Add drop tracking version of yielding-in-match-guard.rs

Author: eholk

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

@@ -0,0 +1,25 @@
+// build-pass
+// edition:2018
+// compile-flags: -Zdrop-tracking
+
+// This test is derived from
+// https://github.com/rust-lang/rust/issues/72651#issuecomment-668720468
+
+// This test demonstrates that, in `async fn g()`,
+// indeed a temporary borrow `y` from `x` is live
+// while `f().await` is being evaluated.
+// Thus, `&'_ u8` should be included in type signature
+// of the underlying generator.
+
+async fn f() -> u8 { 1 }
+
+async fn i(x: u8) {
+    match x {
+        y if f().await == y + 1 => (),
+        _ => (),
+    }
+}
+
+fn main() {
+    let _ = i(8);
+}