From 0696c28430c58508e40e027f565f48ff8e0c0b34 Mon Sep 17 00:00:00 2001
From: Stefano Buliani <stefano.buliani@gmail.com>
Date: Sat, 4 Sep 2021 11:49:13 -0700
Subject: [PATCH] test for issue #77175

---
 src/test/ui/lifetimes/issue-77175.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 src/test/ui/lifetimes/issue-77175.rs

diff --git a/src/test/ui/lifetimes/issue-77175.rs b/src/test/ui/lifetimes/issue-77175.rs
new file mode 100644
index 000000000000..2282752b6c1f
--- /dev/null
+++ b/src/test/ui/lifetimes/issue-77175.rs
@@ -0,0 +1,19 @@
+#[deny(single_use_lifetimes)]
+// edition:2018
+// check-pass
+
+// Prior to the fix, the compiler complained that the 'a lifetime was only used
+// once. This was obviously wrong since the lifetime is used twice: For the s3
+// parameter and the return type. The issue was caused by the compiler
+// desugaring the async function into a generator that uses only a single
+// lifetime, which then the validator complained about becauase of the
+// single_use_lifetimes constraints.
+async fn bar<'a>(s1: String, s2: &'_ str, s3: &'a str) -> &'a str {
+    s3
+}
+
+fn foo<'a>(s1: String, s2: &'_ str, s3: &'a str) -> &'a str {
+    s3
+}
+
+fn main() {}