Add Unordered patch for 1.83.0

feed/history/boost_1_83_0.qbk

@@ -28,6 +28,10 @@ in the release.
   * Compilation on Windows ARM platforms may fail for missing intrinsics, see [github json 926] and [github json 927].
     [@https://github.com/boostorg/json/commit/c4ce8509d015a0b75cfa9d36609b8409821a9c86.patch Patch].
 
+* Unordered
+  * Fix erroneous copy assigment operator that would destroy non-existent elements, see [github unordered 205].
+    [@patches/1_83_0/0001-unordered-fix-copy-assign.patch Patch].
+
 [endsect]
 
 [section New Libraries]

patches/1_83_0/0001-unordered-fix-copy-assign.patch

@@ -0,0 +1,16 @@
+diff --git a/include/boost/unordered/detail/foa/core.hpp b/include/boost/unordered/detail/foa/core.hpp
+index 239d05d3..7ae9f2c8 100644
+--- a/include/boost/unordered/detail/foa/core.hpp
++++ b/include/boost/unordered/detail/foa/core.hpp
+@@ -1870,9 +1870,10 @@ private:
+ 
+   void fast_copy_elements_from(const table_core& x)
+   {
+-    if(arrays.elements){
++    if(arrays.elements&&x.arrays.elements){
+       copy_elements_array_from(x);
+       copy_groups_array_from(x);
++      size_ctrl.ml=std::size_t(x.size_ctrl.ml);
+       size_ctrl.size=std::size_t(x.size_ctrl.size);
+     }
+   }

patches/index.html

@@ -33,6 +33,12 @@ https://www.boost.org/development/website_updating.html
               late to be fixed in the release. Be careful as they have
               not been through the normal testing process.</p>
 
+            <h2>1.83.0</h2>
+
+            <ul>
+              <li><a href="1_83_0/0001-unordered-fix-copy-assign.patch">0001-unordered-fix-copy-assign.patch</a></li>
+            </ul>
+
             <h2>1.82.0</h2>
 
             <ul>