Auto merge of rust-lang#116360 - compiler-errors:async-span, r=oli-obk

Point to full `async fn` for future

Semi-follow-up to rust-lang#116296 (comment)

cc `@asquared31415`

Author: bors

tests/ui/crashes/ice-10645.stderr

@@ -1,8 +1,8 @@
 warning: future cannot be sent between threads safely
-  --> $DIR/ice-10645.rs:5:35
+  --> $DIR/ice-10645.rs:5:1
    |
 LL | pub async fn bar<'a, T: 'a>(_: T) {}
-   |                                   ^ future returned by `bar` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `bar` is not `Send`
    |
 note: captured value is not `Send`
   --> $DIR/ice-10645.rs:5:29

tests/ui/future_not_send.stderr

@@ -1,8 +1,8 @@
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:7:62
+  --> $DIR/future_not_send.rs:7:1
    |
 LL | async fn private_future(rc: Rc<[u8]>, cell: &Cell<usize>) -> bool {
-   |                                                              ^^^^ future returned by `private_future` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `private_future` is not `Send`
    |
 note: future is not `Send` as this value is used across an await
   --> $DIR/future_not_send.rs:9:20
@@ -23,10 +23,10 @@ LL | async fn private_future(rc: Rc<[u8]>, cell: &Cell<usize>) -> bool {
    = help: to override `-D warnings` add `#[allow(clippy::future_not_send)]`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:12:42
+  --> $DIR/future_not_send.rs:12:1
    |
 LL | pub async fn public_future(rc: Rc<[u8]>) {
-   |                                          ^ future returned by `public_future` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `public_future` is not `Send`
    |
 note: future is not `Send` as this value is used across an await
   --> $DIR/future_not_send.rs:14:20
@@ -39,10 +39,10 @@ LL |     async { true }.await;
    = note: `std::rc::Rc<[u8]>` doesn't implement `std::marker::Send`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:21:63
+  --> $DIR/future_not_send.rs:21:1
    |
 LL | async fn private_future2(rc: Rc<[u8]>, cell: &Cell<usize>) -> bool {
-   |                                                               ^^^^ future returned by `private_future2` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `private_future2` is not `Send`
    |
 note: captured value is not `Send`
   --> $DIR/future_not_send.rs:21:26
@@ -58,10 +58,10 @@ LL | async fn private_future2(rc: Rc<[u8]>, cell: &Cell<usize>) -> bool {
    = note: `std::cell::Cell<usize>` doesn't implement `std::marker::Sync`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:26:43
+  --> $DIR/future_not_send.rs:26:1
    |
 LL | pub async fn public_future2(rc: Rc<[u8]>) {}
-   |                                           ^ future returned by `public_future2` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `public_future2` is not `Send`
    |
 note: captured value is not `Send`
   --> $DIR/future_not_send.rs:26:29
@@ -71,10 +71,10 @@ LL | pub async fn public_future2(rc: Rc<[u8]>) {}
    = note: `std::rc::Rc<[u8]>` doesn't implement `std::marker::Send`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:38:39
+  --> $DIR/future_not_send.rs:38:5
    |
 LL |     async fn private_future(&self) -> usize {
-   |                                       ^^^^^ future returned by `private_future` is not `Send`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `private_future` is not `Send`
    |
 note: future is not `Send` as this value is used across an await
   --> $DIR/future_not_send.rs:40:24
@@ -87,10 +87,10 @@ LL |         async { true }.await;
    = note: `std::rc::Rc<[u8]>` doesn't implement `std::marker::Sync`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:44:39
+  --> $DIR/future_not_send.rs:44:5
    |
 LL |     pub async fn public_future(&self) {
-   |                                       ^ future returned by `public_future` is not `Send`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `public_future` is not `Send`
    |
 note: captured value is not `Send` because `&` references cannot be sent unless their referent is `Sync`
   --> $DIR/future_not_send.rs:44:32
@@ -100,10 +100,13 @@ LL |     pub async fn public_future(&self) {
    = note: `std::rc::Rc<[u8]>` doesn't implement `std::marker::Sync`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:55:37
+  --> $DIR/future_not_send.rs:55:1
    |
-LL | async fn generic_future<T>(t: T) -> T
-   |                                     ^ future returned by `generic_future` is not `Send`
+LL | / async fn generic_future<T>(t: T) -> T
+LL | |
+LL | | where
+LL | |     T: Send,
+   | |____________^ future returned by `generic_future` is not `Send`
    |
 note: future is not `Send` as this value is used across an await
   --> $DIR/future_not_send.rs:61:20
@@ -115,10 +118,10 @@ LL |     async { true }.await;
    = note: `T` doesn't implement `std::marker::Sync`
 
 error: future cannot be sent between threads safely
-  --> $DIR/future_not_send.rs:73:34
+  --> $DIR/future_not_send.rs:73:1
    |
 LL | async fn unclear_future<T>(t: T) {}
-   |                                  ^ future returned by `unclear_future` is not `Send`
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ future returned by `unclear_future` is not `Send`
    |
 note: captured value is not `Send`
   --> $DIR/future_not_send.rs:73:28