From 3ff10242fee5356cb4be91db6df2eee6b9a34089 Mon Sep 17 00:00:00 2001
From: Nadrieril <nadrieril+git@gmail.com>
Date: Thu, 18 Jan 2024 21:14:16 +0100
Subject: [PATCH] Test async fn

---
 .../120240-async-fn-never-arg.rs                 | 16 ++++++++++++++++
 .../120240-async-fn-never-arg.stderr             | 12 ++++++++++++
 .../ui/rfcs/rfc-0000-never_patterns/diverges.rs  |  6 ++++++
 3 files changed, 34 insertions(+)
 create mode 100644 tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.rs
 create mode 100644 tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.stderr

diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.rs b/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.rs
new file mode 100644
index 000000000000..9150c831c896
--- /dev/null
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.rs
@@ -0,0 +1,16 @@
+// edition: 2018
+// known-bug: #120240
+#![feature(never_patterns)]
+#![allow(incomplete_features)]
+
+fn main() {}
+
+enum Void {}
+
+// Divergence is not detected.
+async fn async_never(!: Void) -> ! {} // gives an error
+
+// Divergence is detected
+async fn async_let(x: Void) -> ! {
+    let ! = x;
+}
diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.stderr b/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.stderr
new file mode 100644
index 000000000000..fa71feee5f5a
--- /dev/null
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/120240-async-fn-never-arg.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/120240-async-fn-never-arg.rs:11:36
+   |
+LL | async fn async_never(!: Void) -> ! {} // gives an error
+   |                                    ^^ expected `!`, found `()`
+   |
+   = note:   expected type `!`
+           found unit type `()`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/diverges.rs b/tests/ui/rfcs/rfc-0000-never_patterns/diverges.rs
index 57151e246ff5..3783100b5028 100644
--- a/tests/ui/rfcs/rfc-0000-never_patterns/diverges.rs
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/diverges.rs
@@ -1,4 +1,5 @@
 // check-pass
+// edition: 2018
 #![feature(never_patterns)]
 #![allow(incomplete_features)]
 #![deny(unreachable_patterns)]
@@ -30,3 +31,8 @@ fn never_match() -> ! {
     // Ensures this typechecks because of divergence and not the type of the match expression.
     println!();
 }
+
+// Note: divergence is not detected for async fns when the `!` is in the argument (#120240).
+async fn async_let(x: Void) -> ! {
+    let ! = x;
+}