From b24e485aeeefb80d64398ed93284ee2f72bbe993 Mon Sep 17 00:00:00 2001
From: "Ryan M. Richard" <rrichard@ameslab.gov>
Date: Mon, 17 Nov 2025 21:52:35 -0600
Subject: [PATCH 1/2] adds cxx20 support

---
 CMakeLists.txt                                          | 1 +
 tests/unit_tests/type_traits/type_traits_extensions.cpp | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9f69ccb6..bb3c45d8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,7 @@ include(cmake/get_nwx_cmake.cmake)
 include(get_version_from_git)
 get_version_from_git(utilities_version "${CMAKE_CURRENT_LIST_DIR}")
 project(utilities VERSION "${utilities_version}" LANGUAGES CXX)
+set(CMAKE_CXX_STANDARD 20)
 
 include(nwx_versions)
 include(get_cmaize)
diff --git a/tests/unit_tests/type_traits/type_traits_extensions.cpp b/tests/unit_tests/type_traits/type_traits_extensions.cpp
index 48a9cf23..aa27ae0d 100644
--- a/tests/unit_tests/type_traits/type_traits_extensions.cpp
+++ b/tests/unit_tests/type_traits/type_traits_extensions.cpp
@@ -23,7 +23,7 @@ using namespace utilities;
 struct Struct1 {
     void begin();
     void swap(Struct1&);
-    bool operator!=(const Struct1&);
+    bool operator!=(const Struct1&) const;
     int operator*();
     int operator++(int);
     int operator[](int);
@@ -34,7 +34,7 @@ struct Struct1 {
 };
 struct Struct2 {
     using value_type = int;
-    bool operator==(const Struct2&);
+    bool operator==(const Struct2&) const;
     int operator++();
     Struct2* operator->();
     int operator--();

From 21bc68e1224538553eb0bf3f53c98c4e5537d2a1 Mon Sep 17 00:00:00 2001
From: "Ryan M. Richard" <rrichard@ameslab.gov>
Date: Mon, 17 Nov 2025 22:13:47 -0600
Subject: [PATCH 2/2] fix input iterator

---
 include/utilities/iterators/input_iterator_base.hpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/utilities/iterators/input_iterator_base.hpp b/include/utilities/iterators/input_iterator_base.hpp
index 16fa0e6b..4fab4e60 100644
--- a/include/utilities/iterators/input_iterator_base.hpp
+++ b/include/utilities/iterators/input_iterator_base.hpp
@@ -153,7 +153,7 @@ class InputIteratorBase {
      *  @return true if the two iterators are equal and false otherwise.
      *  @throws None. No throw guarantee
      */
-    bool operator==(const ParentType& rhs) const noexcept;
+    bool operator==(const InputIteratorBase& rhs) const noexcept;
 
     /** @brief Determines if two iterators point to different elements.
      *
@@ -166,7 +166,7 @@ class InputIteratorBase {
      *  @return false if the two iterators are equal and true otherwise.
      *  @throws None. No throw guarantee
      */
-    bool operator!=(const ParentType& rhs) const noexcept;
+    bool operator!=(const InputIteratorBase& rhs) const noexcept;
 
 protected:
     /// Downcasts this to a read-/write-able instance of the derived class
@@ -187,13 +187,13 @@ ParentType InputIteratorBase<ParentType>::operator++(int) {
 
 template<typename ParentType>
 bool InputIteratorBase<ParentType>::operator==(
-  const ParentType& rhs) const noexcept {
-    return downcast_().are_equal(rhs);
+  const InputIteratorBase& rhs) const noexcept {
+    return downcast_().are_equal(rhs.downcast_());
 }
 
 template<typename ParentType>
 bool InputIteratorBase<ParentType>::operator!=(
-  const ParentType& rhs) const noexcept {
+  const InputIteratorBase& rhs) const noexcept {
     return !((*this) == rhs);
 }