Auto merge of #123792 - oli-obk:coroutine_closures, r=compiler-errors

Require explicitly marking closures as coroutines

instead of relying on patching up the closure to be a coroutine if it happens to contain a `yield` expression.

I only do this in the 2024 edition, as the `gen` keyword is only available there.

1 files changed, 7 insertions, 3 deletions

diff --git a/compiler/rustc_codegen_cranelift/example/std_example.rs b/compiler/rustc_codegen_cranelift/example/std_example.rs
index 0205de55622..90d4ab721da 100644
--- a/compiler/rustc_codegen_cranelift/example/std_example.rs
+++ b/compiler/rustc_codegen_cranelift/example/std_example.rs
@@ -1,6 +1,7 @@
 #![feature(
     core_intrinsics,
     coroutines,
+    stmt_expr_attributes,
     coroutine_trait,
     is_sorted,
     repr_simd,
@@ -123,9 +124,12 @@ fn main() {
         test_simd();
     }
 
-    Box::pin(move |mut _task_context| {
-        yield ();
-    })
+    Box::pin(
+        #[coroutine]
+        move |mut _task_context| {
+            yield ();
+        },
+    )
     .as_mut()
     .resume(0);