Point at type that doesn't implement needed trait

```
error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied
  --> $DIR/bad-question-mark-on-trait-object.rs:7:13
   |
LL | fn foo() -> Result<(), Box<dyn std::error::Error>> {
   |             -------------------------------------- required `E: std::error::Error` because of this
LL |     Ok(bar()?)
   |        -----^ the trait `std::error::Error` is not implemented for `E`
   |        |
   |        this has type `Result<_, E>`
   |
note: `E` needs to implement `std::error::Error`
  --> $DIR/bad-question-mark-on-trait-object.rs:1:1
   |
LL | struct E;
   | ^^^^^^^^
   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
   = note: required for `Box<dyn std::error::Error>` to implement `From<E>`

error[E0277]: `?` couldn't convert the error to `X`
  --> $DIR/bad-question-mark-on-trait-object.rs:18:13
   |
LL | fn bat() -> Result<(), X> {
   |             ------------- expected `X` because of this
LL |     Ok(bar()?)
   |        -----^ the trait `From<E>` is not implemented for `X`
   |        |
   |        this can't be annotated with `?` because it has type `Result<_, E>`
   |
note: `X` needs to implement `From<E>`
  --> $DIR/bad-question-mark-on-trait-object.rs:4:1
   |
LL | struct X;
   | ^^^^^^^^
note: alternatively, `E` needs to implement `Into<X>`
  --> $DIR/bad-question-mark-on-trait-object.rs:1:1
   |
LL | struct E;
   | ^^^^^^^^
   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
```

2 files changed, 20 insertions, 3 deletions

diff --git a/tests/ui/try-trait/bad-question-mark-on-trait-object.rs b/tests/ui/try-trait/bad-question-mark-on-trait-object.rs
index 9efac78b3d7..2a0d14b1750 100644
--- a/tests/ui/try-trait/bad-question-mark-on-trait-object.rs
+++ b/tests/ui/try-trait/bad-question-mark-on-trait-object.rs
@@ -1,5 +1,7 @@
 struct E;
-struct X;
+//~^ NOTE `E` needs to implement `std::error::Error`
+//~| NOTE alternatively, `E` needs to implement `Into<X>`
+struct X; //~ NOTE `X` needs to implement `From<E>`
 
 fn foo() -> Result<(), Box<dyn std::error::Error>> { //~ NOTE required `E: std::error::Error` because of this
     Ok(bar()?)
diff --git a/tests/ui/try-trait/bad-question-mark-on-trait-object.stderr b/tests/ui/try-trait/bad-question-mark-on-trait-object.stderr
index adebc16915d..dd380850c9e 100644
--- a/tests/ui/try-trait/bad-question-mark-on-trait-object.stderr
+++ b/tests/ui/try-trait/bad-question-mark-on-trait-object.stderr
@@ -1,5 +1,5 @@
 error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied
-  --> $DIR/bad-question-mark-on-trait-object.rs:5:13
+  --> $DIR/bad-question-mark-on-trait-object.rs:7:13
    |
 LL | fn foo() -> Result<(), Box<dyn std::error::Error>> {
    |             -------------------------------------- required `E: std::error::Error` because of this
@@ -8,11 +8,16 @@ LL |     Ok(bar()?)
    |        |
    |        this has type `Result<_, E>`
    |
+note: `E` needs to implement `std::error::Error`
+  --> $DIR/bad-question-mark-on-trait-object.rs:1:1
+   |
+LL | struct E;
+   | ^^^^^^^^
    = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
    = note: required for `Box<dyn std::error::Error>` to implement `From<E>`
 
 error[E0277]: `?` couldn't convert the error to `X`
-  --> $DIR/bad-question-mark-on-trait-object.rs:16:13
+  --> $DIR/bad-question-mark-on-trait-object.rs:18:13
    |
 LL | fn bat() -> Result<(), X> {
    |             ------------- expected `X` because of this
@@ -21,6 +26,16 @@ LL |     Ok(bar()?)
    |        |
    |        this can't be annotated with `?` because it has type `Result<_, E>`
    |
+note: `X` needs to implement `From<E>`
+  --> $DIR/bad-question-mark-on-trait-object.rs:4:1
+   |
+LL | struct X;
+   | ^^^^^^^^
+note: alternatively, `E` needs to implement `Into<X>`
+  --> $DIR/bad-question-mark-on-trait-object.rs:1:1
+   |
+LL | struct E;
+   | ^^^^^^^^
    = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
 
 error: aborting due to 2 previous errors