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compiler/rustc_trait_selection/src/traits/effects.rs

@@ -368,7 +368,11 @@ fn evaluate_host_effect_for_copy_clone_goal<'tcx>(
 
         // only when `coroutine_clone` is enabled and the coroutine is movable
         // impl Copy/Clone for Coroutine where T: Copy/Clone forall T in (upvars, witnesses)
-        ty::Coroutine(def_id, args) => match tcx.coroutine_movability(def_id) {
+        ty::Coroutine(def_id, args) => {
+            if selcx.should_stall_coroutine(def_id) {
+                return Err(EvaluationFailure::Ambiguous);
+            }
+            match tcx.coroutine_movability(def_id) {
                 ty::Movability::Static => Err(EvaluationFailure::NoSolution),
                 ty::Movability::Movable => {
                     if tcx.features().coroutine_clone() {
@@ -380,7 +384,8 @@ fn evaluate_host_effect_for_copy_clone_goal<'tcx>(
                         Err(EvaluationFailure::NoSolution)
                     }
                 }
-        },
+            }
+        }
 
         ty::UnsafeBinder(_) => Err(EvaluationFailure::NoSolution),
 

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -2877,7 +2877,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         obligations
     }
 
-    fn should_stall_coroutine(&self, def_id: DefId) -> bool {
+    pub(super) fn should_stall_coroutine(&self, def_id: DefId) -> bool {
         match self.infcx.typing_mode() {
             TypingMode::Analysis { defining_opaque_types_and_generators: stalled_generators } => {
                 def_id.as_local().is_some_and(|def_id| stalled_generators.contains(&def_id))

compiler/rustc_type_ir/src/predicate.rs

@@ -121,7 +121,7 @@ impl<I: Interner> ty::Binder<I, TraitRef<I>> {
     }
 
     pub fn to_host_effect_clause(self, cx: I, constness: BoundConstness) -> I::Clause {
-        self.map_bound(|trait_ref: TraitRef<I>| {
+        self.map_bound(|trait_ref| {
             ty::ClauseKind::HostEffect(HostEffectPredicate { trait_ref, constness })
         })
         .upcast(cx)