From: Markus Westerlind <markus.westerlind@imperva.com>
Date: Mon, 13 Jan 2020 08:17:10 +0000 (+0100)
Subject: Explain fold_list
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=a1586f1d2b17d687444d3b94aedd7ce24ae074ed;p=rust.git

Explain fold_list
---

diff --git a/src/librustc/ty/structural_impls.rs b/src/librustc/ty/structural_impls.rs
index 783164d2806..eade5154c8a 100644
--- 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,