Fixed std::initializer_list assignment issues for open-addressing containers (#277)

* fixed #276

* used range insert, stylistic this->

* assigned non-empty std::initializer_lists

include/boost/unordered/unordered_flat_map.hpp

@@ -1,4 +1,5 @@
 // Copyright (C) 2022-2023 Christian Mazakas
+// Copyright (C) 2024 Joaquin M Lopez Munoz
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
@@ -202,6 +203,13 @@ namespace boost {
         return *this;
       }
 
+      unordered_flat_map& operator=(std::initializer_list<value_type> il)
+      {
+        this->clear();
+        this->insert(il.begin(), il.end());
+        return *this;
+      }
+
       allocator_type get_allocator() const noexcept
       {
         return table_.get_allocator();

include/boost/unordered/unordered_flat_set.hpp

@@ -1,4 +1,5 @@
 // Copyright (C) 2022-2023 Christian Mazakas
+// Copyright (C) 2024 Joaquin M Lopez Munoz
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
@@ -198,6 +199,13 @@ namespace boost {
         return *this;
       }
 
+      unordered_flat_set& operator=(std::initializer_list<value_type> il)
+      {
+        this->clear();
+        this->insert(il.begin(), il.end());
+        return *this;
+      }
+
       allocator_type get_allocator() const noexcept
       {
         return table_.get_allocator();

include/boost/unordered/unordered_node_map.hpp

@@ -210,6 +210,13 @@ namespace boost {
         return *this;
       }
 
+      unordered_node_map& operator=(std::initializer_list<value_type> il)
+      {
+        this->clear();
+        this->insert(il.begin(), il.end());
+        return *this;
+      }
+
       allocator_type get_allocator() const noexcept
       {
         return table_.get_allocator();

include/boost/unordered/unordered_node_set.hpp

@@ -208,6 +208,13 @@ namespace boost {
         return *this;
       }
 
+      unordered_node_set& operator=(std::initializer_list<value_type> il)
+      {
+        this->clear();
+        this->insert(il.begin(), il.end());
+        return *this;
+      }
+
       allocator_type get_allocator() const noexcept
       {
         return table_.get_allocator();