From 29f5d8f00f5c0287e8991d5818bd87942e6f4563 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 17 Jul 2024 18:17:30 -0400
Subject: [PATCH] Don't elaborate associated types with Sized bounds in
 trait_object_ty in cfi

---
 .../cfi/typeid/itanium_cxx_abi/transform.rs   |  1 +
 tests/ui/sanitizer/cfi-sized-associated-ty.rs | 38 +++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 tests/ui/sanitizer/cfi-sized-associated-ty.rs

diff --git a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
index f0f2d1fefd2f3..7ed36e8598950 100644
--- a/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
+++ b/compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/transform.rs
@@ -230,6 +230,7 @@ fn trait_object_ty<'tcx>(tcx: TyCtxt<'tcx>, poly_trait_ref: ty::PolyTraitRef<'tc
             tcx.associated_items(super_poly_trait_ref.def_id())
                 .in_definition_order()
                 .filter(|item| item.kind == ty::AssocKind::Type)
+                .filter(|item| !tcx.generics_require_sized_self(item.def_id))
                 .map(move |assoc_ty| {
                     super_poly_trait_ref.map_bound(|super_trait_ref| {
                         let alias_ty =
diff --git a/tests/ui/sanitizer/cfi-sized-associated-ty.rs b/tests/ui/sanitizer/cfi-sized-associated-ty.rs
new file mode 100644
index 0000000000000..f5b4e22e9d99b
--- /dev/null
+++ b/tests/ui/sanitizer/cfi-sized-associated-ty.rs
@@ -0,0 +1,38 @@
+// Check that we only elaborate non-`Self: Sized` associated types when
+// erasing the receiver from trait ref.
+
+//@ revisions: cfi kcfi
+// FIXME(#122848) Remove only-linux once OSX CFI binaries work
+//@ only-linux
+//@ [cfi] needs-sanitizer-cfi
+//@ [kcfi] needs-sanitizer-kcfi
+//@ compile-flags: -C target-feature=-crt-static
+//@ [cfi] compile-flags: -C codegen-units=1 -C lto -C prefer-dynamic=off -C opt-level=0
+//@ [cfi] compile-flags: -Z sanitizer=cfi
+//@ [kcfi] compile-flags: -Z sanitizer=kcfi
+//@ [kcfi] compile-flags: -C panic=abort -C prefer-dynamic=off
+//@ run-pass
+
+trait Foo {
+    type Bar<'a>
+    where
+        Self: Sized;
+
+    fn test(&self);
+}
+
+impl Foo for () {
+    type Bar<'a> = ()
+    where
+        Self: Sized;
+
+    fn test(&self) {}
+}
+
+fn test(x: &dyn Foo) {
+    x.test();
+}
+
+fn main() {
+    test(&());
+}