removed overzealous inlines

(possible performance impact)

.appveyor.yml

@@ -42,7 +42,12 @@ environment:
 
     - FLAVOR: Visual Studio 2017
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-      B2_CXXSTD: 14,17,latest
+      B2_CXXSTD: 14,17
+      B2_TOOLSET: msvc-14.1
+
+    - FLAVOR: Visual Studio 2017
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      B2_CXXSTD: latest
       B2_TOOLSET: msvc-14.1
 
     - FLAVOR: cygwin (32-bit)
@@ -63,7 +68,7 @@ environment:
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
       ADDPATH: C:\cygwin64\bin;
       B2_ADDRESS_MODEL: 64
-      B2_CXXSTD: 03,11
+      B2_CXXSTD: 03
       B2_TOOLSET: gcc
       B2_FLAGS: "include=libs/unordered/test/unordered include=libs/unordered/test/exception"
 
@@ -71,21 +76,51 @@ environment:
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
       ADDPATH: C:\cygwin64\bin;
       B2_ADDRESS_MODEL: 64
-      B2_CXXSTD: 14,1z
+      B2_CXXSTD: 11
+      B2_TOOLSET: gcc
+      B2_FLAGS: "include=libs/unordered/test/unordered include=libs/unordered/test/exception"
+
+    - FLAVOR: cygwin (64-bit, latest)
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
+      ADDPATH: C:\cygwin64\bin;
+      B2_ADDRESS_MODEL: 64
+      B2_CXXSTD: 14
+      B2_TOOLSET: gcc
+      B2_FLAGS: "include=libs/unordered/test/unordered include=libs/unordered/test/exception"
+
+    - FLAVOR: cygwin (64-bit, latest)
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022
+      ADDPATH: C:\cygwin64\bin;
+      B2_ADDRESS_MODEL: 64
+      B2_CXXSTD: 1z
       B2_TOOLSET: gcc
       B2_FLAGS: "include=libs/unordered/test/unordered include=libs/unordered/test/exception"
 
     - FLAVOR: mingw-w64, 32 bit
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       ADDPATH: C:\mingw-w64\i686-8.1.0-posix-dwarf-rt_v6-rev0\mingw32\bin;
-      B2_CXXSTD: 03,11,14,17,2a
+      B2_CXXSTD: 03,11,14
+      B2_TOOLSET: gcc
+      B2_ADDRESS_MODEL: 32
+
+    - FLAVOR: mingw-w64, 32 bit
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      ADDPATH: C:\mingw-w64\i686-8.1.0-posix-dwarf-rt_v6-rev0\mingw32\bin;
+      B2_CXXSTD: 17,2a
       B2_TOOLSET: gcc
       B2_ADDRESS_MODEL: 32
 
     - FLAVOR: mingw-w64, 64 bit
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       ADDPATH: C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin;
-      B2_CXXSTD: 03,11,14,17,2a
+      B2_CXXSTD: 03,11,14
+      B2_TOOLSET: gcc
+      B2_ADDRESS_MODEL: 64
+
+    - FLAVOR: mingw-w64, 64 bit
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      ADDPATH: C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin;
+      B2_CXXSTD: 17,2a
       B2_TOOLSET: gcc
       B2_ADDRESS_MODEL: 64
 

.drone.jsonnet

@@ -32,6 +32,7 @@ local linux_pipeline(name, image, environment, packages = "", sources = [], arch
             commands:
             [
                 'set -e',
+                'uname -a',
                 'wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add -',
             ] +
             (if sources != [] then [ ('apt-add-repository "' + source + '"') for source in sources ] else []) +
@@ -63,6 +64,7 @@ local macos_pipeline(name, environment, xcode_version = "12.2", osx_version = "c
             environment: environment + { "DEVELOPER_DIR": "/Applications/Xcode-" + xcode_version + ".app/Contents/Developer" },
             commands:
             [
+                'uname -a',
                 'export LIBRARY=' + library,
                 './.drone/drone.sh',
             ]
@@ -89,6 +91,7 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
             environment: environment,
             commands:
             [
+                'echo $env:DRONE_STAGE_MACHINE',
                 'cmd /C .drone\\\\drone.bat ' + library,
             ]
         }
@@ -168,8 +171,9 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     macos_pipeline(
-        "MacOS 10.15 Xcode 12.2 ASAN",
+        "MacOS 12.4 Xcode 13.4.1 ASAN",
         { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + asan,
+        xcode_version = "13.4.1", osx_version = "monterey",
     ),
 
     windows_pipeline(

.drone/drone.sh

@@ -5,6 +5,7 @@
 # https://www.boost.org/LICENSE_1_0.txt
 
 set -ex
+export PATH=~/.local/bin:/usr/local/bin:$PATH
 
 DRONE_BUILD_DIR=$(pwd)
 

doc/unordered/unordered_map.adoc

@@ -1566,7 +1566,9 @@ Effects:;; Changes the container's maximum load factor, using `z` as a hint.
 void rehash(size_type n);
 ```
 
-Changes the number of buckets so that there at least `n` buckets, and so that the load factor is less than the maximum load factor.
+Changes the number of buckets so that there are at least `n` buckets, and so that the load factor is less than or equal to the maximum load factor. When applicable, this will either grow or shrink the `bucket_count()` associated with the container.
+
+When `size() == 0`, `rehash(0)` will deallocate the underlying buckets array.
 
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
@@ -1580,6 +1582,10 @@ Throws:;; The function has no effect if an exception is thrown, unless it is thr
 void reserve(size_type n);
 ```
 
+Equivalent to `a.rehash(ceil(n / a.max_load_factor()))`, or `a.rehash(1)` if `n > 0` and `a.max_load_factor() == std::numeric_limits<float>::infinity()`.
+
+Similar to `rehash`, this function can be used to grow or shrink the number of buckets in the container.
+
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
 [horizontal]

doc/unordered/unordered_multimap.adoc

@@ -1345,7 +1345,9 @@ Effects:;; Changes the container's maximum load factor, using `z` as a hint.
 void rehash(size_type n);
 ```
 
-Changes the number of buckets so that there at least `n` buckets, and so that the load factor is less than the maximum load factor.
+Changes the number of buckets so that there are at least `n` buckets, and so that the load factor is less than or equal to the maximum load factor. When applicable, this will either grow or shrink the `bucket_count()` associated with the container.
+
+When `size() == 0`, `rehash(0)` will deallocate the underlying buckets array.
 
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
@@ -1359,6 +1361,10 @@ Throws:;; The function has no effect if an exception is thrown, unless it is thr
 void reserve(size_type n);
 ```
 
+Equivalent to `a.rehash(ceil(n / a.max_load_factor()))`, or `a.rehash(1)` if `n > 0` and `a.max_load_factor() == std::numeric_limits<float>::infinity()`.
+
+Similar to `rehash`, this function can be used to grow or shrink the number of buckets in the container.
+
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
 [horizontal]

doc/unordered/unordered_multiset.adoc

@@ -1306,7 +1306,9 @@ Effects:;; Changes the container's maximum load factor, using `z` as a hint.
 void rehash(size_type n);
 ```
 
-Changes the number of buckets so that there at least `n` buckets, and so that the load factor is less than the maximum load factor.
+Changes the number of buckets so that there are at least `n` buckets, and so that the load factor is less than or equal to the maximum load factor. When applicable, this will either grow or shrink the `bucket_count()` associated with the container.
+
+When `size() == 0`, `rehash(0)` will deallocate the underlying buckets array.
 
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
@@ -1320,11 +1322,16 @@ Throws:;; The function has no effect if an exception is thrown, unless it is thr
 void reserve(size_type n);
 ```
 
+Equivalent to `a.rehash(ceil(n / a.max_load_factor()))`, or `a.rehash(1)` if `n > 0` and `a.max_load_factor() == std::numeric_limits<float>::infinity()`.
+
+Similar to `rehash`, this function can be used to grow or shrink the number of buckets in the container.
+
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
 [horizontal]
 Throws:;; The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.
 
+
 ---
 
 === Equality Comparisons

doc/unordered/unordered_set.adoc

@@ -1329,7 +1329,9 @@ Effects:;; Changes the container's maximum load factor, using `z` as a hint.
 void rehash(size_type n);
 ```
 
-Changes the number of buckets so that there at least `n` buckets, and so that the load factor is less than the maximum load factor.
+Changes the number of buckets so that there are at least `n` buckets, and so that the load factor is less than or equal to the maximum load factor. When applicable, this will either grow or shrink the `bucket_count()` associated with the container.
+
+When `size() == 0`, `rehash(0)` will deallocate the underlying buckets array.
 
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
@@ -1343,11 +1345,16 @@ Throws:;; The function has no effect if an exception is thrown, unless it is thr
 void reserve(size_type n);
 ```
 
+Equivalent to `a.rehash(ceil(n / a.max_load_factor()))`, or `a.rehash(1)` if `n > 0` and `a.max_load_factor() == std::numeric_limits<float>::infinity()`.
+
+Similar to `rehash`, this function can be used to grow or shrink the number of buckets in the container.
+
 Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.
 
 [horizontal]
 Throws:;; The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.
 
+
 === Equality Comparisons
 
 ==== operator==

include/boost/unordered/detail/fca.hpp

@@ -494,11 +494,33 @@ namespace boost {
         group_pointer groups;
 
       public:
+        static std::size_t bucket_count_for(std::size_t num_buckets)
+        {
+          if (num_buckets == 0) {
+            return 0;
+          }
+          return size_policy::size(size_policy::size_index(num_buckets));
+        }
+
+        grouped_bucket_array()
+            : empty_value<node_allocator_type>(
+                empty_init_t(), node_allocator_type()),
+              size_index_(0), size_(0), buckets(), groups()
+        {
+        }
+
         grouped_bucket_array(size_type n, const Allocator& al)
             : empty_value<node_allocator_type>(empty_init_t(), al),
-              size_index_(size_policy::size_index(n)),
-              size_(size_policy::size(size_index_)), buckets(), groups()
+              size_index_(0),
+              size_(0), buckets(), groups()
         {
+          if (n == 0) {
+            return;
+          }
+
+          size_index_ = size_policy::size_index(n);
+          size_ = size_policy::size(size_index_);
+
           bucket_allocator_type bucket_alloc = this->get_bucket_allocator();
           group_allocator_type group_alloc = this->get_group_allocator();
 
@@ -646,7 +668,7 @@ namespace boost {
 
         size_type bucket_count() const { return size_; }
 
-        iterator begin() const { return ++at(size_); }
+        iterator begin() const { return size_ == 0 ? end() : ++at(size_); }
 
         iterator end() const
         {
@@ -660,6 +682,10 @@ namespace boost {
 
         local_iterator begin(size_type n) const
         {
+          if (size_ == 0) {
+            return this->end(n);
+          }
+
           return local_iterator(
             (buckets + static_cast<difference_type>(n))->next);
         }
@@ -670,12 +696,16 @@ namespace boost {
 
         iterator at(size_type n) const
         {
-          std::size_t const N = group::N;
+          if (size_ > 0) {
+            std::size_t const N = group::N;
 
-          iterator pbg(buckets + static_cast<difference_type>(n),
-            groups + static_cast<difference_type>(n / N));
+            iterator pbg(buckets + static_cast<difference_type>(n),
+              groups + static_cast<difference_type>(n / N));
 
-          return pbg;
+            return pbg;
+          } else {
+            return this->end();
+          }
         }
 
         span<Bucket> raw()

include/boost/unordered/detail/implementation.hpp

@@ -47,6 +47,7 @@
 #include <boost/type_traits/make_void.hpp>
 #include <boost/type_traits/remove_const.hpp>
 #include <boost/unordered/detail/fca.hpp>
+#include <boost/unordered/detail/type_traits.hpp>
 #include <boost/unordered/detail/fwd.hpp>
 #include <boost/utility/addressof.hpp>
 #include <boost/utility/enable_if.hpp>
@@ -200,7 +201,7 @@ namespace boost {
       template <typename Types> struct table;
 
       static const float minimum_max_load_factor = 1e-3f;
-      static const std::size_t default_bucket_count = 11;
+      static const std::size_t default_bucket_count = 0;
 
       struct move_tag
       {
@@ -618,39 +619,6 @@ namespace boost {
 
 #endif
 
-////////////////////////////////////////////////////////////////////////////
-// Type checkers used for the transparent member functions added by C++20 and up
-
-      template <class, class = void> struct is_transparent : public false_type
-      {
-      };
-
-      template <class T>
-      struct is_transparent<T,
-        typename boost::make_void<typename T::is_transparent>::type>
-          : public true_type
-      {
-      };
-
-      template <class, class A, class B> struct are_transparent
-      {
-        static bool const value =
-          is_transparent<A>::value && is_transparent<B>::value;
-      };
-
-      template <class Key, class UnorderedMap> struct transparent_non_iterable
-      {
-        typedef typename UnorderedMap::hasher hash;
-        typedef typename UnorderedMap::key_equal key_equal;
-        typedef typename UnorderedMap::iterator iterator;
-        typedef typename UnorderedMap::const_iterator const_iterator;
-
-        static bool const value =
-          are_transparent<Key, hash, key_equal>::value &&
-          !boost::is_convertible<Key, iterator>::value &&
-          !boost::is_convertible<Key, const_iterator>::value;
-      };
-
 ////////////////////////////////////////////////////////////////////////////
 // Explicitly call a destructor
 
