From 7ee4f1da8c75b44501c01fb3e754c1732dad76c3 Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Tue, 20 Aug 2019 18:10:43 +0200
Subject: [PATCH] Allow 'default async fn' to parse.

---
 src/libsyntax/parse/parser/item.rs                 |  1 +
 .../ui/specialization/issue-63716-parse-async.rs   | 14 ++++++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 src/test/ui/specialization/issue-63716-parse-async.rs

diff --git a/src/libsyntax/parse/parser/item.rs b/src/libsyntax/parse/parser/item.rs
index 72819c9966035..03d7e92212382 100644
--- a/src/libsyntax/parse/parser/item.rs
+++ b/src/libsyntax/parse/parser/item.rs
@@ -825,6 +825,7 @@ impl<'a> Parser<'a> {
             self.is_keyword_ahead(1, &[
                 kw::Impl,
                 kw::Const,
+                kw::Async,
                 kw::Fn,
                 kw::Unsafe,
                 kw::Extern,
diff --git a/src/test/ui/specialization/issue-63716-parse-async.rs b/src/test/ui/specialization/issue-63716-parse-async.rs
new file mode 100644
index 0000000000000..c3764ffaab83f
--- /dev/null
+++ b/src/test/ui/specialization/issue-63716-parse-async.rs
@@ -0,0 +1,14 @@
+// Ensure that `default async fn` will parse.
+// See issue #63716 for details.
+
+// check-pass
+// edition:2018
+
+#![feature(specialization)]
+
+fn main() {}
+
+#[cfg(FALSE)]
+impl Foo for Bar {
+    default async fn baz() {}
+}