From cc54a1f9306c4453edbb3f914c0d010d3c2a21fe Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sun, 9 Aug 2020 13:13:56 +0200
Subject: [PATCH 1/2] Clean up E0749 explanation

---
 src/librustc_error_codes/error_codes/E0749.md | 23 +++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/librustc_error_codes/error_codes/E0749.md b/src/librustc_error_codes/error_codes/E0749.md
index 9eb8ee4e3fdf7..7a1a745b53c12 100644
--- a/src/librustc_error_codes/error_codes/E0749.md
+++ b/src/librustc_error_codes/error_codes/E0749.md
@@ -1,4 +1,19 @@
-Negative impls are not allowed to have any items. Negative impls
-declare that a trait is **not** implemented (and never will be) and
-hence there is no need to specify the values for trait methods or
-other items.
+An item was added on a negative impl.
+
+Erroneous code example:
+
+```compile_fail,E0749
+# #![feature(negative_impls)]
+trait MyTrait {
+    type Foo;
+}
+
+impl !MyTrait for u32 {
+    type Foo = i32; // error!
+}
+# fn main() {}
+```
+
+Negative impls are not allowed to have any items. Negative impls declare that a
+trait is **not** implemented (and never will be) and hence there is no need to
+specify the values for trait methods or other items.

From 4e78760137c8d6c314c4ecafd7e8240a89737b6e Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sun, 9 Aug 2020 13:15:33 +0200
Subject: [PATCH 2/2] Remove E0749 from untested error codes

---
 src/tools/tidy/src/error_codes_check.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tools/tidy/src/error_codes_check.rs b/src/tools/tidy/src/error_codes_check.rs
index 9c36d853ef78d..2fa0f12d7e8dc 100644
--- a/src/tools/tidy/src/error_codes_check.rs
+++ b/src/tools/tidy/src/error_codes_check.rs
@@ -16,7 +16,7 @@ const EXEMPTED_FROM_TEST: &[&str] = &[
 ];
 
 // Some error codes don't have any tests apparently...
-const IGNORE_EXPLANATION_CHECK: &[&str] = &["E0570", "E0601", "E0602", "E0639", "E0729", "E0749"];
+const IGNORE_EXPLANATION_CHECK: &[&str] = &["E0570", "E0601", "E0602", "E0639", "E0729"];
 
 fn check_error_code_explanation(
     f: &str,