add compare

Author: AnjuDel

stl/inc/xstring

@@ -17,6 +17,10 @@
 #include <xpolymorphic_allocator.h>
 #endif // _HAS_CXX17
 
+#if _HAS_CXX20
+#include <compare>
+#endif // _HAS_CXX20
+
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, _STL_WARNING_LEVEL)
 #pragma warning(disable : _STL_DISABLED_WARNINGS)
@@ -39,7 +43,7 @@ struct _Char_traits { // properties of a string or stream element
     using pos_type            = streampos;
     using off_type            = streamoff;
     using state_type          = _Mbstatet;
-    using comparison_category = strong_ordering;
+    using comparison_category = _Comparison_category_strong;
 
     // For copy/move, we can uniformly call memcpy/memmove (or their builtin versions) for all element types.
 
@@ -218,7 +222,7 @@ public:
     using pos_type            = streampos;
     using off_type            = streamoff;
     using state_type          = mbstate_t;
-    using comparison_category = strong_ordering;
+    using comparison_category = _Comparison_category_strong;
 
     using _Primary_char_traits::_Copy_s;
     using _Primary_char_traits::copy;
@@ -357,7 +361,7 @@ public:
     using pos_type            = streampos;
     using off_type            = streamoff;
     using state_type          = mbstate_t;
-    using comparison_category = strong_ordering;
+    using comparison_category = _Comparison_category_strong;
 
     using _Primary_char_traits::_Copy_s;
     using _Primary_char_traits::copy;