Tweak invalid RTN errors

Make suggestions verbose.

When encountering `method(type)` bound, suggest `method(..)` instead of `method()`.

```
error: argument types not allowed with return type notation
  --> $DIR/bad-inputs-and-output.rs:9:23
   |
LL | fn foo<T: Trait<method(i32): Send>>() {}
   |                       ^^^^^
   |
help: remove the input types
   |
LL - fn foo<T: Trait<method(i32): Send>>() {}
LL + fn foo<T: Trait<method(..): Send>>() {}
   |
```

When encountering both return type and arg list that isn't `..`, suggest replacing both.

```
error: return type not allowed with return type notation
  --> $DIR/bad-inputs-and-output.rs:12:25
   |
LL | fn bar<T: Trait<method() -> (): Send>>() {}
   |                         ^^^^^^
   |
help: use the right argument notation and remove the return type
   |
LL - fn bar<T: Trait<method() -> (): Send>>() {}
LL + fn bar<T: Trait<method(..): Send>>() {}
   |
```

When encountering a return type, suggest removing it including the leading whitespace.

```
error: return type not allowed with return type notation
  --> $DIR/bad-inputs-and-output.rs:24:45
   |
LL | fn bay_path<T: Trait>() where T::method(..) -> (): Send {}
   |                                             ^^^^^
   |
help: remove the return type
   |
LL - fn bay_path<T: Trait>() where T::method(..) -> (): Send {}
LL + fn bay_path<T: Trait>() where T::method(..): Send {}
   |
```

3 files changed, 66 insertions, 12 deletions

diff --git a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
index f00aaec1a8c..90fd2c2b4f3 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
+++ b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.rs
@@ -21,6 +21,9 @@ fn foo_path<T: Trait>() where T::method(i32): Send {}
 fn bar_path<T: Trait>() where T::method() -> (): Send {}
 //~^ ERROR return type not allowed with return type notation
 
+fn bay_path<T: Trait>() where T::method(..) -> (): Send {}
+//~^ ERROR return type not allowed with return type notation
+
 fn baz_path<T: Trait>() where T::method(): Send {}
 //~^ ERROR return type notation arguments must be elided with `..`
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
index c6b9f3eff90..bd02b7d6534 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/bad-inputs-and-output.stderr
@@ -1,17 +1,29 @@
+error: return type not allowed with return type notation
+  --> $DIR/bad-inputs-and-output.rs:24:45
+   |
+LL | fn bay_path<T: Trait>() where T::method(..) -> (): Send {}
+   |                                             ^^^^^
+   |
+help: remove the return type
+   |
+LL - fn bay_path<T: Trait>() where T::method(..) -> (): Send {}
+LL + fn bay_path<T: Trait>() where T::method(..): Send {}
+   |
+
 error[E0575]: expected associated type, found associated function `Trait::method`
-  --> $DIR/bad-inputs-and-output.rs:27:36
+  --> $DIR/bad-inputs-and-output.rs:30:36
    |
 LL | fn foo_qualified<T: Trait>() where <T as Trait>::method(i32): Send {}
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^ not a associated type
 
 error[E0575]: expected associated type, found associated function `Trait::method`
-  --> $DIR/bad-inputs-and-output.rs:30:36
+  --> $DIR/bad-inputs-and-output.rs:33:36
    |
 LL | fn bar_qualified<T: Trait>() where <T as Trait>::method() -> (): Send {}
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not a associated type
 
 error[E0575]: expected associated type, found associated function `Trait::method`
-  --> $DIR/bad-inputs-and-output.rs:33:36
+  --> $DIR/bad-inputs-and-output.rs:36:36
    |
 LL | fn baz_qualified<T: Trait>() where <T as Trait>::method(): Send {}
    |                                    ^^^^^^^^^^^^^^^^^^^^^^ not a associated type
@@ -20,38 +32,72 @@ error: argument types not allowed with return type notation
   --> $DIR/bad-inputs-and-output.rs:9:23
    |
 LL | fn foo<T: Trait<method(i32): Send>>() {}
-   |                       ^^^^^ help: remove the input types: `()`
+   |                       ^^^^^
+   |
+help: remove the input types
+   |
+LL - fn foo<T: Trait<method(i32): Send>>() {}
+LL + fn foo<T: Trait<method(..): Send>>() {}
+   |
 
