From d1db077e067b00c4733512dd23f8b144a760f367 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sat, 12 Oct 2019 14:48:20 +0200
Subject: [PATCH 1/2] Add long error explanation for E0575

---
 src/librustc_resolve/error_codes.rs | 54 ++++++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/librustc_resolve/error_codes.rs b/src/librustc_resolve/error_codes.rs
index ab3d95dd8edfe..8ccb27078d569 100644
--- a/src/librustc_resolve/error_codes.rs
+++ b/src/librustc_resolve/error_codes.rs
@@ -1735,6 +1735,59 @@ match eco {
 ```
 "##,
 
+E0575: r##"
+Something other than a type or an associated type was given.
+
+Erroneous code example:
+
+```compile_fail,E0575
+enum Rick { Morty }
+
+let _: <u8 as Rick>::Morty; // error!
+
+trait Age {
+    type Empire;
+    fn Mythology() {}
+}
+
+impl Age for u8 {
+    type Empire = u16;
+}
+
+let _: <u8 as Age>::Mythology; // error!
+```
+
+In both cases, we're declaring a variable (called `_`) and we're giving it a
+type. However, `<u8 as Rick>::Morty` and `<u8 as Age>::Mythology` aren't types,
+therefore the compiler throws an error.
+
+`<u8 as Rick>::Morty` is an enum variant, you cannot use a variant as a type,
+you have to use the enum directly:
+
+```
+enum Rick { Morty }
+
+let _: Rick; // ok!
+```
+
+`<u8 as Age>::Mythology` is a trait method, which is definitely not a type.
+However, the `Age` trait provides an associated type `Empire` which can be
+used as a type:
+
+```
+trait Age {
+    type Empire;
+    fn Mythology() {}
+}
+
+impl Age for u8 {
+    type Empire = u16;
+}
+
+let _: <u8 as Age>::Empire; // ok!
+```
+"##,
+
 E0603: r##"
 A private item was used outside its scope.
 
@@ -1862,7 +1915,6 @@ struct Foo<X = Box<Self>> {
 //  E0427, merged into 530
 //  E0467, removed
 //  E0470, removed
-    E0575,
     E0576,
     E0577,
     E0578,

From 21d9258909d131898bdd9d69bc9da8be3b31db9a Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sat, 12 Oct 2019 14:48:28 +0200
Subject: [PATCH 2/2] Update ui tests

---
 src/test/ui/ufcs/ufcs-partially-resolved.stderr | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/ui/ufcs/ufcs-partially-resolved.stderr b/src/test/ui/ufcs/ufcs-partially-resolved.stderr
index 5ee8adaaf270f..39752f66b9d65 100644
--- a/src/test/ui/ufcs/ufcs-partially-resolved.stderr
+++ b/src/test/ui/ufcs/ufcs-partially-resolved.stderr
@@ -200,5 +200,5 @@ LL |     <u8 as Dr>::X::N;
 
 error: aborting due to 32 previous errors
 
-Some errors have detailed explanations: E0223, E0433, E0599.
+Some errors have detailed explanations: E0223, E0433, E0575, E0599.
 For more information about an error, try `rustc --explain E0223`.