Expanded C++20 concepts, added C++23 std::unreachable, fixed issues with is_destructible

Author: ZERICO2005

src/libcxx/include/concepts

@@ -1,30 +1,56 @@
-// -*- C++ -*-
-#ifndef _EZCXX_CONCEPTS
-#define _EZCXX_CONCEPTS
-
-#include <type_traits>
-
-#pragma clang system_header
-
-namespace std {
-
-template <class _Tp, class _Up>
-concept same_as = is_same<_Tp, _Up>::value && is_same<_Up, _Tp>::value;
-
-// arithmetic:
-
-template <class _Tp>
-concept integral = is_integral_v<_Tp>;
-
-template <class _Tp>
-concept signed_integral = integral<_Tp> && is_signed_v<_Tp>;
-
-template <class _Tp>
-concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>;
-
-template <class _Tp>
-concept floating_point = is_floating_point_v<_Tp>;
-
-} // namespace std
-
-#endif // _EZCXX_CONCEPTS
+// -*- C++ -*-
+#ifndef _EZCXX_CONCEPTS
+#define _EZCXX_CONCEPTS
+
+#include <type_traits>
+
+#pragma clang system_header
+
+namespace std {
+
+template<class _Tp, class _Up>
+concept same_as = is_same<_Tp, _Up>::value && is_same<_Up, _Tp>::value;
+
+template<class _From, class _To>
+concept convertible_to =
+    is_convertible_v<_From, _To> &&
+    requires { static_cast<_To>(std::declval<_From>()); };
+
+template <class _Dp, class _Bp>
+concept derived_from =
+    is_base_of_v<_Bp, _Dp> &&
+    is_convertible_v<const volatile _Dp*, const volatile _Bp*>;
+
+template<class _Tp>
+concept destructible = is_nothrow_destructible_v<_Tp>;
+
+template<class _Tp, class... _Args>
+concept constructible_from =
+    destructible<_Tp> && is_constructible_v<_Tp, _Args...>;
+
+template<class _Tp>
+concept integral = is_integral_v<_Tp>;
+
+template<class _Tp>
+concept signed_integral = integral<_Tp> && is_signed_v<_Tp>;
+
+template<class _Tp>
+concept unsigned_integral = integral<_Tp> && !signed_integral<_Tp>;
+
+template<class _Tp>
+concept floating_point = is_floating_point_v<_Tp>;
+
+template<class _Tp>
+concept move_constructible =
+    constructible_from<_Tp, _Tp> && std::convertible_to<_Tp, _Tp>;
+
+template<class _Tp>
+concept copy_constructible =
+    move_constructible<_Tp> &&
+    constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp> &&
+    constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp> &&
+    constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
+
+} // namespace std
+
+#endif // _EZCXX_CONCEPTS

src/libcxx/include/type_traits

@@ -447,20 +447,36 @@ template<class _Tp> using is_nothrow_move_assignable = is_nothrow_assignable<add
                                                                              add_rvalue_reference_t<_Tp>>;
 template<class _Tp> inline constexpr bool is_nothrow_move_assignable_v = is_nothrow_move_assignable<_Tp>::value;
 
+/* Clang 16.0.0 required */
+#if 0
 #if __has_builtin(__is_destructible)
 template<class _Tp> inline constexpr bool is_destructible_v = __is_destructible(_Tp);
 template<class _Tp> using is_destructible = bool_constant<is_destructible_v<_Tp>>;
 #endif
+#elif __cplusplus >= 201907L
+template<typename _Tp> struct is_destructible
+    : std::integral_constant<bool, requires(_Tp _Object) { _Object.~_Tp(); }>
+{};
+template<class _Tp> inline constexpr bool is_destructible_v = is_destructible<_Tp>::value;
+#endif
 
 #if __has_builtin(__is_trivially_destructible)
 template<class _Tp> inline constexpr bool is_trivially_destructible_v = __is_trivially_destructible(_Tp);
 template<class _Tp> using is_trivially_destructible = bool_constant<is_trivially_destructible_v<_Tp>>;
 #endif
 
+/* Clang 16.0.0 required */
+#if 0
 #if __has_builtin(__is_nothrow_destructible)
 template<class _Tp> inline constexpr bool is_nothrow_destructible_v = __is_nothrow_destructible(_Tp);
 template<class _Tp> using is_nothrow_destructible = bool_constant<is_nothrow_destructible_v<_Tp>>;
 #endif
+#elif __cplusplus >= 201907L
+template<typename _Tp> struct is_nothrow_destructible
+    : std::integral_constant<bool, requires(_Tp _Object) { {_Object.~_Tp()} noexcept; }>
+{};
+template<class _Tp> inline constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<_Tp>::value;
+#endif
 
 #if __has_builtin(__has_virtual_destructor)
 template<class _Tp> inline constexpr bool has_virtual_destructor_v = __has_virtual_destructor(_Tp);

src/libcxx/include/utility

@@ -33,6 +33,8 @@ template<class _Tp> _EZCXX_INLINE constexpr std::add_const_t<_Tp>& as_const(_Tp&
 template<class _Tp> _EZCXX_INLINE constexpr auto as_const(_Tp const&& __value) noexcept = delete;
 #endif // __cplusplus > 201103L
 
+[[noreturn]] inline void unreachable() { __builtin_unreachable(); }
+
 } // namespace std
 
 #endif // _EZCXX_UTILITY

src/libcxx/include/version

@@ -213,7 +213,7 @@
 // # define __cpp_lib_string_resize_and_overwrite          202110L
 // # define __cpp_lib_to_underlying                        202102L
 // # define __cpp_lib_tuple_like                           202207L
-// # define __cpp_lib_unreachable                          202202L
+# define __cpp_lib_unreachable                          202202L
 #endif // __cplusplus >= 202302L
 
 #endif // _EZCXX_VERSION