@@ -2054,12 +2022,14 @@ namespace boost {
 
         std::size_t bucket_size(std::size_t index) const
         {
-          bucket_iterator itb = buckets_.at(index);
-          node_pointer n = itb->next;
           std::size_t count = 0;
-          while (n) {
-            ++count;
-            n = n->next;
+          if (size_ > 0) {
+            bucket_iterator itb = buckets_.at(index);
+            node_pointer n = itb->next;
+            while (n) {
+              ++count;
+              n = n->next;
+            }
           }
           return count;
         }
@@ -2069,13 +2039,18 @@ namespace boost {
 
         void recalculate_max_load()
         {
-          using namespace std;
-
           // From 6.3.1/13:
           // Only resize when size >= mlf_ * count
-          max_load_ = boost::unordered::detail::double_to_size(
-            floor(static_cast<double>(mlf_) *
-                 static_cast<double>(buckets_.bucket_count())));
+          std::size_t const bc = buckets_.bucket_count();
+
+          // it's important we do the `bc == 0` check here because the `mlf_`
+          // can be specified to be infinity. The operation `n * INF` is `INF`
+          // for all `n > 0` but NaN for `n == 0`.
+          //
+          max_load_ =
+            bc == 0 ? 0
+                    : boost::unordered::detail::double_to_size(
+                        static_cast<double>(mlf_) * static_cast<double>(bc));
         }
 
         void max_load_factor(float z)
@@ -2088,6 +2063,12 @@ namespace boost {
         ////////////////////////////////////////////////////////////////////////
         // Constructors
 
+        table()
+            : functions(hasher(), key_equal()), size_(0), mlf_(1.0f),
+              max_load_(0)
+        {
+        }
+
         table(std::size_t num_buckets, hasher const& hf, key_equal const& eq,
           node_allocator_type const& a)
             : functions(hf, eq), size_(0), mlf_(1.0f), max_load_(0),
@@ -2359,7 +2340,6 @@ namespace boost {
         template <typename UniqueType>
         void move_assign(table& x, UniqueType is_unique, false_type)
         {
-          reserve(x.size_);
           if (node_alloc() == x.node_alloc()) {
             move_assign_equal_alloc(x);
           } else {
@@ -2388,7 +2368,9 @@ namespace boost {
           {
             mlf_ = x.mlf_;
             recalculate_max_load();
-            this->reserve_for_insert(x.size_);
+            if (x.size_ > 0) {
+              this->reserve_for_insert(x.size_);
+            }
             this->clear_impl();
           }
           BOOST_CATCH(...)
@@ -2420,11 +2402,14 @@ namespace boost {
         node_pointer find_node_impl(
           Key const& x, bucket_iterator itb) const
         {
-          key_equal const& pred = this->key_eq();
-          node_pointer p = itb->next;
-          for (; p; p = p->next) {
-            if (pred(x, extractor::extract(p->value()))) {
-              break;
+          node_pointer p = node_pointer();
+          if (itb != buckets_.end()) {
+            key_equal const& pred = this->key_eq();
+            p = itb->next;
+            for (; p; p = p->next) {
+              if (pred(x, extractor::extract(p->value()))) {
+                break;
+              }
             }
           }
           return p;
@@ -2453,11 +2438,13 @@ namespace boost {
         inline iterator transparent_find(
           Key const& k, Hash const& h, Pred const& pred) const
         {
-          std::size_t const key_hash = h(k);
-          bucket_iterator itb = buckets_.at(buckets_.position(key_hash));
-          for (node_pointer p = itb->next; p; p = p->next) {
-            if (BOOST_LIKELY(pred(k, extractor::extract(p->value())))) {
-              return iterator(p, itb);
+          if (size_ > 0) {
+            std::size_t const key_hash = h(k);
+            bucket_iterator itb = buckets_.at(buckets_.position(key_hash));
+            for (node_pointer p = itb->next; p; p = p->next) {
+              if (BOOST_LIKELY(pred(k, extractor::extract(p->value())))) {
+                return iterator(p, itb);
+              }
             }
           }
 
@@ -2467,11 +2454,13 @@ namespace boost {
         template <class Key>
         node_pointer* find_prev(Key const& key, bucket_iterator itb)
         {
-          key_equal pred = this->key_eq();
-          for (node_pointer* pp = boost::addressof(itb->next); *pp;
-               pp = boost::addressof((*pp)->next)) {
-            if (pred(key, extractor::extract((*pp)->value()))) {
-              return pp;
+          if (size_ > 0) {
+            key_equal pred = this->key_eq();
+            for (node_pointer* pp = boost::addressof(itb->next); *pp;
+                pp = boost::addressof((*pp)->next)) {
+              if (pred(key, extractor::extract((*pp)->value()))) {
+                return pp;
+              }
             }
           }
           typedef node_pointer* node_pointer_pointer;
@@ -2503,6 +2492,17 @@ namespace boost {
           new_buckets.insert_node(itnewb, p);
         }
 
+        static std::size_t min_buckets(std::size_t num_elements, float mlf)
+        {
+          std::size_t num_buckets = static_cast<std::size_t>(
+            std::ceil(static_cast<float>(num_elements) / mlf));
+
+          if (num_buckets == 0 && num_elements > 0) { // mlf == inf
+            num_buckets = 1;
+          }
+          return num_buckets;
+        }
+
         void rehash(std::size_t);
         void reserve(std::size_t);
         void reserve_for_insert(std::size_t);
@@ -3411,22 +3411,18 @@ namespace boost {
       template <typename Types>
       inline void table<Types>::rehash(std::size_t num_buckets)
       {
-        std::size_t bc = (std::max)(num_buckets,
-          static_cast<std::size_t>(1.0f + static_cast<float>(size_) / mlf_));
+        num_buckets = (std::max)(
+          min_buckets(size_, mlf_), buckets_.bucket_count_for(num_buckets));
 
-        if (bc <= buckets_.bucket_count()) {
-          return;
+        if (num_buckets != this->bucket_count()) {
+          this->rehash_impl(num_buckets);
         }
-
-        this->rehash_impl(bc);
       }
 
       template <class Types>
       inline void table<Types>::reserve(std::size_t num_elements)
       {
-        std::size_t const num_buckets = static_cast<std::size_t>(
-          std::ceil(static_cast<float>(num_elements) / mlf_));
-
+        std::size_t num_buckets = min_buckets(num_elements, mlf_);
         this->rehash(num_buckets);
       }
 

include/boost/unordered/detail/type_traits.hpp

@@ -0,0 +1,59 @@
+// Copyright (C) 2022 Christian Mazakas
+//
+// 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)
+
+#ifndef BOOST_UNORDERED_DETAIL_TYPE_TRAITS_HPP
+#define BOOST_UNORDERED_DETAIL_TYPE_TRAITS_HPP
+
+#include <boost/config.hpp>
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/make_void.hpp>
+
+namespace boost {
+  namespace unordered {
+    namespace detail {
+      ////////////////////////////////////////////////////////////////////////////
+      // Type checkers used for the transparent member functions added by C++20
+      // and up
+
+      template <class, class = void>
+      struct is_transparent : public boost::false_type
+      {
+      };
+
+      template <class T>
+      struct is_transparent<T,
+        typename boost::make_void<typename T::is_transparent>::type>
+          : public boost::true_type
+      {
+      };
+
+      template <class, class A, class B> struct are_transparent
+      {
+        static bool const value =
+          is_transparent<A>::value && is_transparent<B>::value;
+      };
+
+      template <class Key, class UnorderedMap> struct transparent_non_iterable
+      {
+        typedef typename UnorderedMap::hasher hash;
+        typedef typename UnorderedMap::key_equal key_equal;
+        typedef typename UnorderedMap::iterator iterator;
+        typedef typename UnorderedMap::const_iterator const_iterator;
+
+        static bool const value =
+          are_transparent<Key, hash, key_equal>::value &&
+          !boost::is_convertible<Key, iterator>::value &&
+          !boost::is_convertible<Key, const_iterator>::value;
+      };
+    } // namespace detail
+  }   // namespace unordered
+} // namespace boost
+
+#endif // BOOST_UNORDERED_DETAIL_TYPE_TRAITS_HPP

include/boost/unordered/detail/xmx.hpp

@@ -0,0 +1,75 @@
+/* 32b/64b xmx mix function.
+ *
+ * Copyright 2022 Peter Dimov.
+ * Copyright 2022 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)
+ *
+ * See https://www.boost.org/libs/unordered for library home page.
+ */
+
+#ifndef BOOST_UNORDERED_DETAIL_XMX_HPP
+#define BOOST_UNORDERED_DETAIL_XMX_HPP
+
+#include <boost/cstdint.hpp>
+#include <climits>
+#include <cstddef>
+
+namespace boost{
+namespace unordered{
+namespace detail{
+
+/* Bit mixer for improvement of statistical properties of hash functions.
+ * The implementation is different on 64bit and 32bit architectures:
+ * 
+ *   - 64bit: same as xmx function in
+ *     http://jonkagstrom.com/bit-mixer-construction/index.html
+ *   - 32bit: generated by Hash Function Prospector
+ *     (https://github.com/skeeto/hash-prospector) and selected as the
+ *     best overall performer in benchmarks of Boost.Unordered flat containers.
+ *     Score assigned by Hash Prospector: 333.7934929677524
+ */
+
+#if defined(SIZE_MAX)
+#if ((((SIZE_MAX >> 16) >> 16) >> 16) >> 15) != 0
+#define BOOST_UNORDERED_64B_ARCHITECTURE /* >64 bits assumed as 64 bits */
+#endif
+#elif defined(UINTPTR_MAX) /* used as proxy for std::size_t */
+#if ((((UINTPTR_MAX >> 16) >> 16) >> 16) >> 15) != 0
+#define BOOST_UNORDERED_64B_ARCHITECTURE
+#endif
+#endif
+
+static inline std::size_t xmx(std::size_t x)noexcept
+{
+#if defined(BOOST_UNORDERED_64B_ARCHITECTURE)
+
+  boost::uint64_t z=(boost::uint64_t)x;
+
+  z^=z>>23;
+  z*=0xff51afd7ed558ccdull;
+  z^=z>>23;
+
+  return (std::size_t)z;
+
+#else /* 32 bits assumed */
+
+  x^=x>>18;
+  x*=0x56b5aaadu;
+  x^=x>>16;
+
+  return x;
+
+#endif
+}
+
+#ifdef BOOST_UNORDERED_64B_ARCHITECTURE
+#undef BOOST_UNORDERED_64B_ARCHITECTURE
+#endif
+
+} /* namespace detail */
+} /* namespace unordered */
+} /* namespace boost */
+
+#endif

include/boost/unordered/hash_traits.hpp

@@ -0,0 +1,44 @@
+/* Hash function characterization.
+ *
+ * Copyright 2022 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)
+ *
+ * See https://www.boost.org/libs/unordered for library home page.
+ */
+
+#ifndef BOOST_UNORDERED_HASH_TRAITS_HPP
+#define BOOST_UNORDERED_HASH_TRAITS_HPP
+
+#include <boost/type_traits/make_void.hpp>
+#include <type_traits>
+
+namespace boost{
+namespace unordered{
+
+namespace detail{
+
+template<typename Hash,typename=void>
+struct hash_is_avalanching_impl:std::false_type{};
+
+template<typename Hash>
+struct hash_is_avalanching_impl<Hash,void_t<typename Hash::is_avalanching>>:
+  std::true_type{};
+
+} /* namespace detail */
+
+/* Each trait can be partially specialized by users for concrete hash functions
+ * when actual characterization differs from default.
+ */
+
+/* Derived from std::true_type if the type Hash::is_avalanching is present,
+ * derived from std::false_type otherwise.
+ */
+template<typename Hash>
+struct hash_is_avalanching:detail::hash_is_avalanching_impl<Hash>::type{};
+
+} /* namespace unordered */
+} /* namespace boost */
+
+#endif

