Add array_lt_test_cx.cpp

include/boost/array.hpp

@@ -337,8 +337,15 @@ namespace boost {
     }
 
     template<class T, std::size_t N>
-    BOOST_CXX14_CONSTEXPR bool operator< (const array<T,N>& x, const array<T,N>& y) {
-        return std::lexicographical_compare(x.begin(),x.end(),y.begin(),y.end());
+    BOOST_CXX14_CONSTEXPR bool operator< (const array<T,N>& x, const array<T,N>& y)
+    {
+        for( std::size_t i = 0; i < N; ++i )
+        {
+            if( x[ i ] < y[ i ] ) return true;
+            if( y[ i ] < x[ i ] ) return false;
+        }
+
+        return false;
     }
 
     template<class T, std::size_t N>

test/Jamfile.v2

@@ -59,6 +59,7 @@ compile array_access_test_cx.cpp ;
 # C++14 constexpr
 
 compile array_eq_test_cx.cpp ;
+compile array_lt_test_cx.cpp ;
 
 #
 

test/array_lt_test_cx.cpp

@@ -0,0 +1,74 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/array.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+#include <boost/config/workaround.hpp>
+#include <cstddef>
+
+#if defined(BOOST_NO_CXX14_CONSTEXPR)
+
+BOOST_PRAGMA_MESSAGE("Test skipped because BOOST_NO_CXX14_CONSTEXPR is defined")
+
+#else
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+template<class T, std::size_t N> void test1()
+{
+    constexpr boost::array<T, N> a1 = {};
+    constexpr boost::array<T, N> a2 = {};
+
+    STATIC_ASSERT( !( a1 < a2 ) );
+    STATIC_ASSERT( !( a1 > a2 ) );
+
+    STATIC_ASSERT( a1 <= a2 );
+    STATIC_ASSERT( a1 >= a2 );
+}
+
+template<class T> void test2()
+{
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 4 }};
+
+        STATIC_ASSERT( !( a1 < a2 ) );
+        STATIC_ASSERT( !( a1 > a2 ) );
+
+        STATIC_ASSERT( a1 <= a2 );
+        STATIC_ASSERT( a1 >= a2 );
+    }
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 5 }};
+
+        STATIC_ASSERT( a1 < a2 );
+        STATIC_ASSERT( !( a1 > a2 ) );
+
+        STATIC_ASSERT( a1 <= a2 );
+        STATIC_ASSERT( !( a1 >= a2 ) );
+    }
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 2 }};
+
+        STATIC_ASSERT( !( a1 < a2 ) );
+        STATIC_ASSERT( a1 > a2 );
+
+        STATIC_ASSERT( !( a1 <= a2 ) );
+        STATIC_ASSERT( a1 >= a2 );
+    }
+}
+
+int main()
+{
+    test1<int, 0>();
+    test1<int, 1>();
+    test1<int, 7>();
+
+    test2<int>();
+}
+
+#endif