Rollup merge of #137956 - compiler-errors:rtn-rustdoc, r=fmease

Add RTN support to rustdoc

This adds support to rustdoc and rustdoc-json for rendering `(..)` RTN (return type notation) style generics.

---

Cleaning `rustc_middle::ty::Ty` is not correct still, though, and ends up rendering a function like:

```rust
pub fn foreign<T: Foreign<bar(..): Send>>()
where
    <T as Foreign>::bar(..): 'static,
    T::bar(..): Sync,
```

Into this:

```rust
pub fn foreign<T>()
where
    T: Foreign,
    impl Future<Output = ()>: Send + 'static + Sync,
```

This is because `clean_middle_ty` doesn't actually have sufficient context about whether the RPITIT is in its "defining scope" or not, so we don't know if the type was originally written like `-> impl Trait` or with RTN like `T::method(..)`.

Partially addresses #123996 (i.e., HIR side, not middle::ty one)

1 files changed, 1 insertions, 0 deletions

diff --git a/src/tools/jsondoclint/src/validator.rs b/src/tools/jsondoclint/src/validator.rs
index 791b231c27a..8c9e4c8bb3a 100644
--- a/src/tools/jsondoclint/src/validator.rs
+++ b/src/tools/jsondoclint/src/validator.rs
@@ -326,6 +326,7 @@ impl<'a> Validator<'a> {
                     self.check_type(o);
                 }
             }
+            GenericArgs::ReturnTypeNotation => {}
         }
     }