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diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs
index 435f2877fb3292bc9ac0cbd881204a9f61039162..0658836fb9cd36a8d58aac9c6da7573a801cfeed 100644 (file)
--- a/compiler/rustc_trait_selection/src/solve/project_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs
@@ -82,6 +82,7 @@ fn term_is_fully_unconstrained(&self, goal: Goal<'tcx, ProjectionPredicate<'tcx>
             }
         };
 
+        // Guard against `<T as Trait<?0>>::Assoc = ?0>`.
         struct ContainsTerm<'tcx> {
             term: ty::Term<'tcx>,
         }