include/boost/unordered/unordered_flat_map.hpp

@@ -0,0 +1,619 @@
+// Copyright (C) 2022 Christian Mazakas
+// 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)
+
+#ifndef BOOST_UNORDERED_UNORDERED_FLAT_MAP_HPP_INCLUDED
+#define BOOST_UNORDERED_UNORDERED_FLAT_MAP_HPP_INCLUDED
+
+#include <boost/config.hpp>
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+#include <boost/unordered/detail/foa.hpp>
+#include <boost/unordered/detail/type_traits.hpp>
+#include <boost/unordered/unordered_flat_map_fwd.hpp>
+
+#include <boost/core/allocator_access.hpp>
+#include <boost/functional/hash.hpp>
+#include <boost/throw_exception.hpp>
+
+#include <initializer_list>
+#include <iterator>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+
+namespace boost {
+  namespace unordered {
+
+#if defined(BOOST_MSVC)
+#pragma warning(push)
+#pragma warning(disable : 4714) /* marked as __forceinline not inlined */
+#endif
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    class unordered_flat_map
+    {
+      struct map_types
+      {
+        using key_type = Key;
+        using raw_key_type = typename std::remove_const<Key>::type;
+        using raw_mapped_type = typename std::remove_const<T>::type;
+
+        using init_type = std::pair<raw_key_type, raw_mapped_type>;
+        using moved_type = std::pair<raw_key_type&&, raw_mapped_type&&>;
+        using value_type = std::pair<Key const, T>;
+
+        template <class K, class V>
+        static raw_key_type const& extract(std::pair<K, V> const& kv)
+        {
+          return kv.first;
+        }
+
+        static moved_type move(value_type& x)
+        {
+          // TODO: we probably need to launder here
+          return {std::move(const_cast<raw_key_type&>(x.first)),
+            std::move(const_cast<raw_mapped_type&>(x.second))};
+        }
+      };
+
+      using table_type = detail::foa::table<map_types, Hash, KeyEqual,
+        typename boost::allocator_rebind<Allocator,
+          typename map_types::value_type>::type>;
+
+      table_type table_;
+
+      template <class K, class V, class H, class KE, class A, class Pred>
+      typename unordered_flat_map<K, V, H, KE, A>::size_type friend erase_if(
+        unordered_flat_map<K, V, H, KE, A>& set, Pred pred);
+
+    public:
+      using key_type = Key;
+      using mapped_type = T;
+      using value_type = typename map_types::value_type;
+      using init_type = typename map_types::init_type;
+      using size_type = std::size_t;
+      using difference_type = std::ptrdiff_t;
+      using hasher = Hash;
+      using key_equal = KeyEqual;
+      using allocator_type = Allocator;
+      using reference = value_type&;
+      using const_reference = value_type const&;
+      using pointer = typename boost::allocator_pointer<allocator_type>::type;
+      using const_pointer =
+        typename boost::allocator_const_pointer<allocator_type>::type;
+      using iterator = typename table_type::iterator;
+      using const_iterator = typename table_type::const_iterator;
+
+      unordered_flat_map() : unordered_flat_map(0) {}
+
+      explicit unordered_flat_map(size_type n, hasher const& h = hasher(),
+        key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : table_(n, h, pred, a)
+      {
+      }
+
+      unordered_flat_map(size_type n, allocator_type const& a)
+          : unordered_flat_map(n, hasher(), key_equal(), a)
+      {
+      }
+
+      unordered_flat_map(size_type n, hasher const& h, allocator_type const& a)
+          : unordered_flat_map(n, h, key_equal(), a)
+      {
+      }
+
+      explicit unordered_flat_map(allocator_type const& a)
+          : unordered_flat_map(0, a)
+      {
+      }
+
+      template <class Iterator>
+      unordered_flat_map(Iterator first, Iterator last, size_type n = 0,
+        hasher const& h = hasher(), key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : unordered_flat_map(n, h, pred, a)
+      {
+        this->insert(first, last);
+      }
+
+      template <class Iterator>
+      unordered_flat_map(
+        Iterator first, Iterator last, size_type n, allocator_type const& a)
+          : unordered_flat_map(first, last, n, hasher(), key_equal(), a)
+      {
+      }
+
+      template <class Iterator>
+      unordered_flat_map(Iterator first, Iterator last, size_type n,
+        hasher const& h, allocator_type const& a)
+          : unordered_flat_map(first, last, n, h, key_equal(), a)
+      {
+      }
+
+      unordered_flat_map(unordered_flat_map const& other) : table_(other.table_)
+      {
+      }
+
+      unordered_flat_map(
+        unordered_flat_map const& other, allocator_type const& a)
+          : table_(other.table_, a)
+      {
+      }
+
+      unordered_flat_map(unordered_flat_map&& other)
+        noexcept(std::is_nothrow_move_constructible<hasher>::value&&
+            std::is_nothrow_move_constructible<key_equal>::value&&
+              std::is_nothrow_move_constructible<allocator_type>::value)
+          : table_(std::move(other.table_))
+      {
+      }
+
+      unordered_flat_map(unordered_flat_map&& other, allocator_type const& al)
+          : table_(std::move(other.table_), al)
+      {
+      }
+
+      unordered_flat_map(std::initializer_list<value_type> ilist,
+        size_type n = 0, hasher const& h = hasher(),
+        key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : unordered_flat_map(ilist.begin(), ilist.end(), n, h, pred, a)
+      {
+      }
+
+      unordered_flat_map(std::initializer_list<value_type> init, size_type n,
+        allocator_type const& a)
+          : unordered_flat_map(init, n, hasher(), key_equal(), a)
+      {
+      }
+
+      unordered_flat_map(std::initializer_list<value_type> init, size_type n,
+        hasher const& h, allocator_type const& a)
+          : unordered_flat_map(init, n, h, key_equal(), a)
+      {
+      }
+
+      ~unordered_flat_map() = default;
+
+      unordered_flat_map& operator=(unordered_flat_map const& other)
+      {
+        table_ = other.table_;
+        return *this;
+      }
+
+      unordered_flat_map& operator=(unordered_flat_map&& other) noexcept(
+        noexcept(std::declval<table_type&>() = std::declval<table_type&&>()))
+      {
+        table_ = std::move(other.table_);
+        return *this;
+      }
+
+      allocator_type get_allocator() const noexcept
+      {
+        return table_.get_allocator();
+      }
+
+      /// Iterators
+      ///
+
+      iterator begin() noexcept { return table_.begin(); }
+      const_iterator begin() const noexcept { return table_.begin(); }
+      const_iterator cbegin() const noexcept { return table_.cbegin(); }
+
+      iterator end() noexcept { return table_.end(); }
+      const_iterator end() const noexcept { return table_.end(); }
+      const_iterator cend() const noexcept { return table_.cend(); }
+
+      /// Capacity
+      ///
+
+      BOOST_ATTRIBUTE_NODISCARD bool empty() const noexcept
+      {
+        return table_.empty();
+      }
+
+      size_type size() const noexcept { return table_.size(); }
+
+      size_type max_size() const noexcept { return table_.max_size(); }
+
+      /// Modifiers
+      ///
+
+      void clear() noexcept { table_.clear(); }
+
+      template <class Ty>
+      BOOST_FORCEINLINE auto insert(Ty&& value)
+        -> decltype(table_.insert(std::forward<Ty>(value)))
+      {
+        return table_.insert(std::forward<Ty>(value));
+      }
+
+      BOOST_FORCEINLINE std::pair<iterator, bool> insert(init_type&& value)
+      {
+        return table_.insert(std::move(value));
+      }
+
+      template <class Ty>
+      BOOST_FORCEINLINE auto insert(const_iterator, Ty&& value)
+        -> decltype(table_.insert(std::forward<Ty>(value)).first)
+      {
+        return table_.insert(std::forward<Ty>(value)).first;
+      }
+
+      BOOST_FORCEINLINE iterator insert(const_iterator, init_type&& value)
+      {
+        return table_.insert(std::move(value)).first;
+      }
+
+      template <class InputIterator>
+      BOOST_FORCEINLINE void insert(InputIterator first, InputIterator last)
+      {
+        for (auto pos = first; pos != last; ++pos) {
+          table_.emplace(*pos);
+        }
+      }
+
+      void insert(std::initializer_list<value_type> ilist)
+      {
+        this->insert(ilist.begin(), ilist.end());
+      }
+
+      template <class M>
+      std::pair<iterator, bool> insert_or_assign(key_type const& key, M&& obj)
+      {
+        auto iter_bool_pair = table_.try_emplace(key, std::forward<M>(obj));
+        if (iter_bool_pair.second) {
+          return iter_bool_pair;
+        }
+        iter_bool_pair.first->second = std::forward<M>(obj);
+        return iter_bool_pair;
+      }
+
+      template <class M>
+      std::pair<iterator, bool> insert_or_assign(key_type&& key, M&& obj)
+      {
+        auto iter_bool_pair =
+          table_.try_emplace(std::move(key), std::forward<M>(obj));
+        if (iter_bool_pair.second) {
+          return iter_bool_pair;
+        }
+        iter_bool_pair.first->second = std::forward<M>(obj);
+        return iter_bool_pair;
+      }
+
+      template <class M>
+      iterator insert_or_assign(const_iterator, key_type const& key, M&& obj)
+      {
+        return this->insert_or_assign(key, std::forward<M>(obj)).first;
+      }
+
+      template <class M>
+      iterator insert_or_assign(const_iterator, key_type&& key, M&& obj)
+      {
+        return this->insert_or_assign(std::move(key), std::forward<M>(obj))
+          .first;
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE std::pair<iterator, bool> emplace(Args&&... args)
+      {
+        return table_.emplace(std::forward<Args>(args)...);
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE iterator emplace_hint(const_iterator, Args&&... args)
+      {
+        return table_.emplace(std::forward<Args>(args)...).first;
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE std::pair<iterator, bool> try_emplace(
+        key_type const& key, Args&&... args)
+      {
+        return table_.try_emplace(key, std::forward<Args>(args)...);
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE std::pair<iterator, bool> try_emplace(
+        key_type&& key, Args&&... args)
+      {
+        return table_.try_emplace(std::move(key), std::forward<Args>(args)...);
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE iterator try_emplace(
+        const_iterator, key_type const& key, Args&&... args)
+      {
+        return table_.try_emplace(key, std::forward<Args>(args)...).first;
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE iterator try_emplace(
+        const_iterator, key_type&& key, Args&&... args)
+      {
+        return table_.try_emplace(std::move(key), std::forward<Args>(args)...)
+          .first;
+      }
+
+      BOOST_FORCEINLINE void erase(iterator pos) { table_.erase(pos); }
+      BOOST_FORCEINLINE void erase(const_iterator pos)
+      {
+        return table_.erase(pos);
+      }
+      iterator erase(const_iterator first, const_iterator last)
+      {
+        while (first != last) {
+          this->erase(first++);
+        }
+        return iterator{detail::foa::const_iterator_cast_tag{}, last};
+      }
+
+      BOOST_FORCEINLINE size_type erase(key_type const& key)
+      {
+        return table_.erase(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        detail::transparent_non_iterable<K, unordered_flat_map>::value,
+        size_type>::type
+      erase(K const& key)
+      {
+        return table_.erase(key);
+      }
+
+      void swap(unordered_flat_map& rhs) noexcept(
+        noexcept(std::declval<table_type&>().swap(std::declval<table_type&>())))
+      {
+        table_.swap(rhs.table_);
+      }
+
+      template <class H2, class P2>
+      void merge(
+        unordered_flat_map<key_type, mapped_type, H2, P2, allocator_type>&
+          source)
+      {
+        table_.merge(source.table_);
+      }
+
+      template <class H2, class P2>
+      void merge(
+        unordered_flat_map<key_type, mapped_type, H2, P2, allocator_type>&&
+          source)
+      {
+        table_.merge(std::move(source.table_));
+      }
+
+      /// Lookup
+      ///
+
+      mapped_type& at(key_type const& key)
+      {
+        auto pos = table_.find(key);
+        if (pos != table_.end()) {
+          return pos->second;
+        }
+        // TODO: someday refactor this to conditionally serialize the key and
+        // include it in the error message
+        //
+        boost::throw_exception(
+          std::out_of_range("key was not found in unordered_flat_map"));
+      }
+
+      mapped_type const& at(key_type const& key) const
+      {
+        auto pos = table_.find(key);
+        if (pos != table_.end()) {
+          return pos->second;
+        }
+        boost::throw_exception(
+          std::out_of_range("key was not found in unordered_flat_map"));
+      }
+
+      mapped_type& operator[](key_type const& key)
+      {
+        return table_.try_emplace(key).first->second;
+      }
+
+      mapped_type& operator[](key_type&& key)
+      {
+        return table_.try_emplace(std::move(key)).first->second;
+      }
+
+      size_type count(key_type const& key) const
+      {
+        auto pos = table_.find(key);
+        return pos != table_.end() ? 1 : 0;
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value, size_type>::type
+      count(K const& key) const
+      {
+        auto pos = table_.find(key);
+        return pos != table_.end() ? 1 : 0;
+      }
+
+      BOOST_FORCEINLINE iterator find(key_type const& key)
+      {
+        return table_.find(key);
+      }
+
+      BOOST_FORCEINLINE const_iterator find(key_type const& key) const
+      {
+        return table_.find(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        iterator>::type
+      find(K const& key)
+      {
+        return table_.find(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        const_iterator>::type
+      find(K const& key) const
+      {
+        return table_.find(key);
+      }
+
+      bool contains(key_type const& key) const
+      {
+        return this->find(key) != this->end();
+      }
+
+      template <class K>
+      typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        bool>::type
+      contains(K const& key) const
+      {
+        return this->find(key) != this->end();
+      }
+
+      std::pair<iterator, iterator> equal_range(key_type const& key)
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      std::pair<const_iterator, const_iterator> equal_range(
+        key_type const& key) const
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value,
+        std::pair<iterator, iterator> >::type
+      equal_range(K const& key)
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value,
+        std::pair<const_iterator, const_iterator> >::type
+      equal_range(K const& key) const
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      /// Hash Policy
+      ///
+
+      size_type bucket_count() const noexcept { return table_.capacity(); }
+
+      float load_factor() const noexcept { return table_.load_factor(); }
+
+      float max_load_factor() const noexcept
+      {
+        return table_.max_load_factor();
+      }
+
+      void max_load_factor(float) {}
+
+      void rehash(size_type n) { table_.rehash(n); }
+
+      void reserve(size_type n) { table_.reserve(n); }
+
+      /// Observers
+      ///
+
+      hasher hash_function() const { return table_.hash_function(); }
+
+      key_equal key_eq() const { return table_.key_eq(); }
+    };
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    bool operator==(
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& rhs)
+    {
+      if (&lhs == &rhs) {
+        return true;
+      }
+
+      return (lhs.size() == rhs.size()) && ([&] {
+        for (auto const& kvp : lhs) {
+          auto pos = rhs.find(kvp.first);
+          if ((pos == rhs.end()) || (*pos != kvp)) {
+            return false;
+          }
+        }
+        return true;
+      })();
+    }
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    bool operator!=(
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& rhs)
+    {
+      return !(lhs == rhs);
+    }
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    void swap(unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>& rhs)
+      noexcept(noexcept(lhs.swap(rhs)))
+    {
+      lhs.swap(rhs);
+    }
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator,
+      class Pred>
+    typename unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>::size_type
+    erase_if(
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>& map, Pred pred)
+    {
+      return erase_if(map.table_, pred);
+    }
+
+#if defined(BOOST_MSVC)
+#pragma warning(pop) /* C4714 */
+#endif
+
+  } // namespace unordered
+} // namespace boost
+
+#endif

