoc`, but in a distinct scenario.
+
+    call::<&'a WithoutAssoc<TheType<'b>>>();
+}
+
+fn call<T>() { }
+
+fn main() {
+}

src/test/run-pass/regions-issue-22246.rs

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+// 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.
+
+// Regression test for issue #22246 -- we should be able to deduce
+// that `&'a B::Owned` implies that `B::Owned : 'a`.
+
+#![allow(dead_code)]
+
+use std::ops::Deref;
+
+pub trait ToOwned {
+    type Owned: Borrow<Self>;
+    fn to_owned(&self) -> Self::Owned;
+}
+
+pub trait Borrow<Borrowed> {
+    fn borrow(&self) -> &Borrowed;
+}
+
+pub struct Foo<B:ToOwned> {
+    owned: B::Owned
+}
+
+fn foo<B:ToOwned>(this: &Foo<B>) -> &B {
+    this.owned.borrow()
+}
+
+fn main() { }