fix C4127: Conditional Expression is Constant

modules/c++/sys/unittests/test_NaN_testing.cpp

@@ -63,6 +63,12 @@ TEST_CASE(testIsNaN)
 
 TEST_CASE(test_ssize)
 {
+#if __cplusplus >= 201703L
+#define CONSTEXPR constexpr
+#else
+#define CONSTEXPR
+#endif
+
     // https://en.cppreference.com/w/cpp/iterator/size
 
     // Works with containers
@@ -72,13 +78,13 @@ TEST_CASE(test_ssize)
     // And works with built-in arrays too
     int a[]{-5, 10, 15};
     // Returns the number of elements (not bytes) as opposed to sizeof
-    TEST_ASSERT_EQ(std::size(a), 3);
+    TEST_ASSERT_EQ(CONSTEXPR std::size(a), 3);
     static_assert(sizeof(a) == 12, "sizeof(a)");
 
     // Provides a safe way (compared to sizeof) of getting string buffer size
     const char str[] = "12345";
     // These are fine and give the correct result
-    TEST_ASSERT_EQ(std::size(str), 6);
+    TEST_ASSERT_EQ(CONSTEXPR std::size(str), 6);
     static_assert(sizeof(str) == 6, "sizeof(str)");
 
     // But use of sizeof here is a common source of bugs
@@ -89,6 +95,8 @@ TEST_CASE(test_ssize)
     auto i = std::ssize(v);
     for (--i; i != -1; --i) { }
     TEST_ASSERT_EQ(i, -1);
+
+#undef CONSTEXPR
 }
 
 TEST_MAIN(