Provide more context on derived obligation error primary label

Expand the primary span of E0277 when the immediate unmet bound is not what the user wrote:

```
error[E0277]: the trait bound `i32: Bar` is not satisfied
 --> f100.rs:6:6
  |
6 |     <i32 as Foo>::foo();
  |      ^^^ the trait `Bar` is not implemented for `i32`, which is required by `i32: Foo`
  |
help: this trait has no implementations, consider adding one
 --> f100.rs:2:1
  |
2 | trait Bar {}
  | ^^^^^^^^^
note: required for `i32` to implement `Foo`
 --> f100.rs:3:14
  |
3 | impl<T: Bar> Foo for T {}
  |         ---  ^^^     ^
  |         |
  |         unsatisfied trait bound introduced here
```

Fix #40120.

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/ui/async-await/debug-ice-attempted-to-add-with-overflow.stderr b/tests/ui/async-await/debug-ice-attempted-to-add-with-overflow.stderr
index 8c9d06c79ca..eab5bea681c 100644
--- a/tests/ui/async-await/debug-ice-attempted-to-add-with-overflow.stderr
+++ b/tests/ui/async-await/debug-ice-attempted-to-add-with-overflow.stderr
@@ -7,7 +7,7 @@ LL |     [0usize; 0xffff_ffff_ffff_ffff].await;
    |                                    |`[usize; usize::MAX]` is not a future
    |                                    help: remove the `.await`
    |
-   = help: the trait `Future` is not implemented for `[usize; usize::MAX]`
+   = help: the trait `Future` is not implemented for `[usize; usize::MAX]`, which is required by `[usize; usize::MAX]: IntoFuture`
    = note: [usize; usize::MAX] must be a future or must implement `IntoFuture` to be awaited
    = note: required for `[usize; usize::MAX]` to implement `IntoFuture`