Check if type has coroutines before visiting

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -10,7 +10,8 @@ use rustc_infer::traits::{
     FromSolverError, PredicateObligation, PredicateObligations, TraitEngine,
 };
 use rustc_middle::ty::{
-    self, DelayedSet, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor, TypingMode,
+    self, DelayedSet, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
+    TypingMode,
 };
 use rustc_next_trait_solver::delegate::SolverDelegate as _;
 use rustc_next_trait_solver::solve::{
@@ -332,10 +333,12 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for StalledOnCoroutines<'tcx> {
         if let ty::CoroutineWitness(def_id, _) = *ty.kind()
             && def_id.as_local().is_some_and(|def_id| self.stalled_generators.contains(&def_id))
         {
-            return ControlFlow::Break(());
+            ControlFlow::Break(())
+        } else if ty.has_coroutines() {
+            ty.super_visit_with(self)
+        } else {
+            ControlFlow::Continue(())
         }
-
-        ty.super_visit_with(self)
     }
 }
 

compiler/rustc_type_ir/src/flags.rs

@@ -130,6 +130,12 @@ bitflags::bitflags! {
 
         /// Does this have any binders with bound vars (e.g. that need to be anonymized)?
         const HAS_BINDER_VARS             = 1 << 23;
+
+        /// Does this type have any coroutine witnesses in it?
+        // FIXME: This should probably be changed to track whether the type has any
+        // *coroutines* in it, though this will happen if we remove coroutine witnesses
+        // altogether.
+        const HAS_TY_CORO                 = 1 << 24;
     }
 }
 
@@ -240,10 +246,12 @@ impl<I: Interner> FlagComputation<I> {
                 self.add_flags(TypeFlags::HAS_TY_PARAM);
             }
 
-            ty::Closure(_, args)
+            ty::Closure(_, args) | ty::Coroutine(_, args) | ty::CoroutineClosure(_, args) => {
-            | ty::Coroutine(_, args)
+                self.add_args(args.as_slice());
-            | ty::CoroutineClosure(_, args)
+            }
-            | ty::CoroutineWitness(_, args) => {
+
+            ty::CoroutineWitness(_, args) => {
+                self.add_flags(TypeFlags::HAS_TY_CORO);
                 self.add_args(args.as_slice());
             }
 

compiler/rustc_type_ir/src/visit.rs

@@ -269,6 +269,10 @@ pub trait TypeVisitableExt<I: Interner>: TypeVisitable<I> {
         self.has_type_flags(TypeFlags::HAS_TY_OPAQUE)
     }
 
+    fn has_coroutines(&self) -> bool {
+        self.has_type_flags(TypeFlags::HAS_TY_CORO)
+    }
+
     fn references_error(&self) -> bool {
         self.has_type_flags(TypeFlags::HAS_ERROR)
     }