From 4620e74fbb00ed8f74e33d8c047379bdbc4ae4a6 Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Mon, 25 Sep 2023 17:40:37 +0000
Subject: [PATCH 1/2] Only prevent field projections into opaque types, not
 types containing opaque types

(cherry picked from commit 17b313fb5734df8186071d4e30e46673098bb6a9)
---
 .../src/mem_categorization.rs                 |  2 +-
 .../opaque-cast-field-access-in-future.rs     | 27 +++++++++++++++++++
 .../opaque-cast-field-access-in-future.stderr |  9 +++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/impl-trait/opaque-cast-field-access-in-future.rs
 create mode 100644 tests/ui/impl-trait/opaque-cast-field-access-in-future.stderr

diff --git a/compiler/rustc_hir_typeck/src/mem_categorization.rs b/compiler/rustc_hir_typeck/src/mem_categorization.rs
index 7fb1dc2347e05..9574da0212f58 100644
--- a/compiler/rustc_hir_typeck/src/mem_categorization.rs
+++ b/compiler/rustc_hir_typeck/src/mem_categorization.rs
@@ -464,7 +464,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
         // Opaque types can't have field projections, but we can instead convert
         // the current place in-place (heh) to the hidden type, and then apply all
         // follow up projections on that.
-        if node_ty != place_ty && place_ty.has_opaque_types() {
+        if node_ty != place_ty && matches!(place_ty.kind(), ty::Alias(ty::Opaque, ..)) {
             projections.push(Projection { kind: ProjectionKind::OpaqueCast, ty: node_ty });
         }
         projections.push(Projection { kind, ty });
diff --git a/tests/ui/impl-trait/opaque-cast-field-access-in-future.rs b/tests/ui/impl-trait/opaque-cast-field-access-in-future.rs
new file mode 100644
index 0000000000000..3e3bc09a62aa8
--- /dev/null
+++ b/tests/ui/impl-trait/opaque-cast-field-access-in-future.rs
@@ -0,0 +1,27 @@
+// edition: 2021
+
+use std::future::Future;
+
+async fn bop() {
+    fold(run(), |mut foo| async move {
+        &mut foo.bar;
+    })
+}
+
+fn fold<Fut, F, U>(_: Foo<U>, f: F)
+where
+    F: FnMut(Foo<U>) -> Fut,
+{
+    loop {}
+}
+
+struct Foo<F> {
+    bar: Vec<F>,
+}
+
+fn run() -> Foo<impl Future<Output = ()>> {
+    //~^ ERROR type annotations needed
+    loop {}
+}
+
+fn main() {}
diff --git a/tests/ui/impl-trait/opaque-cast-field-access-in-future.stderr b/tests/ui/impl-trait/opaque-cast-field-access-in-future.stderr
new file mode 100644
index 0000000000000..ee4343b110f26
--- /dev/null
+++ b/tests/ui/impl-trait/opaque-cast-field-access-in-future.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/opaque-cast-field-access-in-future.rs:22:17
+   |
+LL | fn run() -> Foo<impl Future<Output = ()>> {
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.

From a544df15297afc959a384a923f9581d0c53ac5a4 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov@redhat.com>
Date: Thu, 28 Sep 2023 13:41:02 +0200
Subject: [PATCH 2/2] Update LLVM submodule

(cherry picked from commit b325e9c60df758f1f1538c93e44b120a8fbf6d63)
---
 src/llvm-project | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/llvm-project b/src/llvm-project
index 42263494d29fe..d404cba4e39df 160000
--- a/src/llvm-project
+++ b/src/llvm-project
@@ -1 +1 @@
-Subproject commit 42263494d29febc26d3c1ebdaa7b63677573ec47
+Subproject commit d404cba4e39df595710869988ded7cbe1104b52f