include/boost/unordered/unordered_flat_map_fwd.hpp

@@ -0,0 +1,49 @@
+
+// Copyright (C) 2022 Christian Mazakas
+// 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)
+
+#ifndef BOOST_UNORDERED_FLAT_MAP_FWD_HPP_INCLUDED
+#define BOOST_UNORDERED_FLAT_MAP_FWD_HPP_INCLUDED
+
+#include <boost/config.hpp>
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+#include <boost/functional/hash_fwd.hpp>
+#include <boost/unordered/detail/fwd.hpp>
+#include <functional>
+#include <memory>
+
+namespace boost {
+  namespace unordered {
+    template <class Key, class T, class Hash = boost::hash<Key>,
+      class KeyEqual = std::equal_to<Key>,
+      class Allocator = std::allocator<std::pair<const Key, T> > >
+    class unordered_flat_map;
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    bool operator==(
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& rhs);
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    bool operator!=(
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator> const& rhs);
+
+    template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+    void swap(unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>& lhs,
+      unordered_flat_map<Key, T, Hash, KeyEqual, Allocator>& rhs)
+      noexcept(noexcept(lhs.swap(rhs)));
+  } // namespace unordered
+
+  using boost::unordered::unordered_flat_map;
+
+  using boost::unordered::swap;
+  using boost::unordered::operator==;
+  using boost::unordered::operator!=;
+} // namespace boost
+
+#endif

include/boost/unordered/unordered_flat_set.hpp

@@ -0,0 +1,494 @@
+// Copyright (C) 2022 Christian Mazakas
+// 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)
+
+#ifndef BOOST_UNORDERED_UNORDERED_FLAT_SET_HPP_INCLUDED
+#define BOOST_UNORDERED_UNORDERED_FLAT_SET_HPP_INCLUDED
+
+#include <boost/config.hpp>
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+#include <boost/unordered/detail/foa.hpp>
+#include <boost/unordered/detail/type_traits.hpp>
+#include <boost/unordered/unordered_flat_set_fwd.hpp>
+
+#include <boost/core/allocator_access.hpp>
+#include <boost/functional/hash.hpp>
+
+#include <initializer_list>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+namespace boost {
+  namespace unordered {
+
+#if defined(BOOST_MSVC)
+#pragma warning(push)
+#pragma warning(disable : 4714) /* marked as __forceinline not inlined */
+#endif
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    class unordered_flat_set
+    {
+      struct set_types
+      {
+        using key_type = Key;
+        using init_type = Key;
+        using value_type = Key;
+        static Key const& extract(value_type const& key) { return key; }
+        static Key&& move(value_type& x) { return std::move(x); }
+      };
+
+      using table_type = detail::foa::table<set_types, Hash, KeyEqual,
+        typename boost::allocator_rebind<Allocator,
+          typename set_types::value_type>::type>;
+
+      table_type table_;
+
+      template <class K, class H, class KE, class A, class Pred>
+      typename unordered_flat_set<K, H, KE, A>::size_type friend erase_if(
+        unordered_flat_set<K, H, KE, A>& set, Pred pred);
+
+    public:
+      using key_type = Key;
+      using value_type = typename set_types::value_type;
+      using init_type = typename set_types::init_type;
+      using size_type = std::size_t;
+      using difference_type = std::ptrdiff_t;
+      using hasher = Hash;
+      using key_equal = KeyEqual;
+      using allocator_type = Allocator;
+      using reference = value_type&;
+      using const_reference = value_type const&;
+      using pointer = typename boost::allocator_pointer<allocator_type>::type;
+      using const_pointer =
+        typename boost::allocator_const_pointer<allocator_type>::type;
+      using iterator = typename table_type::iterator;
+      using const_iterator = typename table_type::const_iterator;
+
+      unordered_flat_set() : unordered_flat_set(0) {}
+
+      explicit unordered_flat_set(size_type n, hasher const& h = hasher(),
+        key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : table_(n, h, pred, a)
+      {
+      }
+
+      unordered_flat_set(size_type n, allocator_type const& a)
+          : unordered_flat_set(n, hasher(), key_equal(), a)
+      {
+      }
+
+      unordered_flat_set(size_type n, hasher const& h, allocator_type const& a)
+          : unordered_flat_set(n, h, key_equal(), a)
+      {
+      }
+
+      explicit unordered_flat_set(allocator_type const& a)
+          : unordered_flat_set(0, a)
+      {
+      }
+
+      template <class Iterator>
+      unordered_flat_set(Iterator first, Iterator last, size_type n = 0,
+        hasher const& h = hasher(), key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : unordered_flat_set(n, h, pred, a)
+      {
+        this->insert(first, last);
+      }
+
+      template <class InputIt>
+      unordered_flat_set(
+        InputIt first, InputIt last, size_type n, allocator_type const& a)
+          : unordered_flat_set(first, last, n, hasher(), key_equal(), a)
+      {
+      }
+
+      template <class Iterator>
+      unordered_flat_set(Iterator first, Iterator last, size_type n,
+        hasher const& h, allocator_type const& a)
+          : unordered_flat_set(first, last, n, h, key_equal(), a)
+      {
+      }
+
+      unordered_flat_set(unordered_flat_set const& other) : table_(other.table_)
+      {
+      }
+
+      unordered_flat_set(
+        unordered_flat_set const& other, allocator_type const& a)
+          : table_(other.table_, a)
+      {
+      }
+
+      unordered_flat_set(unordered_flat_set&& other)
+        noexcept(std::is_nothrow_move_constructible<hasher>::value&&
+            std::is_nothrow_move_constructible<key_equal>::value&&
+              std::is_nothrow_move_constructible<allocator_type>::value)
+          : table_(std::move(other.table_))
+      {
+      }
+
+      unordered_flat_set(unordered_flat_set&& other, allocator_type const& al)
+          : table_(std::move(other.table_), al)
+      {
+      }
+
+      unordered_flat_set(std::initializer_list<value_type> ilist,
+        size_type n = 0, hasher const& h = hasher(),
+        key_equal const& pred = key_equal(),
+        allocator_type const& a = allocator_type())
+          : unordered_flat_set(ilist.begin(), ilist.end(), n, h, pred, a)
+      {
+      }
+
+      unordered_flat_set(std::initializer_list<value_type> init, size_type n,
+        allocator_type const& a)
+          : unordered_flat_set(init, n, hasher(), key_equal(), a)
+      {
+      }
+
+      unordered_flat_set(std::initializer_list<value_type> init, size_type n,
+        hasher const& h, allocator_type const& a)
+          : unordered_flat_set(init, n, h, key_equal(), a)
+      {
+      }
+
+      ~unordered_flat_set() = default;
+
+      unordered_flat_set& operator=(unordered_flat_set const& other)
+      {
+        table_ = other.table_;
+        return *this;
+      }
+
+      unordered_flat_set& operator=(unordered_flat_set&& other) noexcept(
+        noexcept(std::declval<table_type&>() = std::declval<table_type&&>()))
+      {
+        table_ = std::move(other.table_);
+        return *this;
+      }
+
+      allocator_type get_allocator() const noexcept
+      {
+        return table_.get_allocator();
+      }
+
+      /// Iterators
+      ///
+
+      iterator begin() noexcept { return table_.begin(); }
+      const_iterator begin() const noexcept { return table_.begin(); }
+      const_iterator cbegin() const noexcept { return table_.cbegin(); }
+
+      iterator end() noexcept { return table_.end(); }
+      const_iterator end() const noexcept { return table_.end(); }
+      const_iterator cend() const noexcept { return table_.cend(); }
+
+      /// Capacity
+      ///
+
+      BOOST_ATTRIBUTE_NODISCARD bool empty() const noexcept
+      {
+        return table_.empty();
+      }
+
+      size_type size() const noexcept { return table_.size(); }
+
+      size_type max_size() const noexcept { return table_.max_size(); }
+
+      /// Modifiers
+      ///
+
+      void clear() noexcept { table_.clear(); }
+
+      BOOST_FORCEINLINE std::pair<iterator, bool> insert(
+        value_type const& value)
+      {
+        return table_.insert(value);
+      }
+
+      BOOST_FORCEINLINE std::pair<iterator, bool> insert(value_type&& value)
+      {
+        return table_.insert(std::move(value));
+      }
+
+      BOOST_FORCEINLINE iterator insert(const_iterator, value_type const& value)
+      {
+        return table_.insert(value).first;
+      }
+
+      BOOST_FORCEINLINE iterator insert(const_iterator, value_type&& value)
+      {
+        return table_.insert(std::move(value)).first;
+      }
+
+      template <class InputIterator>
+      void insert(InputIterator first, InputIterator last)
+      {
+        for (auto pos = first; pos != last; ++pos) {
+          table_.emplace(*pos);
+        }
+      }
+
+      void insert(std::initializer_list<value_type> ilist)
+      {
+        this->insert(ilist.begin(), ilist.end());
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE std::pair<iterator, bool> emplace(Args&&... args)
+      {
+        return table_.emplace(std::forward<Args>(args)...);
+      }
+
+      template <class... Args>
+      BOOST_FORCEINLINE iterator emplace_hint(const_iterator, Args&&... args)
+      {
+        return table_.emplace(std::forward<Args>(args)...).first;
+      }
+
+      BOOST_FORCEINLINE void erase(const_iterator pos)
+      {
+        return table_.erase(pos);
+      }
+      iterator erase(const_iterator first, const_iterator last)
+      {
+        while (first != last) {
+          this->erase(first++);
+        }
+        return iterator{detail::foa::const_iterator_cast_tag{}, last};
+      }
+
+      BOOST_FORCEINLINE size_type erase(key_type const& key)
+      {
+        return table_.erase(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        detail::transparent_non_iterable<K, unordered_flat_set>::value,
+        size_type>::type
+      erase(K const& key)
+      {
+        return table_.erase(key);
+      }
+
+      void swap(unordered_flat_set& rhs) noexcept(
+        noexcept(std::declval<table_type&>().swap(std::declval<table_type&>())))
+      {
+        table_.swap(rhs.table_);
+      }
+
+      template <class H2, class P2>
+      void merge(unordered_flat_set<key_type, H2, P2, allocator_type>& source)
+      {
+        table_.merge(source.table_);
+      }
+
+      template <class H2, class P2>
+      void merge(unordered_flat_set<key_type, H2, P2, allocator_type>&& source)
+      {
+        table_.merge(std::move(source.table_));
+      }
+
+      /// Lookup
+      ///
+
+      size_type count(key_type const& key) const
+      {
+        auto pos = table_.find(key);
+        return pos != table_.end() ? 1 : 0;
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value, size_type>::type
+      count(K const& key) const
+      {
+        auto pos = table_.find(key);
+        return pos != table_.end() ? 1 : 0;
+      }
+
+      BOOST_FORCEINLINE iterator find(key_type const& key)
+      {
+        return table_.find(key);
+      }
+
+      BOOST_FORCEINLINE const_iterator find(key_type const& key) const
+      {
+        return table_.find(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        iterator>::type
+      find(K const& key)
+      {
+        return table_.find(key);
+      }
+
+      template <class K>
+      BOOST_FORCEINLINE typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        const_iterator>::type
+      find(K const& key) const
+      {
+        return table_.find(key);
+      }
+
+      bool contains(key_type const& key) const
+      {
+        return this->find(key) != this->end();
+      }
+
+      template <class K>
+      typename std::enable_if<
+        boost::unordered::detail::are_transparent<K, hasher, key_equal>::value,
+        bool>::type
+      contains(K const& key) const
+      {
+        return this->find(key) != this->end();
+      }
+
+      std::pair<iterator, iterator> equal_range(key_type const& key)
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      std::pair<const_iterator, const_iterator> equal_range(
+        key_type const& key) const
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value,
+        std::pair<iterator, iterator> >::type
+      equal_range(K const& key)
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      template <class K>
+      typename std::enable_if<
+        detail::are_transparent<K, hasher, key_equal>::value,
+        std::pair<const_iterator, const_iterator> >::type
+      equal_range(K const& key) const
+      {
+        auto pos = table_.find(key);
+        if (pos == table_.end()) {
+          return {pos, pos};
+        }
+
+        auto next = pos;
+        ++next;
+        return {pos, next};
+      }
+
+      /// Hash Policy
+      ///
+
+      size_type bucket_count() const noexcept { return table_.capacity(); }
+
+      float load_factor() const noexcept { return table_.load_factor(); }
+
+      float max_load_factor() const noexcept
+      {
+        return table_.max_load_factor();
+      }
+
+      void max_load_factor(float) {}
+
+      void rehash(size_type n) { table_.rehash(n); }
+
+      void reserve(size_type n) { table_.reserve(n); }
+
+      /// Observers
+      ///
+
+      hasher hash_function() const { return table_.hash_function(); }
+
+      key_equal key_eq() const { return table_.key_eq(); }
+    };
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    bool operator==(
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& rhs)
+    {
+      if (&lhs == &rhs) {
+        return true;
+      }
+
+      return (lhs.size() == rhs.size()) && ([&] {
+        for (auto const& key : lhs) {
+          auto pos = rhs.find(key);
+          if ((pos == rhs.end()) || (key != *pos)) {
+            return false;
+          }
+        }
+        return true;
+      })();
+    }
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    bool operator!=(
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& rhs)
+    {
+      return !(lhs == rhs);
+    }
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    void swap(unordered_flat_set<Key, Hash, KeyEqual, Allocator>& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator>& rhs)
+      noexcept(noexcept(lhs.swap(rhs)))
+    {
+      lhs.swap(rhs);
+    }
+
+    template <class Key, class Hash, class KeyEqual, class Allocator,
+      class Pred>
+    typename unordered_flat_set<Key, Hash, KeyEqual, Allocator>::size_type
+    erase_if(unordered_flat_set<Key, Hash, KeyEqual, Allocator>& set, Pred pred)
+    {
+      return erase_if(set.table_, pred);
+    }
+
+#if defined(BOOST_MSVC)
+#pragma warning(pop) /* C4714 */
+#endif
+
+  } // namespace unordered
+} // namespace boost
+
+#endif

