From 008d90a66a30bc8ff498f8ad47dea315c1853a75 Mon Sep 17 00:00:00 2001
From: csmoe <csmoe@msn.com>
Date: Sat, 16 May 2020 16:01:59 +0800
Subject: [PATCH] create error code E0754

---
 src/librustc_error_codes/error_codes.rs       |  1 +
 src/librustc_error_codes/error_codes/E0754.md | 29 +++++++++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 src/librustc_error_codes/error_codes/E0754.md

diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index e01412bc21c..52d40fd0f2f 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -435,6 +435,7 @@
 E0751: include_str!("./error_codes/E0751.md"),
 E0752: include_str!("./error_codes/E0752.md"),
 E0753: include_str!("./error_codes/E0753.md"),
+E0754: include_str!("./error_codes/E0754.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/src/librustc_error_codes/error_codes/E0754.md b/src/librustc_error_codes/error_codes/E0754.md
new file mode 100644
index 00000000000..e7cea982010
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0754.md
@@ -0,0 +1,29 @@
+`async fn`/`impl trait` return type cannot contain a projection or `Self` that references lifetimes from a parent scope.
+
+Erroneous code example:
+
+```compile_fail,E0754,edition2018
+struct S<'a>(&'a i32);
+
+impl<'a> S<'a> {
+    async fn new(i: &'a i32) -> Self {
+        S(&22)
+    }
+}
+```
+
+To fix this error we need to spell out `Self` to `S<'a>`:
+
+```edition2018
+struct S<'a>(&'a i32);
+
+impl<'a> S<'a> {
+    async fn new(i: &'a i32) -> S<'a> {
+        S(&22)
+    }
+}
+```
+
+This will be allowed at some point in the future, but the implementation is not yet complete. See the [issue-61949] for this limitation.
+
+[issue-61949]: https://github.com/rust-lang/rust/issues/61949
-- 
2.44.0