From 992348b4bb2d0de2bdc5fa3d35ee83625caff69a Mon Sep 17 00:00:00 2001
From: Roland Reichwein <Roland.Reichwein@bmw.de>
Date: Thu, 19 Feb 2026 14:18:12 +0100
Subject: [PATCH] Add constexpr to array comparison operators (#1303)

* Remove AppVeyor build status badge

Removed AppVeyor build status badge from README.

* Update README.md

* Update CONTRIBUTING.md

Updated the instructions for contributing.

* Fix for issue 1276 "Data corruption in the etl::bip_buffer_spsc_atomic" (#1277)

* Reproduce data corruption bug in the `etl::bip_buffer_spsc_atomic`.

* Fix data corruption bug in the `etl::bip_buffer_spsc_atomic`.

* Add constexpr to array comparison operators

---------

Co-authored-by: John Wellbelove <jwellbelove@users.noreply.github.com>
Co-authored-by: Sergei <sergej.shirokov@gmail.com>
---
 include/etl/array.h |  4 ++--
 test/test_array.cpp | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/etl/array.h b/include/etl/array.h
index efb2ce04..f1624209 100644
--- a/include/etl/array.h
+++ b/include/etl/array.h
@@ -1136,7 +1136,7 @@ namespace etl
   ///\return <b>true</b> if the arrays are equal, otherwise <b>false</b>
   //*************************************************************************
   template <typename T, size_t SIZE>
-  bool operator ==(const etl::array<T, SIZE>& lhs, const etl::array<T, SIZE>& rhs)
+  ETL_CONSTEXPR14 bool operator ==(const etl::array<T, SIZE>& lhs, const etl::array<T, SIZE>& rhs)
   {
     return etl::equal(lhs.cbegin(), lhs.cend(), rhs.cbegin());
   }
@@ -1148,7 +1148,7 @@ namespace etl
   ///\return <b>true</b> if the arrays are not equal, otherwise <b>false</b>
   //*************************************************************************
   template <typename T, size_t SIZE>
-  bool operator !=(const etl::array<T, SIZE>& lhs, const etl::array<T, SIZE>& rhs)
+  ETL_CONSTEXPR14 bool operator !=(const etl::array<T, SIZE>& lhs, const etl::array<T, SIZE>& rhs)
   {
     return !(lhs == rhs);
   }
diff --git a/test/test_array.cpp b/test/test_array.cpp
index 9edd0719..27eaf674 100644
--- a/test/test_array.cpp
+++ b/test/test_array.cpp
@@ -631,6 +631,16 @@ namespace
       CHECK(data1 == data2);
     }
 
+    //*************************************************************************
+    TEST(test_equal_constexpr)
+    {
+      ETL_CONSTEXPR14 Data data1 = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+      ETL_CONSTEXPR14 Data data2 = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+
+      ETL_CONSTEXPR14 bool result = (data1 == data2);
+      CHECK(result);
+    }
+
     //*************************************************************************
     TEST(test_not_equal)
     {
@@ -640,6 +650,16 @@ namespace
       CHECK(data1 != data2);
     }
 
+    //*************************************************************************
+    TEST(test_not_equal_constexpr)
+    {
+      ETL_CONSTEXPR14 Data data1 = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+      ETL_CONSTEXPR14 Data data2 = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
+
+      ETL_CONSTEXPR14 bool result = (data1 != data2);
+      CHECK(result);
+    }
+
     //*************************************************************************
     TEST(test_less_than)
     {