Update async-fn-nonsend.rs

The previous commit made the non_sync_with_method_call case pass due to
the await being unreachable. Unfortunately, this isn't actually the
behavior the test was verifying. This change lifts the panic into a
helper function so that the generator analysis still thinks the await
is reachable, and therefore we preserve the same testing behavior.

Author: eholk

src/test/ui/async-await/async-fn-nonsend.rs

@@ -35,14 +35,26 @@ async fn non_send_temporary_in_match() {
     }
 }
 
+fn get_formatter() -> std::fmt::Formatter<'static> {
+    panic!()
+}
+
 async fn non_sync_with_method_call() {
+    let f: &mut std::fmt::Formatter = &mut get_formatter();
+    // It would by nice for this to work.
+    if non_sync().fmt(f).unwrap() == () {
+        fut().await;
+    }
+}
+
+async fn non_sync_with_method_call_panic() {
     let f: &mut std::fmt::Formatter = panic!();
     if non_sync().fmt(f).unwrap() == () {
         fut().await;
     }
 }
 
-async fn non_sync_with_infinite_loop() {
+async fn non_sync_with_method_call_infinite_loop() {
     let f: &mut std::fmt::Formatter = loop {};
     if non_sync().fmt(f).unwrap() == () {
         fut().await;
@@ -56,5 +68,7 @@ pub fn pass_assert() {
     assert_send(non_send_temporary_in_match());
     //~^ ERROR future cannot be sent between threads safely
     assert_send(non_sync_with_method_call());
-    assert_send(non_sync_with_infinite_loop());
+    //~^ ERROR future cannot be sent between threads safely
+    assert_send(non_sync_with_method_call_panic());
+    assert_send(non_sync_with_method_call_infinite_loop());
 }

src/test/ui/async-await/async-fn-nonsend.stderr

@@ -1,5 +1,5 @@
 error: future cannot be sent between threads safely
-  --> $DIR/async-fn-nonsend.rs:56:17
+  --> $DIR/async-fn-nonsend.rs:68:17
    |
 LL |     assert_send(non_send_temporary_in_match());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `non_send_temporary_in_match` is not `Send`
@@ -16,10 +16,34 @@ LL |         Some(_) => fut().await,
 LL | }
    | - `Some(non_send())` is later dropped here
 note: required by a bound in `assert_send`
-  --> $DIR/async-fn-nonsend.rs:52:24
+  --> $DIR/async-fn-nonsend.rs:64:24
    |
 LL | fn assert_send(_: impl Send) {}
    |                        ^^^^ required by this bound in `assert_send`
 
-error: aborting due to previous error
+error: future cannot be sent between threads safely
+  --> $DIR/async-fn-nonsend.rs:70:17
+   |
+LL |     assert_send(non_sync_with_method_call());
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `non_sync_with_method_call` is not `Send`
+   |
+   = help: the trait `Send` is not implemented for `dyn std::fmt::Write`
+note: future is not `Send` as this value is used across an await
+  --> $DIR/async-fn-nonsend.rs:46:14
+   |
+LL |     let f: &mut std::fmt::Formatter = &mut get_formatter();
+   |                                            --------------- has type `Formatter<'_>` which is not `Send`
+...
+LL |         fut().await;
+   |              ^^^^^^ await occurs here, with `get_formatter()` maybe used later
+LL |     }
+LL | }
+   | - `get_formatter()` is later dropped here
+note: required by a bound in `assert_send`
+  --> $DIR/async-fn-nonsend.rs:64:24
+   |
+LL | fn assert_send(_: impl Send) {}
+   |                        ^^^^ required by this bound in `assert_send`
+
+error: aborting due to 2 previous errors