bless tests, fix pesky type error

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -831,14 +831,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     // of the `impl Sized`. Insert that here, so we don't ICE later.
     for assoc_item in tcx.associated_types_for_impl_traits_in_associated_fn(trait_m.def_id) {
         if !remapped_types.contains_key(assoc_item) {
-            remapped_types.insert(
-                *assoc_item,
-                ty::EarlyBinder::bind(Ty::new_error_with_message(
-                    tcx,
-                    return_span,
-                    "missing synthetic item for RPITIT",
-                )),
-            );
+            return Err(tcx.sess.delay_span_bug(return_span, "missing synthetic item for RPITIT"));
         }
     }
 

tests/rustdoc/inline_cross/auxiliary/ret-pos-impl-trait-in-trait.rs

@@ -1,4 +1,4 @@
-#![feature(return_position_impl_trait_in_trait)]
+#![feature(return_position_impl_trait_in_trait, refine)]
 
 pub trait Trait {
     fn create() -> impl Iterator<Item = u64> {
@@ -15,6 +15,7 @@ impl Trait for Basic {
 }
 
 impl Trait for Intermediate {
+    #[refine]
     fn create() -> std::ops::Range<u64> { // concrete return type
         0..1
     }

tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.rs

@@ -17,6 +17,7 @@ impl<'a, I: 'a + Iterable> Iterable for &'a I {
     //~^ ERROR impl has stricter requirements than trait
 
     fn iter(&self) -> impl 'a + Iterator<Item = I::Item<'a>> {
+        //~^ ERROR impl method signature does not match trait method signature
         (*self).iter()
     }
 }

tests/ui/impl-trait/in-trait/bad-item-bound-within-rpitit.stderr

@@ -12,6 +12,20 @@ help: copy the `where` clause predicates from the trait
 LL |     where Self: 'b;
    |     ~~~~~~~~~~~~~~
 
-error: aborting due to previous error
+error: impl method signature does not match trait method signature
+  --> $DIR/bad-item-bound-within-rpitit.rs:19:23
+   |
+LL |     fn iter(&self) -> impl '_ + Iterator<Item = Self::Item<'_>>;
+   |                       ----------------------------------------- return type from trait method defined here
+...
+LL |     fn iter(&self) -> impl 'a + Iterator<Item = I::Item<'a>> {
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: replace the return type so that it matches the trait
+   |
+LL |     fn iter(&self) -> impl Iterator<Item = <&'a I as Iterable>::Item<'_>> + '_ {
+   |                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0276`.