include/boost/unordered/unordered_flat_set_fwd.hpp

@@ -0,0 +1,49 @@
+
+// Copyright (C) 2022 Christian Mazakas
+// 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)
+
+#ifndef BOOST_UNORDERED_FLAT_SET_FWD_HPP_INCLUDED
+#define BOOST_UNORDERED_FLAT_SET_FWD_HPP_INCLUDED
+
+#include <boost/config.hpp>
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+#include <boost/functional/hash_fwd.hpp>
+#include <boost/unordered/detail/fwd.hpp>
+#include <functional>
+#include <memory>
+
+namespace boost {
+  namespace unordered {
+    template <class Key, class Hash = boost::hash<Key>,
+      class KeyEqual = std::equal_to<Key>,
+      class Allocator = std::allocator<Key> >
+    class unordered_flat_set;
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    bool operator==(
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& rhs);
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    bool operator!=(
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator> const& rhs);
+
+    template <class Key, class Hash, class KeyEqual, class Allocator>
+    void swap(unordered_flat_set<Key, Hash, KeyEqual, Allocator>& lhs,
+      unordered_flat_set<Key, Hash, KeyEqual, Allocator>& rhs)
+      noexcept(noexcept(lhs.swap(rhs)));
+  } // namespace unordered
+
+  using boost::unordered::unordered_flat_set;
+
+  using boost::unordered::swap;
+  using boost::unordered::operator==;
+  using boost::unordered::operator!=;
+} // namespace boost
+
+#endif

include/boost/unordered/unordered_map.hpp

@@ -1664,8 +1664,6 @@ namespace boost {
 
     template <class K, class T, class H, class P, class A>
     unordered_map<K, T, H, P, A>::unordered_map()
-        : table_(boost::unordered::detail::default_bucket_count, hasher(),
-            key_equal(), allocator_type())
     {
     }
 
@@ -2069,6 +2067,10 @@ namespace boost {
     template <class K, class T, class H, class P, class A>
     float unordered_map<K, T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());
@@ -2143,8 +2145,6 @@ namespace boost {
 
     template <class K, class T, class H, class P, class A>
     unordered_multimap<K, T, H, P, A>::unordered_multimap()
-        : table_(boost::unordered::detail::default_bucket_count, hasher(),
-            key_equal(), allocator_type())
     {
     }
 
@@ -2506,6 +2506,10 @@ namespace boost {
     template <class K, class T, class H, class P, class A>
     float unordered_multimap<K, T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());

include/boost/unordered/unordered_set.hpp

@@ -1266,8 +1266,6 @@ namespace boost {
     ////////////////////////////////////////////////////////////////////////////
     template <class T, class H, class P, class A>
     unordered_set<T, H, P, A>::unordered_set()
-        : table_(boost::unordered::detail::default_bucket_count, hasher(),
-            key_equal(), allocator_type())
     {
     }
 
@@ -1586,6 +1584,10 @@ namespace boost {
     template <class T, class H, class P, class A>
     float unordered_set<T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());
@@ -1660,8 +1662,6 @@ namespace boost {
 
     template <class T, class H, class P, class A>
     unordered_multiset<T, H, P, A>::unordered_multiset()
-        : table_(boost::unordered::detail::default_bucket_count, hasher(),
-            key_equal(), allocator_type())
     {
     }
 
@@ -1986,6 +1986,10 @@ namespace boost {
     template <class T, class H, class P, class A>
     float unordered_multiset<T, H, P, A>::load_factor() const BOOST_NOEXCEPT
     {
+      if (table_.size_ == 0) {
+        return 0.0f;
+      }
+
       BOOST_ASSERT(table_.bucket_count() != 0);
       return static_cast<float>(table_.size_) /
              static_cast<float>(table_.bucket_count());

test/Jamfile.v2

@@ -47,6 +47,7 @@ run unordered/equivalent_keys_tests.cpp ;
 run unordered/constructor_tests.cpp ;
 run unordered/copy_tests.cpp ;
 run unordered/move_tests.cpp ;
+run unordered/post_move_tests.cpp ;
 run unordered/assign_tests.cpp ;
 run unordered/insert_tests.cpp ;
 run unordered/insert_stable_tests.cpp ;
@@ -95,3 +96,55 @@ run exception/swap_exception_tests.cpp : : : <define>BOOST_UNORDERED_SWAP_METHOD
 run exception/merge_exception_tests.cpp ;
 
 run quick.cpp ;
+
+import ../../config/checks/config : requires ;
+
+CPP11 = [ requires cxx11_constexpr cxx11_noexcept cxx11_decltype cxx11_alignas ] ;
+
+rule build_foa ( name )
+{
+  run unordered/$(name).cpp : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_$(name) ;
+}
+
+build_foa fwd_set_test ;
+build_foa fwd_map_test ;
+build_foa compile_set ;
+build_foa compile_map ;
+build_foa noexcept_tests ;
+run unordered/link_test_1.cpp unordered/link_test_2.cpp : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_link_test ;
+build_foa incomplete_test ;
+build_foa simple_tests ;
+build_foa equivalent_keys_tests ;
+build_foa constructor_tests ;
+build_foa copy_tests ;
+build_foa move_tests ;
+build_foa post_move_tests ;
+build_foa assign_tests ;
+build_foa insert_tests ;
+build_foa insert_hint_tests ;
+build_foa emplace_tests ;
+build_foa erase_tests ;
+build_foa merge_tests ;
+build_foa find_tests ;
+build_foa at_tests ;
+build_foa load_factor_tests ;
+build_foa rehash_tests ;
+build_foa equality_tests ;
+build_foa swap_tests ;
+run unordered/scoped_allocator.cpp : : : $(CPP11) <toolset>msvc-14.0:<build>no <define>BOOST_UNORDERED_FOA_TESTS : foa_scoped_allocator ;
+build_foa transparent_tests ;
+build_foa reserve_tests ;
+build_foa contains_tests ;
+build_foa erase_if ;
+build_foa scary_tests ;
+build_foa init_type_insert_tests ;
+
+run exception/constructor_exception_tests.cpp : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_constructor_exception_tests ;
+run exception/copy_exception_tests.cpp        : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_copy_exception_tests ;
+run exception/assign_exception_tests.cpp      : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_assign_exception_tests ;
+run exception/move_assign_exception_tests.cpp : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_move_assign_exception_tests ;
+run exception/insert_exception_tests.cpp      : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_insert_exception_tests ;
+run exception/erase_exception_tests.cpp       : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_erase_exception_tests ;
+run exception/rehash_exception_tests.cpp      : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_rehash_exception_tests ;
+run exception/swap_exception_tests.cpp        : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_swap_exception_tests ;
+run exception/merge_exception_tests.cpp       : : : $(CPP11) <define>BOOST_UNORDERED_FOA_TESTS : foa_merge_exception_tests ;

test/exception/containers.hpp

@@ -1,17 +1,33 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_map.hpp>
-#include <boost/unordered_set.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../objects/exception.hpp"
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_set<test::exception::object,
+  test::exception::hash, test::exception::equal_to,
+  test::exception::allocator<test::exception::object> >
+  test_set;
+
+typedef boost::unordered_flat_map<test::exception::object,
+  test::exception::object, test::exception::hash, test::exception::equal_to,
+  test::exception::allocator2<test::exception::object> >
+  test_map;
+
+typedef boost::unordered_flat_set<
+  std::pair<test::exception::object, test::exception::object>,
+  test::exception::hash, test::exception::equal_to,
+  test::exception::allocator<test::exception::object> >
+  test_pair_set;
+
+#define CONTAINER_SEQ (test_set)(test_map)
+#define CONTAINER_PAIR_SEQ (test_pair_set)(test_map)
+#else
 typedef boost::unordered_set<test::exception::object, test::exception::hash,
   test::exception::equal_to,
   test::exception::allocator<test::exception::object> >
@@ -42,3 +58,5 @@ typedef boost::unordered_multiset<
 #define CONTAINER_SEQ (test_set)(test_multiset)(test_map)(test_multimap)
 #define CONTAINER_PAIR_SEQ                                                     \
   (test_pair_set)(test_pair_multiset)(test_map)(test_multimap)
+
+#endif

test/exception/insert_exception_tests.cpp

@@ -1,5 +1,6 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 #include "./containers.hpp"
@@ -95,7 +96,7 @@ void insert_rehash_exception_test(
   T*, Inserter insert, test::random_generator gen)
 {
   for (int i = 0; i < 5; ++i) {
-    T x;
+    T x(1);
     rehash_prep(x);
 
     test::random_values<T> v2(5, gen);
@@ -221,16 +222,41 @@ struct emplace_lvalue_pos_type
 } emplace_lvalue_pos;
 
 // Run the exception tests in various combinations.
+using test::default_generator;
+using test::limited_range;
+using test::generate_collisions;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+test_set* test_set_;
+test_map* test_map_;
+
+// clang-format off
+UNORDERED_TEST(insert_exception_test,
+    ((test_set_)(test_map_))
+    ((insert_lvalue)(insert_lvalue_begin)(insert_lvalue_end)
+     (insert_lvalue_pos)(insert_single_item_range)
+     (emplace_lvalue)(emplace_lvalue_begin)(emplace_lvalue_end)
+     (emplace_lvalue_pos)
+    )
+    ((default_generator)(limited_range)(generate_collisions))
+)
+
+UNORDERED_TEST(insert_rehash_exception_test,
+    ((test_set_)(test_map_))
+    ((insert_lvalue)(insert_lvalue_begin)(insert_lvalue_end)
+     (insert_lvalue_pos)(insert_single_item_range)
+     (emplace_lvalue)(emplace_lvalue_begin)(emplace_lvalue_end)
+     (emplace_lvalue_pos)
+    )
+    ((default_generator)(limited_range)(generate_collisions))
+)
+// clang-format on
+#else
 test_set* test_set_;
 test_multiset* test_multiset_;
 test_map* test_map_;
 test_multimap* test_multimap_;
 
-using test::default_generator;
-using test::limited_range;
-using test::generate_collisions;
-
 // clang-format off
 UNORDERED_TEST(insert_exception_test,
     ((test_set_)(test_multiset_)(test_map_)(test_multimap_))
@@ -252,6 +278,7 @@ UNORDERED_TEST(insert_rehash_exception_test,
     ((default_generator)(limited_range)(generate_collisions))
 )
 // clang-format on
+#endif
 
 // Repeat insert tests with pairs
 
@@ -259,8 +286,13 @@ struct pair_emplace_type : inserter_base
 {
   template <typename T, typename Iterator> void operator()(T& x, Iterator it)
   {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    x.emplace(std::piecewise_construct, std::make_tuple(it->first),
+      std::make_tuple(it->second));
+#else
     x.emplace(boost::unordered::piecewise_construct,
       boost::make_tuple(it->first), boost::make_tuple(it->second));
+#endif
   }
 } pair_emplace;
 
