Refactor <limits> usage

stl/inc/utility

@@ -849,17 +849,6 @@ _NODISCARD constexpr _Ty _Min_limit() noexcept { // same as (numeric_limits<_Ty>
  }
 }
 
-template <class _Ty>
-_NODISCARD constexpr _Ty _Max_limit() noexcept { // same as (numeric_limits<_Ty>::max)(), less throughput cost
- _STL_INTERNAL_STATIC_ASSERT(is_integral_v<_Ty>); // doesn't attempt to handle all types
- if constexpr (is_signed_v<_Ty>) {
- constexpr auto _Unsigned_max = static_cast<make_unsigned_t<_Ty>>(-1);
- return static_cast<_Ty>(_Unsigned_max >> 1);
- } else {
- return static_cast<_Ty>(-1);
- }
-}
-
 template <class _Rx, class _Ty>
 _NODISCARD constexpr bool _In_range(const _Ty _Value) noexcept {
  static_assert(_Is_standard_integer<_Rx> && _Is_standard_integer<_Ty>,

stl/inc/xmemory

@@ -10,8 +10,8 @@
 #include <cstdint>
 #include <cstdlib>
 #include <new>
-#include <utility>
 #include <xatomic.h>
+#include <xtr1common>
 #include <xutility>
 
 #if _HAS_CXX20

stl/inc/xtr1common

@@ -244,6 +244,16 @@ struct remove_cvref {
 };
 #endif // _HAS_CXX20
 
+template <class _Ty>
+_NODISCARD constexpr _Ty _Max_limit() noexcept { // same as (numeric_limits<_Ty>::max)(), less throughput cost
+ _STL_INTERNAL_STATIC_ASSERT(is_integral_v<_Ty>); // doesn't attempt to handle all types
+ if constexpr (static_cast<_Ty>(-1) < _Ty{0}) {
+ return ~_Ty{-128 * (_Ty{1} << ((sizeof(_Ty) - 1) * 8))}; // Signed type, form 0x80..0 then bitwise negate
+ } else {
+ return static_cast<_Ty>(-1); // Unsigned tpye
+ }
+}
+
 _STD_END
 
 // TRANSITION, non-_Ugly attribute tokens