From 7375bd058b48714d689d8404f7fc76b094412886 Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@nuwen.net>
Date: Fri, 12 May 2023 06:25:54 -0700
Subject: [PATCH] Fix IndexTransformIter. (#9155)

---
 src/common/transform_iterator.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/common/transform_iterator.h b/src/common/transform_iterator.h
index 83fffe05a..2efb0b725 100644
--- a/src/common/transform_iterator.h
+++ b/src/common/transform_iterator.h
@@ -26,9 +26,9 @@ class IndexTransformIter {
 
  public:
   using iterator_category = std::random_access_iterator_tag;  // NOLINT
-  using value_type = std::result_of_t<Fn(std::size_t)>;       // NOLINT
+  using reference = std::result_of_t<Fn(std::size_t)>;        // NOLINT
+  using value_type = std::remove_cv_t<std::remove_reference_t<reference>>; // NOLINT
   using difference_type = detail::ptrdiff_t;                  // NOLINT
-  using reference = std::add_lvalue_reference_t<value_type>;  // NOLINT
   using pointer = std::add_pointer_t<value_type>;             // NOLINT
 
  public:
@@ -43,8 +43,8 @@ class IndexTransformIter {
     return *this;
   }
 
-  value_type operator*() const { return fn_(iter_); }
-  value_type operator[](std::size_t i) const {
+  reference operator*() const { return fn_(iter_); }
+  reference operator[](std::size_t i) const {
     auto iter = *this + i;
     return *iter;
   }