@@ -268,12 +300,34 @@ struct pair_emplace2_type : inserter_base
 {
   template <typename T, typename Iterator> void operator()(T& x, Iterator it)
   {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    x.emplace_hint(x.begin(), std::piecewise_construct,
+      std::make_tuple(it->first),
+      std::make_tuple(it->second.tag1_, it->second.tag2_));
+#else
     x.emplace_hint(x.begin(), boost::unordered::piecewise_construct,
       boost::make_tuple(it->first),
       boost::make_tuple(it->second.tag1_, it->second.tag2_));
+#endif
   }
 } pair_emplace2;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+test_pair_set* test_pair_set_;
+
+// clang-format off
+UNORDERED_TEST(insert_exception_test,
+    ((test_pair_set_)(test_map_))
+    ((pair_emplace)(pair_emplace2))
+    ((default_generator)(limited_range)(generate_collisions))
+)
+UNORDERED_TEST(insert_rehash_exception_test,
+    ((test_pair_set_)(test_map_))
+    ((pair_emplace)(pair_emplace2))
+    ((default_generator)(limited_range)(generate_collisions))
+)
+// clang-format on
+#else
 test_pair_set* test_pair_set_;
 test_pair_multiset* test_pair_multiset_;
 
@@ -289,6 +343,7 @@ UNORDERED_TEST(insert_rehash_exception_test,
     ((default_generator)(limited_range)(generate_collisions))
 )
 // clang-format on
+#endif
 
 // Test inserting using operator[]
 
@@ -393,7 +448,7 @@ template <typename T>
 void insert_range_rehash_exception_test(T*, test::random_generator gen)
 {
   for (int i = 0; i < 5; ++i) {
-    T x;
+    T x(1);
     rehash_prep(x);
 
     test::random_values<T> v2(5, gen);
@@ -401,6 +456,19 @@ void insert_range_rehash_exception_test(T*, test::random_generator gen)
   }
 }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+// clang-format off
+UNORDERED_TEST(insert_range_exception_test,
+    ((test_set_)(test_map_))
+    ((default_generator)(limited_range)(generate_collisions))
+)
+
+UNORDERED_TEST(insert_range_rehash_exception_test,
+    ((test_set_)(test_map_))
+    ((default_generator)(limited_range)(generate_collisions))
+)
+// clang-format on
+#else
 // clang-format off
 UNORDERED_TEST(insert_range_exception_test,
     ((test_set_)(test_multiset_)(test_map_)(test_multimap_))
@@ -412,5 +480,6 @@ UNORDERED_TEST(insert_range_rehash_exception_test,
     ((default_generator)(limited_range)(generate_collisions))
 )
 // clang-format on
+#endif
 
 RUN_TESTS()

test/exception/merge_exception_tests.cpp

@@ -1,5 +1,6 @@
 
 // Copyright 2017-2018 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
@@ -52,6 +53,53 @@ void merge_exception_test(T1 const*, T2 const*, std::size_t count12, int tag12,
   EXCEPTION_LOOP(merge_exception_test(x, y))
 }
 
+using test::default_generator;
+using test::generate_collisions;
+using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+boost::unordered_flat_set<test::exception::object, test::exception::hash,
+  test::exception::equal_to,
+  test::exception::allocator<test::exception::object> >* test_set_;
+boost::unordered_flat_map<test::exception::object, test::exception::object,
+  test::exception::hash, test::exception::equal_to,
+  test::exception::allocator2<test::exception::object> >* test_map_;
+
+// clang-format off
+UNORDERED_MULTI_TEST(set_merge, merge_exception_test,
+    ((test_set_))
+    ((test_set_))
+    ((0x0000)(0x6400)(0x0064)(0x0a64)(0x3232))
+    ((0x0000)(0x0001)(0x0102))
+    ((default_generator)(limited_range))
+    ((default_generator)(limited_range))
+)
+UNORDERED_MULTI_TEST(map_merge, merge_exception_test,
+    ((test_map_))
+    ((test_map_))
+    ((0x0000)(0x6400)(0x0064)(0x0a64)(0x3232))
+    ((0x0101)(0x0200)(0x0201))
+    ((default_generator)(limited_range))
+    ((default_generator)(limited_range))
+)
+// Run fewer generate_collisions tests, as they're slow.
+UNORDERED_MULTI_TEST(set_merge_collisions, merge_exception_test,
+    ((test_set_))
+    ((test_set_))
+    ((0x0a0a))
+    ((0x0202)(0x0100)(0x0201))
+    ((generate_collisions))
+    ((generate_collisions))
+)
+UNORDERED_MULTI_TEST(map_merge_collisions, merge_exception_test,
+    ((test_map_))
+    ((test_map_))
+    ((0x0a0a))
+    ((0x0000)(0x0002)(0x0102))
+    ((generate_collisions))
+    ((generate_collisions))
+)
+#else
 boost::unordered_set<test::exception::object, test::exception::hash,
   test::exception::equal_to,
   test::exception::allocator<test::exception::object> >* test_set_;
@@ -65,10 +113,6 @@ boost::unordered_multimap<test::exception::object, test::exception::object,
   test::exception::hash, test::exception::equal_to,
   test::exception::allocator2<test::exception::object> >* test_multimap_;
 
-using test::default_generator;
-using test::generate_collisions;
-using test::limited_range;
-
 // clang-format off
 UNORDERED_MULTI_TEST(set_merge, merge_exception_test,
     ((test_set_)(test_multiset_))
@@ -104,5 +148,6 @@ UNORDERED_MULTI_TEST(map_merge_collisions, merge_exception_test,
     ((generate_collisions))
 )
 // clang-format on
+#endif
 
 RUN_TESTS_QUIET()

test/exception/swap_exception_tests.cpp

@@ -1,10 +1,15 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 #include "./containers.hpp"
 
+#if defined(BOOST_UNORDERED_FOA_TESTS)
+#define BOOST_UNORDERED_FOA_WEAK_GUARANTEE_SWAP_EXCEPTIONS_TESTS
+#endif
+
 #include "../helpers/invariants.hpp"
 #include "../helpers/random_values.hpp"
 #include "../helpers/tracker.hpp"

test/helpers/invariants.hpp

@@ -1,5 +1,6 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
@@ -53,11 +54,22 @@ namespace test {
       if (test::has_unique_keys<X>::value && count != 1)
         BOOST_ERROR("Non-unique key.");
 
+#if !defined(BOOST_UNORDERED_FOA_WEAK_GUARANTEE_SWAP_EXCEPTIONS_TESTS)
+      // we conditionally compile this check because our FOA implementation only
+      // exhibits the weak guarantee when swapping throws
+      //
+      // in this case, the hasher may be changed before the predicate and the
+      // arrays are swapped in which case, we can can find an element by
+      // iteration but unfortunately, it's in the wrong slot according to the
+      // new hash function so count(key) can wind up returning nothing when
+      // there really is something
       if (x1.count(key) != count) {
         BOOST_ERROR("Incorrect output of count.");
         std::cerr << x1.count(key) << "," << count << "\n";
       }
+#endif
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
       // Check that the keys are in the correct bucket and are
       // adjacent in the bucket.
       typename X::size_type bucket = x1.bucket(key);
@@ -86,6 +98,7 @@ namespace test {
           }
         }
       }
+#endif
     };
 
     // Check that size matches up.
@@ -104,6 +117,7 @@ namespace test {
     if (fabs(x1.load_factor() - load_factor) > x1.load_factor() / 64)
       BOOST_ERROR("x1.load_factor() doesn't match actual load_factor.");
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
     // Check that size in the buckets matches up.
 
     typename X::size_type bucket_size = 0;
@@ -120,6 +134,7 @@ namespace test {
       BOOST_ERROR("x1.size() doesn't match bucket size.");
       std::cout << x1.size() << "/" << bucket_size << std::endl;
     }
+#endif
   }
 }
 

test/helpers/unordered.hpp

@@ -0,0 +1,22 @@
+
+// Copyright 2022 Christian Mazakas
+// 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)
+
+#if !defined(BOOST_UNORDERED_TEST_HELPERS_UNORDERED_HEADER)
+#define BOOST_UNORDERED_TEST_HELPERS_UNORDERED_HEADER
+
+// clang-format off
+#include "prefix.hpp"
+#ifdef BOOST_UNORDERED_FOA_TESTS
+#include <boost/unordered/unordered_flat_set.hpp>
+#include <boost/unordered/unordered_flat_map.hpp>
+#include <boost/unordered/detail/implementation.hpp>
+#else
+#include <boost/unordered_set.hpp>
+#include <boost/unordered_map.hpp>
+#endif
+#include "postfix.hpp"
+// clang-format on
+
+#endif

test/objects/minimal.hpp

@@ -11,6 +11,7 @@
 #if !defined(BOOST_UNORDERED_OBJECTS_MINIMAL_HEADER)
 #define BOOST_UNORDERED_OBJECTS_MINIMAL_HEADER
 
+#include <boost/core/addressof.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/pointer_traits.hpp>
 #include <boost/move/move.hpp>
@@ -320,7 +321,7 @@ namespace test {
       bool operator!() const { return !ptr_; }
 
       static ptr pointer_to(T& p) {
-        return ptr(&p);
+        return ptr(boost::addressof(p));
       }
 
       // I'm not using the safe bool idiom because the containers should be

test/unordered/assign_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -45,6 +41,7 @@ namespace assign_tests {
       BOOST_TEST(x.empty());
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
     }
 
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "assign_tests1.2\n";
@@ -94,6 +91,7 @@ namespace assign_tests {
       BOOST_TEST(test::equivalent(x1.key_eq(), eq1));
       BOOST_TEST(test::equivalent(x2.hash_function(), hf1));
       BOOST_TEST(test::equivalent(x2.key_eq(), eq1));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
       test::check_container(x1, x2);
     }
 
@@ -199,6 +197,54 @@ namespace assign_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+  template <typename T> bool is_propagate(T*)
+  {
+    return T::allocator_type::is_propagate_on_assign;
+  }
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, std::allocator<test::object> >* test_map_std_alloc;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::allocator2<test::object> >* test_map;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_assign> >*
+    test_set_prop_assign;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_assign> >*
+    test_map_prop_assign;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_assign> >*
+    test_set_no_prop_assign;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_assign> >*
+    test_map_no_prop_assign;
+
+  UNORDERED_AUTO_TEST (check_traits) {
+    BOOST_TEST(!is_propagate(test_set));
+    BOOST_TEST(is_propagate(test_set_prop_assign));
+    BOOST_TEST(!is_propagate(test_set_no_prop_assign));
+  }
+
+  UNORDERED_TEST(assign_tests1,
+    ((test_map_std_alloc)(test_set)(test_map)(test_set_prop_assign)(test_map_prop_assign)(test_set_no_prop_assign)(test_map_no_prop_assign))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(assign_tests2,
+    ((test_set)(test_map)(test_set_prop_assign)(test_map_prop_assign)(test_set_no_prop_assign)(test_map_no_prop_assign))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
     std::allocator<test::object> >* test_map_std_alloc;
 
@@ -239,15 +285,6 @@ namespace assign_tests {
     test::cxx11_allocator<test::object, test::no_propagate_assign> >*
     test_multimap_no_prop_assign;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
-  template <typename T> bool is_propagate(T*)
-  {
-    return T::allocator_type::is_propagate_on_assign;
-  }
-
   UNORDERED_AUTO_TEST (check_traits) {
     BOOST_TEST(!is_propagate(test_set));
     BOOST_TEST(is_propagate(test_set_prop_assign));
@@ -269,13 +306,18 @@ namespace assign_tests {
                      test_set_no_prop_assign)(test_multiset_no_prop_assign)(
                      test_map_no_prop_assign)(test_multimap_no_prop_assign))(
                      (default_generator)(generate_collisions)(limited_range)))
+#endif
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 
   UNORDERED_AUTO_TEST (assign_default_initializer_list) {
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Initializer List Tests\n";
     std::initializer_list<std::pair<int const, int> > init;
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_map<int, int> x1;
+#else
     boost::unordered_map<int, int> x1;
+#endif
     x1[25] = 3;
     x1[16] = 10;
     BOOST_TEST(!x1.empty());
@@ -289,7 +331,11 @@ namespace assign_tests {
   UNORDERED_AUTO_TEST (assign_initializer_list) {
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Initializer List Tests\n";
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> x;
+#else
     boost::unordered_set<int> x;
+#endif
     x.insert(10);
     x.insert(20);
     x = {1, 2, -10};

test/unordered/at_tests.cpp

@@ -1,13 +1,10 @@
 
 // Copyright 2007-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include <string>
@@ -17,8 +14,13 @@ namespace at_tests {
   UNORDERED_AUTO_TEST (at_tests) {
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Create Map" << std::endl;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_map<std::string, int> x;
+    boost::unordered_flat_map<std::string, int> const& x_const(x);
+#else
     boost::unordered_map<std::string, int> x;
     boost::unordered_map<std::string, int> const& x_const(x);
+#endif
 
