Tweak E0277 when predicate comes indirectly from ?

When a `?` operation requires an `Into` conversion with additional bounds (like having a concrete error but wanting to convert to a trait object), we handle it speficically and provide the same kind of information we give other `?` related errors.

```
error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied
  --> $DIR/bad-question-mark-on-trait-object.rs:5:13
   |
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`
   |
   = 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>`
```

Avoid talking about `FromResidual` when other more relevant information is being given, particularly from `rust_on_unimplemented`.

tests/ui/async-await/issue-84841.stderr

@@ -17,8 +17,6 @@ LL | |     test()?;
 ...  |
 LL | | }
    | |_- this function should return `Result` or `Option` to accept `?`
-   |
-   = help: the trait `FromResidual<_>` is not implemented for `()`
 
 error: aborting due to 2 previous errors
 

tests/ui/async-await/try-on-option-in-async.stderr

@@ -6,8 +6,6 @@ LL |     async {
 LL |         let x: Option<u32> = None;
 LL |         x?;
    |          ^ cannot use the `?` operator in an async block that returns `{integer}`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `{integer}`
 
 error[E0277]: the `?` operator can only be used in an async closure that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option-in-async.rs:16:10
@@ -20,8 +18,6 @@ LL | |         x?;
 LL | |         22_u32
 LL | |     };
    | |_____- this function should return `Result` or `Option` to accept `?`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
 
 error[E0277]: the `?` operator can only be used in an async function that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option-in-async.rs:25:6
@@ -34,8 +30,6 @@ LL | |     x?;
 LL | |     22
 LL | | }
    | |_- this function should return `Result` or `Option` to accept `?`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
 
 error: aborting due to 3 previous errors
 

tests/ui/return/return-from-residual-sugg-issue-125997.stderr

@@ -6,7 +6,6 @@ LL | fn test1() {
 LL |     let mut _file = File::create("foo.txt")?;
    |                                            ^ cannot use the `?` operator in a function that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~ fn test1() -> Result<(), Box<dyn std::error::Error>> {
@@ -23,7 +22,6 @@ LL | fn test2() {
 LL |     let mut _file = File::create("foo.txt")?;
    |                                            ^ cannot use the `?` operator in a function that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~ fn test2() -> Result<(), Box<dyn std::error::Error>> {
@@ -41,7 +39,6 @@ LL |     fn test4(&self) {
 LL |         let mut _file = File::create("foo.txt")?;
    |                                                ^ cannot use the `?` operator in a method that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~     fn test4(&self) -> Result<(), Box<dyn std::error::Error>> {
@@ -59,7 +56,6 @@ LL |     fn test5(&self) {
 LL |         let mut _file = File::create("foo.txt")?;
    |                                                ^ cannot use the `?` operator in a method that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~     fn test5(&self) -> Result<(), Box<dyn std::error::Error>> {
@@ -78,7 +74,6 @@ LL | fn main() {
 LL |     let mut _file = File::create("foo.txt")?;
    |                                            ^ cannot use the `?` operator in a function that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> {
@@ -99,7 +94,6 @@ LL |             let mut _file = File::create("foo.txt")?;
 LL |     mac!();
    |     ------ in this macro invocation
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
    = note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: consider adding return type
    |

tests/ui/try-trait/bad-interconversion.stderr

@@ -20,9 +20,6 @@ LL | fn option_to_result() -> Result<u64, String> {
    | -------------------------------------------- this function returns a `Result`
 LL |     Some(3)?;
    |            ^ use `.ok_or(...)?` to provide an error compatible with `Result<u64, String>`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<u64, String>`
-   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Result`s in a function that returns `Result`
   --> $DIR/bad-interconversion.rs:15:31
@@ -31,9 +28,6 @@ LL | fn control_flow_to_result() -> Result<u64, String> {
    | -------------------------------------------------- this function returns a `Result`
 LL |     Ok(ControlFlow::Break(123)?)
    |                               ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Result<u64, String>`
-   |
-   = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Result<u64, String>`
-   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
   --> $DIR/bad-interconversion.rs:20:22
@@ -42,9 +36,6 @@ LL | fn result_to_option() -> Option<u16> {
    | ------------------------------------ this function returns an `Option`
 LL |     Some(Err("hello")?)
    |                      ^ use `.ok()?` if you want to discard the `Result<Infallible, &str>` error information
-   |
-   = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `Option<u16>`
-   = help: the trait `FromResidual<Option<Infallible>>` is implemented for `Option<T>`
 
 error[E0277]: the `?` operator can only be used on `Option`s in a function that returns `Option`
   --> $DIR/bad-interconversion.rs:25:33
@@ -53,9 +44,6 @@ LL | fn control_flow_to_option() -> Option<u64> {
    | ------------------------------------------ this function returns an `Option`
 LL |     Some(ControlFlow::Break(123)?)
    |                                 ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Option<u64>`
-   |
-   = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Option<u64>`
-   = help: the trait `FromResidual<Option<Infallible>>` is implemented for `Option<T>`
 
 error[E0277]: the `?` operator can only be used on `ControlFlow`s in a function that returns `ControlFlow`
   --> $DIR/bad-interconversion.rs:30:39

