Actually use the inferred ClosureKind from signature inference in coroutine-closures

Author: compiler-errors

tests/pass/async-closure-captures.rs

@@ -88,4 +88,38 @@ async fn async_main() {
         };
         call_once(c).await;
     }
+
+    fn force_fnonce<T>(f: impl async FnOnce() -> T) -> impl async FnOnce() -> T {
+        f
+    }
+
+    // Capture something with `move`, but infer to `AsyncFnOnce`
+    {
+        let x = Hello(6);
+        let c = force_fnonce(async move || {
+            println!("{x:?}");
+        });
+        call_once(c).await;
+
+        let x = &Hello(7);
+        let c = force_fnonce(async move || {
+            println!("{x:?}");
+        });
+        call_once(c).await;
+    }
+
+    // Capture something by-ref, but infer to `AsyncFnOnce`
+    {
+        let x = Hello(8);
+        let c = force_fnonce(async || {
+            println!("{x:?}");
+        });
+        call_once(c).await;
+
+        let x = &Hello(9);
+        let c = force_fnonce(async || {
+            println!("{x:?}");
+        });
+        call_once(c).await;
+    }
 }

tests/pass/async-closure-captures.stderr

@@ -0,0 +1,31 @@
+error[E0597]: `x` does not live long enough
+  --> $DIR/async-closure-captures.rs:LL:CC
+   |
+LL |           let c = force_fnonce(async move || {
+   |  ____________________________________________-
+LL | |             println!("{x:?}");
+   | |                        ^ borrowed value does not live long enough
+LL | |         });
+   | |         --
+   | |         ||
+   | |         |`x` dropped here while still borrowed
+   | |_________|borrow later used here
+   |           value captured here by coroutine
+
+error[E0597]: `x` does not live long enough
+  --> $DIR/async-closure-captures.rs:LL:CC
+   |
+LL |           let c = force_fnonce(async move || {
+   |  ____________________________________________-
+LL | |             println!("{x:?}");
+   | |                        ^ borrowed value does not live long enough
+LL | |         });
+   | |         --
+   | |         ||
+   | |         |`x` dropped here while still borrowed
+   | |_________|borrow later used here
+   |           value captured here by coroutine
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0597`.