diff --git a/compiler/rustc_ty_utils/src/opaque_types.rs b/compiler/rustc_ty_utils/src/opaque_types.rs
index 5415662154daf..1b951ccb70ea3 100644
--- a/compiler/rustc_ty_utils/src/opaque_types.rs
+++ b/compiler/rustc_ty_utils/src/opaque_types.rs
@@ -33,8 +33,7 @@ enum CollectionMode {
     ImplTraitInAssocTypes,
     /// When collecting for an explicit `#[define_opaque]` attribute, find all TAITs
     Taits,
-    /// The default case, only collect RPITs and AsyncFn return types, as these are
-    /// always defined by the current item.
+    /// By default collect RPITs and async function return types defined by this item
     RpitAndAsyncFnOnly,
 }
 
@@ -323,6 +322,12 @@ fn opaque_types_defined_by<'tcx>(
     if tcx.is_typeck_child(item.to_def_id()) {
         return tcx.opaque_types_defined_by(tcx.local_parent(item));
     }
+
+    // delegation inherits its signature without defining its opaque types
+    if tcx.hir_opt_delegation_sig_id(item).is_some() {
+        return tcx.mk_local_def_ids(&[]);
+    }
+
     let kind = tcx.def_kind(item);
     trace!(?kind);
     let mut collector = OpaqueTypeCollector::new(tcx, item);
diff --git a/tests/ui/delegation/fn-header.next.stderr b/tests/ui/delegation/fn-header.next.stderr
deleted file mode 100644
index adca7d80a9b1d..0000000000000
--- a/tests/ui/delegation/fn-header.next.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error[E0282]: type annotations needed
-  --> $DIR/fn-header.rs:23:17
-   |
-LL | reuse to_reuse::async_fn;
-   |                 ^^^^^^^^ cannot infer type
-   |
-   = note: cannot infer type of hidden type of opaque
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/delegation/fn-header.rs b/tests/ui/delegation/fn-header.rs
index 8aae776e295ff..a036dec4872a9 100644
--- a/tests/ui/delegation/fn-header.rs
+++ b/tests/ui/delegation/fn-header.rs
@@ -1,8 +1,7 @@
 //@ revisions: old next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
-//@[next] known-bug: trait-system-refactor-initiative#304
-//@[old] check-pass
+//@ check-pass
 //@ edition:2018
 //@ aux-crate:fn_header_aux=fn-header-aux.rs
 //@ ignore-backends: gcc
diff --git a/tests/ui/delegation/impl-trait.next.stderr b/tests/ui/delegation/impl-trait.next.stderr
deleted file mode 100644
index 84e1e8ec4453a..0000000000000
--- a/tests/ui/delegation/impl-trait.next.stderr
+++ /dev/null
@@ -1,19 +0,0 @@
-error[E0282]: type annotations needed
-  --> $DIR/impl-trait.rs:13:17
-   |
-LL | reuse to_reuse::foo;
-   |                 ^^^ cannot infer type
-   |
-   = note: cannot infer type of hidden type of opaque
-
-error[E0282]: type annotations needed
-  --> $DIR/impl-trait.rs:23:21
-   |
-LL |     reuse to_reuse::foo;
-   |                     ^^^ cannot infer type
-   |
-   = note: cannot infer type of hidden type of opaque
-
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/delegation/impl-trait.rs b/tests/ui/delegation/impl-trait.rs
index 3b0d1a0383549..c6aec41dd3246 100644
--- a/tests/ui/delegation/impl-trait.rs
+++ b/tests/ui/delegation/impl-trait.rs
@@ -1,8 +1,7 @@
 //@ revisions: old next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
-//@[next] known-bug: trait-system-refactor-initiative#304
-//@[old] check-pass
+//@ check-pass
 
 #![feature(fn_delegation)]