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Check empty container" << std::endl;
 

test/unordered/compile_map.cpp

@@ -1,23 +1,41 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 // This test creates the containers with members that meet their minimum
 // requirements. Makes sure everything compiles and is defined correctly.
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/minimal.hpp"
 #include "./compile_tests.hpp"
 
 // Explicit instantiation to catch compile-time errors
+#ifdef BOOST_UNORDERED_FOA_TESTS
 
+// emulates what was already done for previous tests but without leaking to
+// the detail namespace
+//
+template <typename K, typename T, typename H, typename P, typename A>
+class instantiate_flat_map
+{
+  typedef boost::unordered_flat_map<K, T, H, P, A> container;
+  container x;
+};
+
+template class instantiate_flat_map<int, int, boost::hash<int>,
+  std::equal_to<int>, test::minimal::allocator<int> >;
+
+template class instantiate_flat_map<test::minimal::assignable const,
+  test::minimal::default_assignable const,
+  test::minimal::hash<test::minimal::assignable>,
+  test::minimal::equal_to<test::minimal::assignable>,
+  test::minimal::allocator<int> >;
+
+#else
 #define INSTANTIATE(type)                                                      \
   template class boost::unordered::detail::instantiate_##type
 
@@ -35,6 +53,7 @@ INSTANTIATE(multimap)<test::minimal::assignable, test::minimal::assignable,
   test::minimal::hash<test::minimal::assignable>,
   test::minimal::equal_to<test::minimal::assignable>,
   test::minimal::allocator<int> >;
+#endif
 
 UNORDERED_AUTO_TEST (test0) {
   test::minimal::constructor_param x;
@@ -45,6 +64,19 @@ UNORDERED_AUTO_TEST (test0) {
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_map.\n";
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<int, int> int_map;
+
+  boost::unordered_flat_map<int, int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<std::pair<int const, int> > >
+    int_map2;
+
+  boost::unordered_flat_map<test::minimal::assignable,
+    test::minimal::assignable, test::minimal::hash<test::minimal::assignable>,
+    test::minimal::equal_to<test::minimal::assignable>,
+    test::minimal::allocator<value_type> >
+    map;
+#else
   boost::unordered_map<int, int> int_map;
 
   boost::unordered_map<int, int, boost::hash<int>, std::equal_to<int>,
@@ -56,11 +88,13 @@ UNORDERED_AUTO_TEST (test0) {
     test::minimal::equal_to<test::minimal::assignable>,
     test::minimal::allocator<value_type> >
     map;
+#endif
 
   container_test(int_map, std::pair<int const, int>(0, 0));
   container_test(int_map2, std::pair<int const, int>(0, 0));
   container_test(map, value);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multimap.\n";
 
   boost::unordered_multimap<int, int> int_multimap;
@@ -78,6 +112,7 @@ UNORDERED_AUTO_TEST (test0) {
   container_test(int_multimap, std::pair<int const, int>(0, 0));
   container_test(int_multimap2, std::pair<int const, int>(0, 0));
   container_test(multimap, value);
+#endif
 }
 
 UNORDERED_AUTO_TEST (equality_tests) {
@@ -85,6 +120,22 @@ UNORDERED_AUTO_TEST (equality_tests) {
     test::minimal::copy_constructible_equality_comparable>
     value_type;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<int, int> int_map;
+
+  boost::unordered_flat_map<int, int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<std::pair<int const, int> > >
+    int_map2;
+
+  boost::unordered_flat_map<
+    test::minimal::copy_constructible_equality_comparable,
+    test::minimal::copy_constructible_equality_comparable,
+    test::minimal::hash<test::minimal::copy_constructible_equality_comparable>,
+    test::minimal::equal_to<
+      test::minimal::copy_constructible_equality_comparable>,
+    test::minimal::allocator<value_type> >
+    map;
+#else
   boost::unordered_map<int, int> int_map;
 
   boost::unordered_map<int, int, boost::hash<int>, std::equal_to<int>,
@@ -98,11 +149,13 @@ UNORDERED_AUTO_TEST (equality_tests) {
       test::minimal::copy_constructible_equality_comparable>,
     test::minimal::allocator<value_type> >
     map;
+#endif
 
   equality_test(int_map);
   equality_test(int_map2);
   equality_test(map);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   boost::unordered_multimap<int, int> int_multimap;
 
   boost::unordered_multimap<int, int, boost::hash<int>, std::equal_to<int>,
@@ -121,6 +174,7 @@ UNORDERED_AUTO_TEST (equality_tests) {
   equality_test(int_multimap);
   equality_test(int_multimap2);
   equality_test(multimap);
+#endif
 }
 
 UNORDERED_AUTO_TEST (test1) {
@@ -131,11 +185,19 @@ UNORDERED_AUTO_TEST (test1) {
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_map.\n";
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<int, int> map;
+
+  boost::unordered_flat_map<int, int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<std::pair<int const, int> > >
+    map2;
+#else
   boost::unordered_map<int, int> map;
 
   boost::unordered_map<int, int, boost::hash<int>, std::equal_to<int>,
     test::minimal::cxx11_allocator<std::pair<int const, int> > >
     map2;
+#endif
 
   unordered_unique_test(map, map_value);
   unordered_map_test(map, value, value);
@@ -147,6 +209,7 @@ UNORDERED_AUTO_TEST (test1) {
   unordered_copyable_test(map2, value, map_value, hash, equal_to);
   unordered_map_functions(map2, value, value);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multimap.\n";
 
   boost::unordered_multimap<int, int> multimap;
@@ -162,6 +225,7 @@ UNORDERED_AUTO_TEST (test1) {
   unordered_equivalent_test(multimap2, map_value);
   unordered_map_test(multimap2, value, value);
   unordered_copyable_test(multimap2, value, map_value, hash, equal_to);
+#endif
 }
 
 UNORDERED_AUTO_TEST (test2) {
@@ -178,28 +242,46 @@ UNORDERED_AUTO_TEST (test2) {
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_map.\n";
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::minimal::assignable,
+    test::minimal::assignable, test::minimal::hash<test::minimal::assignable>,
+    test::minimal::equal_to<test::minimal::assignable>,
+    test::minimal::allocator<map_value_type> >
+    map;
+#else
   boost::unordered_map<test::minimal::assignable, test::minimal::assignable,
     test::minimal::hash<test::minimal::assignable>,
     test::minimal::equal_to<test::minimal::assignable>,
     test::minimal::allocator<map_value_type> >
     map;
+#endif
 
   unordered_unique_test(map, map_value);
   unordered_map_test(map, assignable, assignable);
   unordered_copyable_test(map, assignable, map_value, hash, equal_to);
   unordered_map_member_test(map, map_value);
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::minimal::assignable,
+    test::minimal::default_assignable,
+    test::minimal::hash<test::minimal::assignable>,
+    test::minimal::equal_to<test::minimal::assignable>,
+    test::minimal::allocator<map_value_type> >
+    map2;
+#else
   boost::unordered_map<test::minimal::assignable,
     test::minimal::default_assignable,
     test::minimal::hash<test::minimal::assignable>,
     test::minimal::equal_to<test::minimal::assignable>,
     test::minimal::allocator<map_value_type> >
     map2;
+#endif
 
   test::minimal::default_assignable default_assignable;
 
   unordered_map_functions(map2, assignable, default_assignable);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multimap.\n";
 
   boost::unordered_multimap<test::minimal::assignable,
@@ -212,6 +294,7 @@ UNORDERED_AUTO_TEST (test2) {
   unordered_map_test(multimap, assignable, assignable);
   unordered_copyable_test(multimap, assignable, map_value, hash, equal_to);
   unordered_map_member_test(multimap, map_value);
+#endif
 }
 
 // Test for ambiguity when using key convertible from iterator
@@ -232,6 +315,11 @@ std::size_t hash_value(lwg2059_key x)
 bool operator==(lwg2059_key x, lwg2059_key y) { return x.value == y.value; }
 
 UNORDERED_AUTO_TEST (lwg2059) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<lwg2059_key, int> x;
+  x.emplace(lwg2059_key(10), 5);
+  x.erase(x.begin());
+#else
   {
     boost::unordered_map<lwg2059_key, int> x;
     x.emplace(lwg2059_key(10), 5);
@@ -243,6 +331,7 @@ UNORDERED_AUTO_TEST (lwg2059) {
     x.emplace(lwg2059_key(10), 5);
     x.erase(x.begin());
   }
+#endif
 }
 
 RUN_TESTS()

test/unordered/compile_set.cpp

@@ -1,16 +1,13 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 // This test creates the containers with members that meet their minimum
 // requirements. Makes sure everything compiles and is defined correctly.
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/minimal.hpp"
@@ -18,6 +15,28 @@
 
 // Explicit instantiation to catch compile-time errors
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+
+// emulates what was already done for previous tests but without leaking to
+// the detail namespace
+//
+template <typename T, typename H, typename P, typename A>
+class instantiate_flat_set
+{
+  typedef boost::unordered_flat_set<T, H, P, A> container;
+  container x;
+};
+
+template class instantiate_flat_set<int, boost::hash<int>, std::equal_to<int>,
+  test::minimal::allocator<int> >;
+
+template class instantiate_flat_set<test::minimal::assignable const,
+  test::minimal::hash<test::minimal::assignable>,
+  test::minimal::equal_to<test::minimal::assignable>,
+  test::minimal::allocator<int> >;
+
+#else
+
 #define INSTANTIATE(type)                                                      \
   template class boost::unordered::detail::instantiate_##type
 
@@ -35,6 +54,21 @@ INSTANTIATE(multiset)<test::minimal::assignable,
   test::minimal::equal_to<test::minimal::assignable>,
   test::minimal::allocator<int> >;
 
+#endif
+
+UNORDERED_AUTO_TEST (type_traits) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_set<int> set_type;
+#else
+  typedef boost::unordered_set<int> set_type;
+#endif
+
+  typedef set_type::iterator iterator;
+
+  BOOST_STATIC_ASSERT(boost::is_same<int const&,
+    std::iterator_traits<iterator>::reference>::value);
+}
+
 UNORDERED_AUTO_TEST (test0) {
   test::minimal::constructor_param x;
 
@@ -42,6 +76,19 @@ UNORDERED_AUTO_TEST (test0) {
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int> int_set;
+
+  boost::unordered_flat_set<int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<int> >
+    int_set2;
+
+  boost::unordered_flat_set<test::minimal::assignable,
+    test::minimal::hash<test::minimal::assignable>,
+    test::minimal::equal_to<test::minimal::assignable>,
+    test::minimal::allocator<test::minimal::assignable> >
+    set;
+#else
   boost::unordered_set<int> int_set;
 
   boost::unordered_set<int, boost::hash<int>, std::equal_to<int>,
@@ -53,11 +100,13 @@ UNORDERED_AUTO_TEST (test0) {
     test::minimal::equal_to<test::minimal::assignable>,
     test::minimal::allocator<test::minimal::assignable> >
     set;
+#endif
 
   container_test(int_set, 0);
   container_test(int_set2, 0);
   container_test(set, assignable);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
 
   boost::unordered_multiset<int> int_multiset;
@@ -75,11 +124,27 @@ UNORDERED_AUTO_TEST (test0) {
   container_test(int_multiset, 0);
   container_test(int_multiset2, 0);
   container_test(multiset, assignable);
+#endif
 }
 
 UNORDERED_AUTO_TEST (equality_tests) {
   typedef test::minimal::copy_constructible_equality_comparable value_type;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int> int_set;
+
+  boost::unordered_flat_set<int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<int> >
+    int_set2;
+
+  boost::unordered_flat_set<
+    test::minimal::copy_constructible_equality_comparable,
+    test::minimal::hash<test::minimal::copy_constructible_equality_comparable>,
+    test::minimal::equal_to<
+      test::minimal::copy_constructible_equality_comparable>,
+    test::minimal::allocator<value_type> >
+    set;
+#else
   boost::unordered_set<int> int_set;
 
   boost::unordered_set<int, boost::hash<int>, std::equal_to<int>,
@@ -92,11 +157,13 @@ UNORDERED_AUTO_TEST (equality_tests) {
       test::minimal::copy_constructible_equality_comparable>,
     test::minimal::allocator<value_type> >
     set;
+#endif
 
   equality_test(int_set);
   equality_test(int_set2);
   equality_test(set);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   boost::unordered_multiset<int> int_multiset;
 
   boost::unordered_multiset<int, boost::hash<int>, std::equal_to<int>,
@@ -114,6 +181,7 @@ UNORDERED_AUTO_TEST (equality_tests) {
   equality_test(int_multiset);
   equality_test(int_multiset2);
   equality_test(multiset);
+#endif
 }
 
 UNORDERED_AUTO_TEST (test1) {
@@ -122,12 +190,19 @@ UNORDERED_AUTO_TEST (test1) {
   int value = 0;
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set." << std::endl;
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int> set;
 
