From 252ac152864528ef0a6f0a54458e1ecf07a7ddfc Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Wed, 10 Jan 2024 10:25:42 +0000
Subject: [PATCH] Bubble up error type

---
 compiler/rustc_hir_typeck/src/closure.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_hir_typeck/src/closure.rs b/compiler/rustc_hir_typeck/src/closure.rs
index 7edb5912dd53..b6b332993151 100644
--- a/compiler/rustc_hir_typeck/src/closure.rs
+++ b/compiler/rustc_hir_typeck/src/closure.rs
@@ -802,7 +802,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .explicit_item_bounds(def_id)
                 .iter_instantiated_copied(self.tcx, args)
                 .find_map(|(p, s)| get_future_output(p.as_predicate(), s))?,
-            ty::Error(_) => return None,
+            ty::Error(_) => return Some(ret_ty),
             _ => span_bug!(
                 closure_span,
                 "async fn coroutine return type not an inference variable: {ret_ty}"