test derived from #74961

Author: dingxiangfei2009

src/test/ui/generator/yielding-in-match-guards.rs

@@ -0,0 +1,29 @@
+// check-pass
+// edition:2018
+
+// This test is derived from
+// https://github.com/rust-lang/rust/issues/74961#issuecomment-666893845
+// by @SNCPlay42
+
+// This test demonstrates that, in `async fn g()`,
+// indeed a temporary borrow `y` from `x` is live
+// while `f().await` is being evaluated.
+// Thus, `&'_ A` should be included in type signature
+// of the underlying generator.
+
+#[derive(PartialEq, Eq)]
+struct A;
+
+async fn f() -> A {
+    A
+}
+
+async fn g() {
+    let x = A;
+    match x {
+        y if f().await == y => {}
+        _ => {}
+    }
+}
+
+fn main() {}