Account for impl Trait in "add bound" suggestion message

Author: estebank

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -531,6 +531,12 @@ pub fn suggest_constraining_type_params<'a>(
             SuggestChangingConstraintsMessage::RestrictBoundFurther => {
                 format!("consider further restricting this bound with {post}")
             }
+            SuggestChangingConstraintsMessage::RestrictTypeFurther { ty }
+            | SuggestChangingConstraintsMessage::RestrictType { ty }
+                if ty.starts_with("impl ") =>
+            {
+                format!("consider restricting opaque type `{ty}` with {post}")
+            }
             SuggestChangingConstraintsMessage::RestrictType { ty } => {
                 format!("consider restricting type parameter `{ty}` with {post}")
             }

tests/ui/suggestions/bound-suggestions.stderr

@@ -5,7 +5,7 @@ LL |     println!("{:?}", t);
    |                      ^ `impl Sized` cannot be formatted using `{:?}` because it doesn't implement `Debug`
    |
    = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
-help: consider further restricting type parameter `impl Sized` with trait `Debug`
+help: consider restricting opaque type `impl Sized` with trait `Debug`
    |
 LL | fn test_impl(t: impl Sized + std::fmt::Debug) {
    |                            +++++++++++++++++

tests/ui/suggestions/clone-bounds-121524.rs

@@ -6,7 +6,7 @@ trait DoesAThing {}
 impl DoesAThing for ThingThatDoesAThing {}
 
 fn clones_impl_ref_inline(thing: &impl DoesAThing) {
-    //~^ HELP consider further restricting type parameter `impl DoesAThing` with trait `Clone`
+    //~^ HELP consider restricting opaque type `impl DoesAThing` with trait `Clone`
     drops_impl_owned(thing.clone()); //~ ERROR E0277
     //~^ NOTE copies the reference
     //~| NOTE the trait `DoesAThing` is not implemented for `&impl DoesAThing`

tests/ui/suggestions/clone-bounds-121524.stderr

@@ -9,7 +9,7 @@ note: this `clone()` copies the reference, which does not do anything, because `
    |
 LL |     drops_impl_owned(thing.clone());
    |                            ^^^^^
-help: consider further restricting type parameter `impl DoesAThing` with trait `Clone`
+help: consider restricting opaque type `impl DoesAThing` with trait `Clone`
    |
 LL | fn clones_impl_ref_inline(thing: &impl DoesAThing + Clone) {
    |                                                   +++++++

tests/ui/suggestions/restrict-type-argument.stderr

@@ -11,7 +11,7 @@ note: required by a bound in `is_send`
    |
 LL | fn is_send<T: Send>(val: T) {}
    |               ^^^^ required by this bound in `is_send`
-help: consider further restricting type parameter `impl Sync` with trait `Send`
+help: consider restricting opaque type `impl Sync` with trait `Send`
    |
 LL | fn use_impl_sync(val: impl Sync + std::marker::Send) {
    |                                 +++++++++++++++++++