From 040791a9c59d2f604060efb75c81f685ceb5f9db Mon Sep 17 00:00:00 2001
From: Bryanskiy <ivakin.kir@gmail.com>
Date: Mon, 10 Jun 2024 18:02:53 +0300
Subject: [PATCH] Delegation: fix ICE on late diagnostics

---
 .../rustc_resolve/src/late/diagnostics.rs     |  7 +++++--
 tests/crashes/124342.rs                       |  6 ------
 tests/ui/delegation/ice-issue-124342.rs       | 12 +++++++++++
 tests/ui/delegation/ice-issue-124342.stderr   | 20 +++++++++++++++++++
 4 files changed, 37 insertions(+), 8 deletions(-)
 delete mode 100644 tests/crashes/124342.rs
 create mode 100644 tests/ui/delegation/ice-issue-124342.rs
 create mode 100644 tests/ui/delegation/ice-issue-124342.stderr

diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index ec24eac4a9d09..9eeb0da7ed2fd 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -2041,8 +2041,11 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
                         ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn { called },
                         ast::AssocItemKind::Type(..) => AssocSuggestion::AssocType,
                         ast::AssocItemKind::Delegation(..)
-                            if self.r.delegation_fn_sigs[&self.r.local_def_id(assoc_item.id)]
-                                .has_self =>
+                            if self
+                                .r
+                                .delegation_fn_sigs
+                                .get(&self.r.local_def_id(assoc_item.id))
+                                .map_or(false, |sig| sig.has_self) =>
                         {
                             AssocSuggestion::MethodWithSelf { called }
                         }
diff --git a/tests/crashes/124342.rs b/tests/crashes/124342.rs
deleted file mode 100644
index ae51b3db96f5d..0000000000000
--- a/tests/crashes/124342.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-//@ known-bug: #124342
-trait Trait2 : Trait {
-   reuse <() as Trait>::async {
-        (async || {}).await;
-    };
-}
diff --git a/tests/ui/delegation/ice-issue-124342.rs b/tests/ui/delegation/ice-issue-124342.rs
new file mode 100644
index 0000000000000..ad62f6bd54af9
--- /dev/null
+++ b/tests/ui/delegation/ice-issue-124342.rs
@@ -0,0 +1,12 @@
+#![feature(fn_delegation)]
+#![allow(incomplete_features)]
+
+mod to_reuse {}
+
+trait Trait {
+    reuse to_reuse::foo { foo }
+    //~^ ERROR cannot find function `foo` in module `to_reuse`
+    //~| ERROR cannot find value `foo` in this scope
+}
+
+fn main() {}
diff --git a/tests/ui/delegation/ice-issue-124342.stderr b/tests/ui/delegation/ice-issue-124342.stderr
new file mode 100644
index 0000000000000..f9a3684d64932
--- /dev/null
+++ b/tests/ui/delegation/ice-issue-124342.stderr
@@ -0,0 +1,20 @@
+error[E0425]: cannot find function `foo` in module `to_reuse`
+  --> $DIR/ice-issue-124342.rs:7:21
+   |
+LL |     reuse to_reuse::foo { foo }
+   |                     ^^^ not found in `to_reuse`
+
+error[E0425]: cannot find value `foo` in this scope
+  --> $DIR/ice-issue-124342.rs:7:27
+   |
+LL |     reuse to_reuse::foo { foo }
+   |                           ^^^
+   |
+help: you might have meant to refer to the associated function
+   |
+LL |     reuse to_reuse::foo { Self::foo }
+   |                           ++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0425`.