From 2e776ad155538de3469543176dc05bfbb3e375a9 Mon Sep 17 00:00:00 2001
From: joaquintides <joaquin@tid.es>
Date: Wed, 28 Sep 2022 17:53:58 +0200
Subject: [PATCH] fixed clear

---
 include/boost/unordered/detail/foa.hpp | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index 26123e37..822b49ac 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -755,7 +755,20 @@ public:
 
   void clear()noexcept
   {
-    for_all_elements([this](value_type* p){destroy_element(p);});
+    auto pg=arrays.groups;
+    auto p=arrays.elements;
+    if(p){
+      for(std::size_t pos=0,last=arrays.groups_size_mask+1;
+          pos!=last;++pos,++pg,p+=N){
+        auto mask=pg->match_really_occupied();
+        while(mask){
+          auto n=unchecked_countr_zero(mask);
+          destroy_element(p+n);
+          pg->reset(n);
+          mask&=mask-1;
+        }
+      }
+    }
     size_=0;
   }