[libc++] Simplify the generic implementation of is_{un}signed (#136095)

Author: philnik777

libcxx/include/__type_traits/is_signed.h

@@ -12,7 +12,6 @@
 #include <__config>
 #include <__type_traits/integral_constant.h>
 #include <__type_traits/is_arithmetic.h>
-#include <__type_traits/is_integral.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -32,24 +31,18 @@ _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_signed_v = __is_signed(_Tp);
 
 #else // __has_builtin(__is_signed)
 
-template <class _Tp, bool = is_integral<_Tp>::value>
-struct __libcpp_is_signed_impl : _BoolConstant<(_Tp(-1) < _Tp(0))> {};
-
-template <class _Tp>
-struct __libcpp_is_signed_impl<_Tp, false> : true_type {}; // floating point
-
 template <class _Tp, bool = is_arithmetic<_Tp>::value>
-struct __libcpp_is_signed : __libcpp_is_signed_impl<_Tp> {};
+inline constexpr bool __is_signed_v = false;
 
 template <class _Tp>
-struct __libcpp_is_signed<_Tp, false> : false_type {};
+inline constexpr bool __is_signed_v<_Tp, true> = _Tp(-1) < _Tp(0);
 
 template <class _Tp>
-struct is_signed : __libcpp_is_signed<_Tp> {};
+struct is_signed : integral_constant<bool, __is_signed_v<_Tp>> {};
 
 #  if _LIBCPP_STD_VER >= 17
 template <class _Tp>
-inline constexpr bool is_signed_v = is_signed<_Tp>::value;
+inline constexpr bool is_signed_v = __is_signed_v<_Tp>;
 #  endif
 
 #endif // __has_builtin(__is_signed)

libcxx/include/__type_traits/is_unsigned.h

@@ -11,7 +11,6 @@
 
 #include <__config>
 #include <__type_traits/integral_constant.h>
-#include <__type_traits/is_arithmetic.h>
 #include <__type_traits/is_integral.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -33,23 +32,17 @@ _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool is_unsigned_v = __is_unsigned(_
 #else // __has_builtin(__is_unsigned)
 
 template <class _Tp, bool = is_integral<_Tp>::value>
-struct __libcpp_is_unsigned_impl : public _BoolConstant<(_Tp(0) < _Tp(-1))> {};
+inline constexpr bool __is_unsigned_v = false;
 
 template <class _Tp>
-struct __libcpp_is_unsigned_impl<_Tp, false> : public false_type {}; // floating point
-
-template <class _Tp, bool = is_arithmetic<_Tp>::value>
-struct __libcpp_is_unsigned : public __libcpp_is_unsigned_impl<_Tp> {};
-
-template <class _Tp>
-struct __libcpp_is_unsigned<_Tp, false> : public false_type {};
+inline constexpr bool __is_unsigned_v<_Tp, true> = _Tp(0) < _Tp(-1);
 
 template <class _Tp>
-struct is_unsigned : public __libcpp_is_unsigned<_Tp> {};
+struct is_unsigned : integral_constant<bool, __is_unsigned_v<_Tp>> {};
 
 #  if _LIBCPP_STD_VER >= 17
 template <class _Tp>
-inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
+inline constexpr bool is_unsigned_v = __is_unsigned_v<_Tp>;
 #  endif
 
 #endif // __has_builtin(__is_unsigned)