From d233d838114634d38e183d1d32feaccc2528e42a Mon Sep 17 00:00:00 2001
From: joaquintides <joaquin@tid.es>
Date: Wed, 5 Oct 2022 14:49:42 +0200
Subject: [PATCH] allow 100% fillup for small capacities

---
 include/boost/unordered/detail/foa.hpp | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index 1744798a..1777da49 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -1195,10 +1195,15 @@ private:
 
   std::size_t max_load()const
   {
-    float fml=mlf*(float)(capacity());
-    auto  res=(std::numeric_limits<std::size_t>::max)();
-    if(res>(std::size_t)fml)res=(std::size_t)fml;
-    return res;
+    static constexpr std::size_t small_capacity=2*N-1;
+
+    auto capacity_=capacity();
+    if(capacity_<=small_capacity){
+      return capacity_; /* we allow 100% usage */
+    }
+    else{
+      return (std::size_t)(mlf*(float)(capacity_));
+    }
   }
 
   static inline auto key_from(const value_type& x)