Fix ICE when using attributes on delegation items

Delegation items are skipped by  via
, so they were never added to .
This caused a debug assertion failure when an attribute like
 generated a delayed lint on the item.

Fixes #155127

Author: RaghavenderSingh

compiler/rustc_middle/src/hir/map.rs

@@ -1335,7 +1335,7 @@ impl<'tcx> ItemCollector<'tcx> {
             let delayed_kinds =
                 krate.delayed_ids.iter().copied().map(|id| (id, krate.owners[id].expect_delayed()));
 
-            // FIXME(fn_delegation): need to add delayed lints, eiis
+            // FIXME(fn_delegation): need to add eiis
             for (def_id, kind) in delayed_kinds {
                 let owner_id = OwnerId { def_id };
 
@@ -1350,6 +1350,9 @@ impl<'tcx> ItemCollector<'tcx> {
                 };
 
                 collector.body_owners.push(def_id);
+                // Delegation items are skipped by the HIR walk (see `visit_if_delayed`),
+                // so we have to account for their delayed lints manually.
+                collector.delayed_lint_items.push(owner_id);
             }
         }
 

tests/ui/delegation/ice-issue-155127.rs

@@ -0,0 +1,17 @@
+// https://github.com/rust-lang/rust/issues/155127
+
+#![feature(fn_delegation)]
+#![allow(incomplete_features)]
+
+struct S;
+
+fn foo() {}
+
+impl S {
+    #[deprecated]
+    //~^ ERROR `#[deprecated]` attribute cannot be used on delegations
+    //~| WARN this was previously accepted by the compiler but is being phased out
+    reuse foo;
+}
+
+fn main() {}

tests/ui/delegation/ice-issue-155127.stderr

@@ -0,0 +1,12 @@
+error: `#[deprecated]` attribute cannot be used on delegations
+  --> $DIR/ice-issue-155127.rs:11:5
+   |
+LL |     #[deprecated]
+   |     ^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[deprecated]` can be applied to associated consts, associated types, constants, crates, data types, enum variants, foreign statics, functions, inherent impl blocks, macro defs, modules, statics, struct fields, traits, type aliases, and use statements
+   = note: `#[deny(useless_deprecated)]` on by default
+
+error: aborting due to 1 previous error
+