tests/ui/try-trait/bad-question-mark-on-trait-object.rs

@@ -0,0 +1,26 @@
+struct E;
+struct X;
+
+fn foo() -> Result<(), Box<dyn std::error::Error>> { //~ NOTE required `E: std::error::Error` because of this
+    Ok(bar()?)
+    //~^ ERROR `?` couldn't convert the error: `E: std::error::Error` is not satisfied
+    //~| NOTE the trait `std::error::Error` is not implemented for `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>`
+    //~| NOTE in this expansion
+    //~| NOTE in this expansion
+    //~| NOTE in this expansion
+}
+fn bat() -> Result<(), X> { //~ NOTE expected `X` because of this
+    Ok(bar()?)
+    //~^ ERROR `?` couldn't convert the error to `X`
+    //~| NOTE the trait `From<E>` is not implemented for `X`
+    //~| NOTE this can't be annotated with `?` because it has type `Result<_, E>`
+    //~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
+    //~| NOTE in this expansion
+    //~| NOTE in this expansion
+}
+fn bar() -> Result<(), E> {
+    Err(E)
+}
+fn main() {}

tests/ui/try-trait/bad-question-mark-on-trait-object.stderr

@@ -0,0 +1,26 @@
+error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied
+  --> $DIR/bad-question-mark-on-trait-object.rs:5:13
+   |
+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`
+   |
+   = 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:15:13
+   |
+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: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/try-trait/option-to-result.stderr

@@ -6,9 +6,6 @@ LL | fn test_result() -> Result<(),()> {
 LL |     let a:Option<()> = Some(());
 LL |     a?;
    |      ^ use `.ok_or(...)?` to provide an error compatible with `Result<(), ()>`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<(), ()>`
-   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
   --> $DIR/option-to-result.rs:11:6
@@ -18,9 +15,6 @@ LL | fn test_option() -> Option<i32>{
 LL |     let a:Result<i32, i32> = Ok(5);
 LL |     a?;
    |      ^ use `.ok()?` if you want to discard the `Result<Infallible, i32>` error information
-   |
-   = help: the trait `FromResidual<Result<Infallible, i32>>` is not implemented for `Option<i32>`
-   = help: the trait `FromResidual<Option<Infallible>>` is implemented for `Option<T>`
 
 error: aborting due to 2 previous errors
 

tests/ui/try-trait/try-on-option-diagnostics.stderr

@@ -6,8 +6,6 @@ LL | fn a_function() -> u32 {
 LL |     let x: Option<u32> = None;
 LL |     x?;
    |      ^ cannot use the `?` operator in a function that returns `u32`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
 
 error[E0277]: the `?` operator can only be used in a closure that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option-diagnostics.rs:14:10
@@ -17,8 +15,6 @@ LL |     let a_closure = || {
 LL |         let x: Option<u32> = None;
 LL |         x?;
    |          ^ cannot use the `?` operator in a closure that returns `{integer}`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `{integer}`
 
 error[E0277]: the `?` operator can only be used in a method that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option-diagnostics.rs:26:14
@@ -28,8 +24,6 @@ LL |         fn a_method() {
 LL |             let x: Option<u32> = None;
 LL |             x?;
    |              ^ cannot use the `?` operator in a method that returns `()`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `()`
 
 error[E0277]: the `?` operator can only be used in a trait method that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option-diagnostics.rs:39:14
@@ -39,8 +33,6 @@ LL |         fn a_trait_method() {
 LL |             let x: Option<u32> = None;
 LL |             x?;
    |              ^ cannot use the `?` operator in a trait method that returns `()`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `()`
 
 error: aborting due to 4 previous errors
 

tests/ui/try-trait/try-on-option.stderr

@@ -6,9 +6,6 @@ LL | fn foo() -> Result<u32, ()> {
 LL |     let x: Option<u32> = None;
 LL |     x?;
    |      ^ use `.ok_or(...)?` to provide an error compatible with `Result<u32, ()>`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<u32, ()>`
-   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> $DIR/try-on-option.rs:11:6
@@ -18,8 +15,6 @@ LL | fn bar() -> u32 {
 LL |     let x: Option<u32> = None;
 LL |     x?;
    |      ^ cannot use the `?` operator in a function that returns `u32`
-   |
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `u32`
 
 error: aborting due to 2 previous errors
 

tests/ui/try-trait/try-operator-on-main.stderr

@@ -7,7 +7,6 @@ LL |     // error for a `Try` type on a non-`Try` fn
 LL |     std::fs::File::open("foo")?;
    |                               ^ cannot use the `?` operator in a function that returns `()`
    |
-   = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()`
 help: consider adding return type
    |
 LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> {
@@ -33,8 +32,6 @@ LL | fn main() {
 ...
 LL |     ()?;
    |       ^ cannot use the `?` operator in a function that returns `()`
-   |
-   = help: the trait `FromResidual<_>` is not implemented for `()`
 
 error[E0277]: the trait bound `(): Try` is not satisfied
   --> $DIR/try-operator-on-main.rs:14:25