 error: return type not allowed with return type notation
   --> $DIR/bad-inputs-and-output.rs:12:25
    |
 LL | fn bar<T: Trait<method() -> (): Send>>() {}
-   |                         ^^^^^^ help: remove the return type
+   |                         ^^^^^^
+   |
+help: use the right argument notation and remove the return type
+   |
+LL - fn bar<T: Trait<method() -> (): Send>>() {}
+LL + fn bar<T: Trait<method(..): Send>>() {}
+   |
 
 error: return type notation arguments must be elided with `..`
   --> $DIR/bad-inputs-and-output.rs:15:23
    |
 LL | fn baz<T: Trait<method(): Send>>() {}
-   |                       ^^ help: add `..`: `(..)`
+   |                       ^^
+   |
+help: use the correct syntax by adding `..` to the arguments
+   |
+LL | fn baz<T: Trait<method(..): Send>>() {}
+   |                        ++
 
 error: argument types not allowed with return type notation
   --> $DIR/bad-inputs-and-output.rs:18:40
    |
 LL | fn foo_path<T: Trait>() where T::method(i32): Send {}
-   |                                        ^^^^^ help: remove the input types: `()`
+   |                                        ^^^^^
+   |
+help: remove the input types
+   |
+LL - fn foo_path<T: Trait>() where T::method(i32): Send {}
+LL + fn foo_path<T: Trait>() where T::method(..): Send {}
+   |
 
 error: return type not allowed with return type notation
   --> $DIR/bad-inputs-and-output.rs:21:42
    |
 LL | fn bar_path<T: Trait>() where T::method() -> (): Send {}
-   |                                          ^^^^^^ help: remove the return type
+   |                                          ^^^^^^
+   |
+help: use the right argument notation and remove the return type
+   |
+LL - fn bar_path<T: Trait>() where T::method() -> (): Send {}
+LL + fn bar_path<T: Trait>() where T::method(..): Send {}
+   |
 
 error: return type notation arguments must be elided with `..`
-  --> $DIR/bad-inputs-and-output.rs:24:40
+  --> $DIR/bad-inputs-and-output.rs:27:40
    |
 LL | fn baz_path<T: Trait>() where T::method(): Send {}
-   |                                        ^^ help: add `..`: `(..)`
+   |                                        ^^
+   |
+help: use the correct syntax by adding `..` to the arguments
+   |
+LL | fn baz_path<T: Trait>() where T::method(..): Send {}
+   |                                         ++
 
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors
 
 For more information about this error, try `rustc --explain E0575`.
diff --git a/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr b/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
index 83a5441e3c0..19a0e4b17d0 100644
--- a/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
+++ b/tests/ui/suggestions/let-binding-init-expr-as-ty.stderr
@@ -10,11 +10,16 @@ error: argument types not allowed with return type notation
   --> $DIR/let-binding-init-expr-as-ty.rs:2:26
    |
 LL |     let foo: i32::from_be(num);
-   |                          ^^^^^ help: remove the input types: `()`
+   |                          ^^^^^
    |
    = note: see issue #109417 <https://github.com/rust-lang/rust/issues/109417> for more information
    = help: add `#![feature(return_type_notation)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+help: remove the input types
+   |
+LL -     let foo: i32::from_be(num);
+LL +     let foo: i32::from_be(..);
+   |
 
 error: return type notation not allowed in this position yet
   --> $DIR/let-binding-init-expr-as-ty.rs:2:14