From 58089717b9f824ff278e37c4b1f29e7dc1fa47a9 Mon Sep 17 00:00:00 2001
From: Konrad Borowski <konrad@borowski.pw>
Date: Tue, 8 Oct 2019 12:19:00 +0200
Subject: [PATCH 1/3] Add ?Sized bound to a supertrait listing in E0038 error
 documentation

This example failed to compile because of implicit `Sized` bound
for `A` parameter that wasn't required by `Trait`.
---
 src/librustc/error_codes.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/librustc/error_codes.rs b/src/librustc/error_codes.rs
index 502172db91c9b..2de9cb5e9fb61 100644
--- a/src/librustc/error_codes.rs
+++ b/src/librustc/error_codes.rs
@@ -259,8 +259,8 @@ trait Foo {
 This is similar to the second sub-error, but subtler. It happens in situations
 like the following:
 
-```compile_fail
-trait Super<A> {}
+```
+trait Super<A: ?Sized> {}
 
 trait Trait: Super<Self> {
 }
@@ -275,8 +275,8 @@ impl Trait for Foo {}
 Here, the supertrait might have methods as follows:
 
 ```
-trait Super<A> {
-    fn get_a(&self) -> A; // note that this is object safe!
+trait Super<A: ?Sized> {
+    fn get_a(&self) -> &A; // note that this is object safe!
 }
 ```
 

From 7dc4bf4f935a929d1a9b8beb5d72ae1daa117f34 Mon Sep 17 00:00:00 2001
From: Konrad Borowski <konrad@borowski.pw>
Date: Wed, 9 Oct 2019 01:03:56 +0200
Subject: [PATCH 2/3] Change incorrect trait name in E0038 error documentation

---
 src/librustc/error_codes.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc/error_codes.rs b/src/librustc/error_codes.rs
index 2de9cb5e9fb61..caa7282c701cf 100644
--- a/src/librustc/error_codes.rs
+++ b/src/librustc/error_codes.rs
@@ -280,7 +280,7 @@ trait Super<A: ?Sized> {
 }
 ```
 
-If the trait `Foo` was deriving from something like `Super<String>` or
+If the trait `Trait` was deriving from something like `Super<String>` or
 `Super<T>` (where `Foo` itself is `Foo<T>`), this is okay, because given a type
 `get_a()` will definitely return an object of that type.
 

From 3f9d834fb3c32b67a5f368c8265a9ca6d83de7c3 Mon Sep 17 00:00:00 2001
From: Konrad Borowski <konrad@borowski.pw>
Date: Wed, 9 Oct 2019 12:33:24 +0200
Subject: [PATCH 3/3] Add failing example for Self in supertrait listing in
 E0038 documentation

---
 src/librustc/error_codes.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/librustc/error_codes.rs b/src/librustc/error_codes.rs
index caa7282c701cf..f3f1c9c6c7de4 100644
--- a/src/librustc/error_codes.rs
+++ b/src/librustc/error_codes.rs
@@ -259,7 +259,7 @@ trait Foo {
 This is similar to the second sub-error, but subtler. It happens in situations
 like the following:
 
-```
+```compile_fail,E0038
 trait Super<A: ?Sized> {}
 
 trait Trait: Super<Self> {
@@ -270,6 +270,10 @@ struct Foo;
 impl Super<Foo> for Foo{}
 
 impl Trait for Foo {}
+
+fn main() {
+    let x: Box<dyn Trait>;
+}
 ```
 
 Here, the supertrait might have methods as follows: