remove concepts, collapse unnecessary sfinae

Author: vinay-deshmukh

libcxx/include/__tree

@@ -1218,67 +1218,45 @@ private:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __move_assign_alloc(__tree&, false_type) _NOEXCEPT {}
 
 
-// todo; mark consteval?
-// #ifdef FAKE_VINAY
+// todo; remove
+#ifdef FAKE_VINAY
 
   template <class _From, class _ValueT = _Tp, 
   __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0
 
-// , typename = std::enable_if_t<
-//               !std::is_copy_constructible_v<
-//                   std::remove_cvref_t<decltype(std::declval<_From>().first)>
-//               >
-//             >
+, typename = std::enable_if_t<
+              !std::is_copy_constructible_v<
+                  std::remove_cvref_t<decltype(std::declval<_From>().first)>
+              >
+            >
   >
-  requires (!std::is_copy_constructible_v<
-            std::remove_cvref_t<decltype(std::declval<_From>().first)>
-          >)
+  // requires (!std::is_copy_constructible_v<
+  //           std::remove_cvref_t<decltype(std::declval<_From>().first)>
+  //         >)
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __move_from_value_type(
      __get_node_value_type_t<value_type>& __lhs, _From&& __rhs/*, false_type*/) _NOEXCEPT {
-      (void)__lhs;
-      (void)__rhs;
-      // static_assert(false, "Can not move from a pair<const T, U>");
-      // TODO: how do I flag this code to NOT run at compile time?
-      // Using static_assert means this can't compile _at all_, regardless of whether this code is actually going to execute at compile time or not
   }
 
   template <class _From, class _ValueT = _Tp, 
   __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0
 
   // Check if first type can be copy constructed
 
-// , typename = std::enable_if_t<
-//               std::is_copy_constructible_v<
-//                   std::remove_cvref_t<decltype(std::declval<_From>().first)>
-//               >
-//             >
+, typename = std::enable_if_t<
+              std::is_copy_constructible_v<
+                  std::remove_cvref_t<decltype(std::declval<_From>().first)>
+              >
+            >
   >
-  requires ( std::is_copy_constructible_v<
-            std::remove_cvref_t<decltype(std::declval<_From>().first)>
-          >)
+  // requires ( std::is_copy_constructible_v<
+  //           std::remove_cvref_t<decltype(std::declval<_From>().first)>
+  //         >)
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __move_from_value_type(
      __get_node_value_type_t<value_type>& __lhs, _From&& __rhs/*, true_type*/) _NOEXCEPT {
 
 
-      // const_cast is not allowed at constexpr time.
-      // we get around this by deleting __lhs and creating a new node in-place
-      // to avoid const_cast -ing __lhs.first
-
-      // note: this does not work for `const MoveOnly` keys at constexpr time
-
-
-      __node_allocator& __na = __node_alloc();
-      __node_traits::destroy(__na, std::addressof(__lhs));
-
-      // __get_node_value_type_t<value_type> __tmp(__rhs);
-      using __node_value_type = __get_node_value_type_t<value_type>;
-      __node_value_type __tmp(__rhs.first, __rhs.second);
-      __node_traits::construct(__na, std::addressof(__lhs), std::move(__tmp));
-
-
-
   }
-  // #endif
+  #endif
 
 
 
@@ -1295,9 +1273,37 @@ error: no matching constructor for initialization of '__get_node_value_type_t<va
 # |  1225 |       __get_node_value_type_t<value_type> __tmp(__rhs.first, __rhs.second);
      */
     if (__libcpp_is_constant_evaluated()) {
-      __move_from_value_type(__lhs, __rhs
+      // __move_from_value_type(__lhs, __rhs
       // , integral_constant<bool, is_copy_constructible_v<_From> >()
-      );
+      // );
+
+      if constexpr (integral_constant<bool, is_copy_constructible_v<_From> >()) {
+
+      // const_cast is not allowed at constexpr time.
+      // we get around this by deleting __lhs and creating a new node in-place
+      // to avoid const_cast -ing __lhs.first
+
+      // note: this does not work for `const MoveOnly` keys at constexpr time
+
+
+      __node_allocator& __na = __node_alloc();
+      __node_traits::destroy(__na, std::addressof(__lhs));
+
+      // __get_node_value_type_t<value_type> __tmp(__rhs);
+      using __node_value_type = __get_node_value_type_t<value_type>;
+      __node_value_type __tmp(__rhs.first, __rhs.second);
+      __node_traits::construct(__na, std::addressof(__lhs), std::move(__tmp));
+
+
+      } else {
+
+      // (void)__lhs;
+      // (void)__rhs;
+      // static_assert(false, "Can not move from a pair<const T, U>");
+      // TODO: how do I flag this code to NOT run at compile time?
+      // Using static_assert means this can't compile _at all_, regardless of whether this code is actually going to execute at compile time or not
+
+      }