formatting redo

Author: vinay-deshmukh

libcxx/include/__tree

@@ -1079,10 +1079,10 @@ public:
 #if _LIBCPP_STD_VER >= 26
     if (std::is_constant_evaluated() && std::is_copy_constructible_v<decltype(__value.first)>) {
       // We create a sfinae wrapper method here, because if the __emplace_hint_unique method gets template instantiated
-      // within __insert_unique_from_orphaned_node, the code will fail to compile where the value is not
-      // copy_constructible for runtime execution as well; unless we use `if constexpr`. Given the copy-constructible
+      // within __insert_unique_from_orphaned_node, the code will fail to compile when the value is not
+      // copy_constructible (even for runtime execution); unless we use `if constexpr`. Given the copy-constructible
       // code path will be a performance regression, we want to restrict it to only execute during constant evaluation
-      //, we need to delay the template instantiation
+      // , hence, we need to delay the template instantiation.
       __emplace_hint_unique__sfinae(
           integral_constant< bool, std::is_copy_constructible_v<decltype(__value.first)> >(),
           __p,
@@ -1434,7 +1434,7 @@ private:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
   __assign_value__sfinae(false_type, __get_node_value_type_t<value_type>&, _From&&) {
     // This method body should never be run. It only exists to allow for compilation. See note in __assign_value for
-    // more information
+    // more information.
   }
 
   template <class _From, class _ValueT = _Tp, __enable_if_t<__is_tree_value_type_v<_ValueT>, int> = 0>
@@ -1445,22 +1445,23 @@ private:
 #if _LIBCPP_STD_VER >= 26
 
     if (std::is_constant_evaluated() && std::is_copy_constructible_v<decltype(__rhs.first)>) {
-      // we use copy, and not "move" as the constraint
-      // because we can NOT move from `const key_type`, which is how `value_type` is defined
-      // atleast for map
-      // typedef pair<const key_type, mapped_type> value_type;
-      // so we must copy it
-
-      // 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 __lhs.first
-
-      // We create a sfinae wrapper method here, because if the body of the true_type overload for
-      // __assign_value__sfinae() gets template instantiated within __assign_value, the code will fail to compile where
-      // the value is not copy_constructible for runtime execution as well; unless we use `if constexpr`. Given the
-      // copy-constructible code path will be a performance regression, we want to restrict it to only execute during
-      // constant evaluation
-      //, we need to delay the template instantiation
+      // We use copy, and not "move" as the constraint here because we can NOT move
+      // from `const key_type`, which is how `value_type` is defined for `std::map`
+      // `typedef pair<const key_type, mapped_type> value_type;`
+      // so we must copy it to not perform undefined behavior which
+      // is disallowed during constant evaluation.
+
+      // Furthermore, `const_cast` is not allowed during constant evaluation.
+      // We get around this by deleting `__lhs` and creating a new node in-place
+      // to avoid the `const_cast` when attempting to assign to `__lhs.first`.
+
+      // We create a sfinae wrapper method here, because if the body of the `true_type` overload for
+      // `__assign_value__sfinae()` gets template instantiated within `__assign_value`,
+      // the code will fail to compile when
+      // the value is not copy_constructible (even for runtime execution); unless we use `if constexpr`.
+      // Given that the copy-constructible code path will be a performance regression,
+      // we want to restrict it to only execute during constant evaluation
+      //, we need to delay the template instantiation.
 
       __assign_value__sfinae(std::integral_constant<bool, std::is_copy_constructible_v<decltype(__rhs.first)>>(),
                              std::forward<decltype(__lhs)>(__lhs),