Rollup merge of #105174 - chenyukang:yukang/fix-105028-unused, r=eholk

[rust.git] / compiler / rustc_trait_selection / src / traits / select / candidate_assembly.rs

diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index fe5135661b5f8f3996649ee9519849d747ad08e3..e4b70f0d2ffa7afbfc54dbf7fdaa252400ef1226 100644 (file)
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -203,7 +203,9 @@ fn assemble_generator_candidates(
         // type/region parameters.
         let self_ty = obligation.self_ty().skip_binder();
         match self_ty.kind() {
-            ty::Generator(..) => {
+            // async constructs get lowered to a special kind of generator that
+            // should *not* `impl Generator`.
+            ty::Generator(did, ..) if !self.tcx().generator_is_async(*did) => {
                 debug!(?self_ty, ?obligation, "assemble_generator_candidates",);
 
                 candidates.vec.push(GeneratorCandidate);
@@ -223,6 +225,8 @@ fn assemble_future_candidates(
     ) {
         let self_ty = obligation.self_ty().skip_binder();
         if let ty::Generator(did, ..) = self_ty.kind() {
+            // async constructs get lowered to a special kind of generator that
+            // should directly `impl Future`.
             if self.tcx().generator_is_async(*did) {
                 debug!(?self_ty, ?obligation, "assemble_future_candidates",);