From cd9f709a33b952d52c34e037dc13adfe0a3efb8d Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Mon, 6 Apr 2020 14:51:00 +0000
Subject: [PATCH] add nested regression test

---
 .../async-await/issues/issue-69307-nested.rs  | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 src/test/ui/async-await/issues/issue-69307-nested.rs

diff --git a/src/test/ui/async-await/issues/issue-69307-nested.rs b/src/test/ui/async-await/issues/issue-69307-nested.rs
new file mode 100644
index 000000000000..b7cdf3987f1c
--- /dev/null
+++ b/src/test/ui/async-await/issues/issue-69307-nested.rs
@@ -0,0 +1,30 @@
+// Regression test for #69307
+//
+// Having a `async { .. foo.await .. }` block appear inside of a `+=`
+// expression was causing an ICE due to a failure to save/restore
+// state in the AST numbering pass when entering a nested body.
+//
+// check-pass
+// edition:2018
+
+fn block_on<F>(_: F) -> usize {
+    0
+}
+
+fn main() {}
+
+async fn bar() {
+    let mut sum = 0;
+    sum += {
+        block_on(async {
+            baz().await;
+            let mut inner = 1;
+            inner += block_on(async {
+                baz().await;
+                0
+            })
+        })
+    };
+}
+
+async fn baz() {}