auto merge of #20955 : nikomatsakis/rust/assoc-types-struct-field-access, r=nick29581

Normalize the types of fields we project out of a struct or tuple struct.
Fixes #20954.

r? @nick29581

src/test/run-pass/associated-types-struct-field-named.rs

@@ -0,0 +1,41 @@
+// 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 correctly normalize the type of a struct field
+// which has an associated type.
+
+pub trait UnifyKey {
+    type Value;
+}
+
+pub struct Node<K:UnifyKey> {
+    pub key: K,
+    pub value: K::Value,
+}
+
+fn foo<K : UnifyKey<Value=Option<V>>,V : Clone>(node: &Node<K>) -> Option<V> {
+    node.value.clone()
+}
+
+impl UnifyKey for i32 {
+    type Value = Option<u32>;
+}
+
+impl UnifyKey for u32 {
+    type Value = Option<i32>;
+}
+
+pub fn main() {
+    let node: Node<i32> = Node { key: 1, value: Some(22) };
+    assert_eq!(foo(&node), Some(22_u32));
+
+    let node: Node<u32> = Node { key: 1, value: Some(22) };
+    assert_eq!(foo(&node), Some(22_i32));
+}

src/test/run-pass/associated-types-struct-field-numbered.rs

@@ -0,0 +1,38 @@
+// 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 correctly normalize the type of a struct field
+// which has an associated type.
+
+pub trait UnifyKey {
+    type Value;
+}
+
+pub struct Node<K:UnifyKey>(K, K::Value);
+
+fn foo<K : UnifyKey<Value=Option<V>>,V : Clone>(node: &Node<K>) -> Option<V> {
+    node.1.clone()
+}
+
+impl UnifyKey for i32 {
+    type Value = Option<u32>;
+}
+
+impl UnifyKey for u32 {
+    type Value = Option<i32>;
+}
+
+pub fn main() {
+    let node: Node<i32> = Node(1, Some(22));
+    assert_eq!(foo(&node), Some(22_u32));
+
+    let node: Node<u32> = Node(1, Some(22));
+    assert_eq!(foo(&node), Some(22_i32));
+}

src/test/run-pass/trait-false-ambiguity-where-clause-builtin-bound.rs

@@ -0,0 +1,23 @@
+// 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 do not error out because of a (False) ambiguity
+// between the builtin rules for Sized and the where clause. Issue
+// #20959.
+
+fn foo<K>(x: Option<K>)
+    where Option<K> : Sized
+{
+    let _y = x;
+}
+
+fn main() {
+    foo(Some(22));
+}