Explain fold_list

diff --git a/src/librustc/ty/structural_impls.rs b/src/librustc/ty/structural_impls.rs
index 783164d2806c1e77d9c001dc7559e2313d91a8b3..eade5154c8ad0cabe6632efdcf0febd6a602bf38 100644 (file)
--- a/src/librustc/ty/structural_impls.rs
+++ b/src/librustc/ty/structural_impls.rs
@@ -1061,6 +1061,11 @@ fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
     }
 }
 
+// Does the equivalent of
+// ```
+// let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
+// folder.tcx().intern_*(&v)
+// ```
 fn fold_list<'tcx, F, T>(
     list: &'tcx ty::List<T>,
     folder: &mut F,