From 437c66cce5b13e18fa7ae09a4bb7fa9d86b01ec3 Mon Sep 17 00:00:00 2001
From: Lin Clark <lclark@mozilla.com>
Date: Wed, 30 Nov 2016 21:32:14 -0500
Subject: [PATCH 1/2] Add error explanation for E0328.

---
 src/librustc_typeck/diagnostics.rs | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/librustc_typeck/diagnostics.rs b/src/librustc_typeck/diagnostics.rs
index 1a971be64d819..1a87a5e709b21 100644
--- a/src/librustc_typeck/diagnostics.rs
+++ b/src/librustc_typeck/diagnostics.rs
@@ -3087,6 +3087,29 @@ impl Foo for Bar {
 ```
 "##,
 
+E0328: r##"
+The Unsize trait should not be implemented directly. All implementations of
+Unsize are provided automatically by the compiler.
+
+Here's an example of this error:
+
+```compile_fail,E0328
+#![feature(unsize)]
+
+use std::marker::Unsize;
+
+pub struct MyType;
+
+impl<T> Unsize<T> for MyType {}
+```
+
+If you are defining your own smart pointer type and would like to enable
+conversion from a sized to an unsized type with the [DST coercion system]
+(https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md), use
+[`CoerceUnsized`](https://doc.rust-lang.org/std/ops/trait.CoerceUnsized.html)
+instead.
+"##,
+
 E0329: r##"
 An attempt was made to access an associated constant through either a generic
 type parameter or `Self`. This is not supported yet. An example causing this
@@ -4195,7 +4218,6 @@ register_diagnostics! {
 //  E0249,
 //  E0319, // trait impls for defaulted traits allowed just for structs/enums
     E0320, // recursive overflow during dropck
-    E0328, // cannot implement Unsize explicitly
 //  E0372, // coherence not object safe
     E0377, // the trait `CoerceUnsized` may only be implemented for a coercion
            // between structures with the same definition

From ac28aba886c92ff3b81347425c7b09cdfaf88ec8 Mon Sep 17 00:00:00 2001
From: Lin Clark <lclark@mozilla.com>
Date: Thu, 5 Jan 2017 13:42:22 -0500
Subject: [PATCH 2/2] added how to fix the problem block

---
 src/librustc_typeck/diagnostics.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/librustc_typeck/diagnostics.rs b/src/librustc_typeck/diagnostics.rs
index 1a87a5e709b21..28f4cacd635ca 100644
--- a/src/librustc_typeck/diagnostics.rs
+++ b/src/librustc_typeck/diagnostics.rs
@@ -3091,7 +3091,7 @@ E0328: r##"
 The Unsize trait should not be implemented directly. All implementations of
 Unsize are provided automatically by the compiler.
 
-Here's an example of this error:
+Erroneous code example:
 
 ```compile_fail,E0328
 #![feature(unsize)]
@@ -3108,6 +3108,19 @@ conversion from a sized to an unsized type with the [DST coercion system]
 (https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md), use
 [`CoerceUnsized`](https://doc.rust-lang.org/std/ops/trait.CoerceUnsized.html)
 instead.
+
+```
+#![feature(coerce_unsized)]
+
+use std::ops::CoerceUnsized;
+
+pub struct MyType<T: ?Sized> {
+    field_with_unsized_type: T,
+}
+
+impl<T, U> CoerceUnsized<MyType<U>> for MyType<T>
+    where T: CoerceUnsized<U> {}
+```
 "##,
 
 E0329: r##"