Don't double-annotate the same Span

Author: tmandry

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

@@ -1274,7 +1274,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 "await occurs here".to_string(),
             );
 
-            push_target_span(&mut span);
+            if target_span != await_span {
+                push_target_span(&mut span);
+            }
 
             err.span_note(
                 span,

src/test/ui/async-await/issue-68112.rs

@@ -35,6 +35,15 @@ fn test1() {
     //~^ ERROR future cannot be sent between threads
 }
 
+fn test1_no_let() {
+    let send_fut = async {
+        let _ = make_non_send_future1().await;
+        ready(0).await;
+    };
+    require_send(send_fut);
+    //~^ ERROR future cannot be sent between threads
+}
+
 async fn ready2<T>(t: T) -> T { t }
 fn make_non_send_future2() -> impl Future<Output = Arc<RefCell<i32>>> {
     ready2(Arc::new(RefCell::new(0)))

src/test/ui/async-await/issue-68112.stderr

@@ -16,8 +16,24 @@ LL |         let non_send_fut = make_non_send_future1();
 LL |         let _ = non_send_fut.await;
    |                 ^^^^^^^^^^^^ await occurs here
 
+error: future cannot be sent between threads safely
+  --> $DIR/issue-68112.rs:43:5
+   |
+LL | fn require_send(_: impl Send) {}
+   |    ------------         ---- required by this bound in `require_send`
+...
+LL |     require_send(send_fut);
+   |     ^^^^^^^^^^^^ future created by async block is not `Send`
+   |
+   = help: the trait `std::marker::Sync` is not implemented for `std::cell::RefCell<i32>`
+note: future is not `Send` as this value is used in an await
+  --> $DIR/issue-68112.rs:40:17
+   |
+LL |         let _ = make_non_send_future1().await;
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^ await occurs here
+
 error[E0277]: `std::cell::RefCell<i32>` cannot be shared between threads safely
-  --> $DIR/issue-68112.rs:49:5
+  --> $DIR/issue-68112.rs:58:5
    |
 LL | fn require_send(_: impl Send) {}
    |    ------------         ---- required by this bound in `require_send`
@@ -27,16 +43,16 @@ LL |     require_send(send_fut);
    |
    = help: the trait `std::marker::Sync` is not implemented for `std::cell::RefCell<i32>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `std::sync::Arc<std::cell::RefCell<i32>>`
-   = note: required because it appears within the type `[static generator@$DIR/issue-68112.rs:38:31: 38:36 t:std::sync::Arc<std::cell::RefCell<i32>> {}]`
-   = note: required because it appears within the type `std::future::from_generator::GenFuture<[static generator@$DIR/issue-68112.rs:38:31: 38:36 t:std::sync::Arc<std::cell::RefCell<i32>> {}]>`
+   = note: required because it appears within the type `[static generator@$DIR/issue-68112.rs:47:31: 47:36 t:std::sync::Arc<std::cell::RefCell<i32>> {}]`
+   = note: required because it appears within the type `std::future::from_generator::GenFuture<[static generator@$DIR/issue-68112.rs:47:31: 47:36 t:std::sync::Arc<std::cell::RefCell<i32>> {}]>`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `{std::future::ResumeTy, impl std::future::Future, (), i32, Ready<i32>}`
-   = note: required because it appears within the type `[static generator@$DIR/issue-68112.rs:44:26: 48:6 {std::future::ResumeTy, impl std::future::Future, (), i32, Ready<i32>}]`
-   = note: required because it appears within the type `std::future::from_generator::GenFuture<[static generator@$DIR/issue-68112.rs:44:26: 48:6 {std::future::ResumeTy, impl std::future::Future, (), i32, Ready<i32>}]>`
+   = note: required because it appears within the type `[static generator@$DIR/issue-68112.rs:53:26: 57:6 {std::future::ResumeTy, impl std::future::Future, (), i32, Ready<i32>}]`
+   = note: required because it appears within the type `std::future::from_generator::GenFuture<[static generator@$DIR/issue-68112.rs:53:26: 57:6 {std::future::ResumeTy, impl std::future::Future, (), i32, Ready<i32>}]>`
    = note: required because it appears within the type `impl std::future::Future`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0277`.