+  boost::unordered_flat_set<int, boost::hash<int>, std::equal_to<int>,
+    test::minimal::cxx11_allocator<int> >
+    set2;
+#else
   boost::unordered_set<int> set;
 
   boost::unordered_set<int, boost::hash<int>, std::equal_to<int>,
     test::minimal::cxx11_allocator<int> >
     set2;
+#endif
 
   unordered_unique_test(set, value);
   unordered_set_test(set, value);
@@ -137,6 +212,7 @@ UNORDERED_AUTO_TEST (test1) {
   unordered_set_test(set2, value);
   unordered_copyable_test(set2, value, value, hash, equal_to);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset." << std::endl;
 
   boost::unordered_multiset<int> multiset;
@@ -152,6 +228,7 @@ UNORDERED_AUTO_TEST (test1) {
   unordered_equivalent_test(multiset2, value);
   unordered_set_test(multiset2, value);
   unordered_copyable_test(multiset2, value, value, hash, equal_to);
+#endif
 }
 
 UNORDERED_AUTO_TEST (test2) {
@@ -163,18 +240,26 @@ UNORDERED_AUTO_TEST (test2) {
   test::minimal::equal_to<test::minimal::assignable> equal_to(x);
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::minimal::assignable,
+    test::minimal::hash<test::minimal::assignable>,
+    test::minimal::equal_to<test::minimal::assignable>,
+    test::minimal::allocator<test::minimal::assignable> >
+    set;
+#else
   boost::unordered_set<test::minimal::assignable,
     test::minimal::hash<test::minimal::assignable>,
     test::minimal::equal_to<test::minimal::assignable>,
     test::minimal::allocator<test::minimal::assignable> >
     set;
+#endif
 
   unordered_unique_test(set, assignable);
   unordered_set_test(set, assignable);
   unordered_copyable_test(set, assignable, assignable, hash, equal_to);
   unordered_set_member_test(set, assignable);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
 
   boost::unordered_multiset<test::minimal::assignable,
@@ -187,6 +272,7 @@ UNORDERED_AUTO_TEST (test2) {
   unordered_set_test(multiset, assignable);
   unordered_copyable_test(multiset, assignable, assignable, hash, equal_to);
   unordered_set_member_test(multiset, assignable);
+#endif
 }
 
 UNORDERED_AUTO_TEST (movable1_tests) {
@@ -197,17 +283,25 @@ UNORDERED_AUTO_TEST (movable1_tests) {
   test::minimal::equal_to<test::minimal::movable1> equal_to(x);
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::minimal::movable1,
+    test::minimal::hash<test::minimal::movable1>,
+    test::minimal::equal_to<test::minimal::movable1>,
+    test::minimal::allocator<test::minimal::movable1> >
+    set;
+#else
   boost::unordered_set<test::minimal::movable1,
     test::minimal::hash<test::minimal::movable1>,
     test::minimal::equal_to<test::minimal::movable1>,
     test::minimal::allocator<test::minimal::movable1> >
     set;
+#endif
 
   // unordered_unique_test(set, movable1);
   unordered_set_test(set, movable1);
   unordered_movable_test(set, movable1, movable1, hash, equal_to);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
 
   boost::unordered_multiset<test::minimal::movable1,
@@ -219,6 +313,7 @@ UNORDERED_AUTO_TEST (movable1_tests) {
   // unordered_equivalent_test(multiset, movable1);
   unordered_set_test(multiset, movable1);
   unordered_movable_test(multiset, movable1, movable1, hash, equal_to);
+#endif
 }
 
 UNORDERED_AUTO_TEST (movable2_tests) {
@@ -229,17 +324,25 @@ UNORDERED_AUTO_TEST (movable2_tests) {
   test::minimal::equal_to<test::minimal::movable2> equal_to(x);
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::minimal::movable2,
+    test::minimal::hash<test::minimal::movable2>,
+    test::minimal::equal_to<test::minimal::movable2>,
+    test::minimal::allocator<test::minimal::movable2> >
+    set;
+#else
   boost::unordered_set<test::minimal::movable2,
     test::minimal::hash<test::minimal::movable2>,
     test::minimal::equal_to<test::minimal::movable2>,
     test::minimal::allocator<test::minimal::movable2> >
     set;
+#endif
 
   // unordered_unique_test(set, movable2);
   unordered_set_test(set, movable2);
   unordered_movable_test(set, movable2, movable2, hash, equal_to);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
 
   boost::unordered_multiset<test::minimal::movable2,
@@ -251,6 +354,7 @@ UNORDERED_AUTO_TEST (movable2_tests) {
   // unordered_equivalent_test(multiset, movable2);
   unordered_set_test(multiset, movable2);
   unordered_movable_test(multiset, movable2, movable2, hash, equal_to);
+#endif
 }
 
 UNORDERED_AUTO_TEST (destructible_tests) {
@@ -261,14 +365,21 @@ UNORDERED_AUTO_TEST (destructible_tests) {
   test::minimal::equal_to<test::minimal::destructible> equal_to(x);
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::minimal::destructible,
+    test::minimal::hash<test::minimal::destructible>,
+    test::minimal::equal_to<test::minimal::destructible> >
+    set;
+#else
   boost::unordered_set<test::minimal::destructible,
     test::minimal::hash<test::minimal::destructible>,
     test::minimal::equal_to<test::minimal::destructible> >
     set;
+#endif
 
   unordered_destructible_test(set);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
 
   boost::unordered_multiset<test::minimal::destructible,
@@ -277,6 +388,7 @@ UNORDERED_AUTO_TEST (destructible_tests) {
     multiset;
 
   unordered_destructible_test(multiset);
+#endif
 }
 
 // Test for ambiguity when using key convertible from iterator
@@ -297,6 +409,11 @@ std::size_t hash_value(lwg2059_key x)
 bool operator==(lwg2059_key x, lwg2059_key y) { return x.value == y.value; }
 
 UNORDERED_AUTO_TEST (lwg2059) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<lwg2059_key> x;
+  x.emplace(lwg2059_key(10));
+  x.erase(x.begin());
+#else
   {
     boost::unordered_set<lwg2059_key> x;
     x.emplace(lwg2059_key(10));
@@ -308,6 +425,7 @@ UNORDERED_AUTO_TEST (lwg2059) {
     x.emplace(lwg2059_key(10));
     x.erase(x.begin());
   }
+#endif
 }
 
 RUN_TESTS()

test/unordered/compile_tests.hpp

@@ -1,5 +1,6 @@
 
 // Copyright 2005-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
@@ -70,9 +71,19 @@ template <class X, class T> void container_test(X& r, T const&)
   typedef typename X::reference reference;
   typedef typename X::const_reference const_reference;
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::node_type node_type;
+#endif
 
   typedef typename X::allocator_type allocator_type;
+  typedef typename X::pointer pointer;
+  typedef typename X::const_pointer const_pointer;
+
+  BOOST_STATIC_ASSERT((boost::is_same<pointer,
+    typename boost::allocator_pointer<allocator_type>::type>::value));
+
+  BOOST_STATIC_ASSERT((boost::is_same<const_pointer,
+    typename boost::allocator_const_pointer<allocator_type>::type>::value));
 
   // value_type
 
@@ -97,8 +108,10 @@ template <class X, class T> void container_test(X& r, T const&)
 
   // node_type
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_STATIC_ASSERT((
     boost::is_same<allocator_type, typename node_type::allocator_type>::value));
+#endif
 
   // difference_type
 
@@ -167,6 +180,7 @@ template <class X, class T> void container_test(X& r, T const&)
   sink(X(rvalue(a_const), m));
   X c3(rvalue(a_const), m);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   // node_type
 
   implicit_construct<node_type const>();
@@ -193,6 +207,7 @@ template <class X, class T> void container_test(X& r, T const&)
   test::check_return_type<bool>::equals(n_const.empty());
   TEST_NOEXCEPT_EXPR(!n_const);
   TEST_NOEXCEPT_EXPR(n_const.empty());
+#endif
 
   // Avoid unused variable warnings:
 
@@ -262,24 +277,30 @@ template <class X, class Key> void unordered_set_test(X& r, Key const&)
 
   typedef typename X::iterator iterator;
   typedef typename X::const_iterator const_iterator;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::local_iterator local_iterator;
   typedef typename X::const_local_iterator const_local_iterator;
+#endif
   typedef typename std::iterator_traits<iterator>::pointer iterator_pointer;
   typedef typename std::iterator_traits<const_iterator>::pointer
     const_iterator_pointer;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename std::iterator_traits<local_iterator>::pointer
     local_iterator_pointer;
   typedef typename std::iterator_traits<const_local_iterator>::pointer
     const_local_iterator_pointer;
+#endif
 
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, iterator_pointer>::value));
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, const_iterator_pointer>::value));
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, local_iterator_pointer>::value));
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, const_local_iterator_pointer>::value));
+#endif
 
   // pointer_traits<iterator>
 
@@ -299,6 +320,8 @@ template <class X, class Key> void unordered_set_test(X& r, Key const&)
   BOOST_STATIC_ASSERT((boost::is_same<std::ptrdiff_t,
     typename boost::pointer_traits<const_iterator>::difference_type>::value));
 
+  (void) r;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   // pointer_traits<local_iterator>
 
   BOOST_STATIC_ASSERT((boost::is_same<local_iterator,
@@ -330,6 +353,7 @@ template <class X, class Key> void unordered_set_test(X& r, Key const&)
   r.emplace(boost::move(k_lvalue));
   node_type n1 = r.extract(r.begin());
   test::check_return_type<value_type>::equals_ref(n1.value());
+#endif
 }
 
 template <class X, class Key, class T>
@@ -345,23 +369,29 @@ void unordered_map_test(X& r, Key const& k, T const& v)
 
   typedef typename X::iterator iterator;
   typedef typename X::const_iterator const_iterator;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::local_iterator local_iterator;
   typedef typename X::const_local_iterator const_local_iterator;
+#endif
   typedef typename std::iterator_traits<iterator>::pointer iterator_pointer;
   typedef typename std::iterator_traits<const_iterator>::pointer
     const_iterator_pointer;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename std::iterator_traits<local_iterator>::pointer
     local_iterator_pointer;
   typedef typename std::iterator_traits<const_local_iterator>::pointer
     const_local_iterator_pointer;
+#endif
 
   BOOST_STATIC_ASSERT((boost::is_same<value_type*, iterator_pointer>::value));
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, const_iterator_pointer>::value));
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type*, local_iterator_pointer>::value));
   BOOST_STATIC_ASSERT(
     (boost::is_same<value_type const*, const_local_iterator_pointer>::value));
+#endif
 
   // pointer_traits<iterator>
 
@@ -381,6 +411,7 @@ void unordered_map_test(X& r, Key const& k, T const& v)
   BOOST_STATIC_ASSERT((boost::is_same<std::ptrdiff_t,
     typename boost::pointer_traits<const_iterator>::difference_type>::value));
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   // pointer_traits<local_iterator>
 
   BOOST_STATIC_ASSERT((boost::is_same<local_iterator,
@@ -409,6 +440,7 @@ void unordered_map_test(X& r, Key const& k, T const& v)
   BOOST_STATIC_ASSERT((boost::is_same<T, node_mapped_type>::value));
   // Superfluous,but just to make sure.
   BOOST_STATIC_ASSERT((!boost::is_const<node_key_type>::value));
+#endif
 
   // Calling functions
 
@@ -427,8 +459,12 @@ void unordered_map_test(X& r, Key const& k, T const& v)
   r.emplace(k_lvalue, v_lvalue);
   r.emplace(rvalue(k), rvalue(v));
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  r.emplace(std::piecewise_construct, std::make_tuple(k), std::make_tuple(v));
+#else
   r.emplace(boost::unordered::piecewise_construct, boost::make_tuple(k),
     boost::make_tuple(v));
+#endif
 
   // Emplace with hint
 
@@ -436,9 +472,15 @@ void unordered_map_test(X& r, Key const& k, T const& v)
   r.emplace_hint(r.begin(), k_lvalue, v_lvalue);
   r.emplace_hint(r.begin(), rvalue(k), rvalue(v));
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  r.emplace_hint(r.begin(), std::piecewise_construct, std::make_tuple(k),
+    std::make_tuple(v));
+#else
   r.emplace_hint(r.begin(), boost::unordered::piecewise_construct,
     boost::make_tuple(k), boost::make_tuple(v));
+#endif
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   // Extract
 
   test::check_return_type<node_type>::equals(r.extract(r.begin()));
@@ -461,6 +503,7 @@ void unordered_map_test(X& r, Key const& k, T const& v)
   node_type n = r.extract(r.begin());
   test::check_return_type<node_key_type>::equals_ref(n.key());
   test::check_return_type<node_mapped_type>::equals_ref(n.mapped());
+#endif
 }
 
 template <class X> void equality_test(X& r)
@@ -479,6 +522,7 @@ template <class X, class T> void unordered_unique_test(X& r, T const& t)
   test::check_return_type<std::pair<iterator, bool> >::equals(r.insert(t));
   test::check_return_type<std::pair<iterator, bool> >::equals(r.emplace(t));
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::node_type node_type;
   typedef typename X::insert_return_type insert_return_type;
 
@@ -503,6 +547,7 @@ template <class X, class T> void unordered_unique_test(X& r, T const& t)
   test::check_return_type<iterator>::equals(insert_return.position);
   test::check_return_type<node_type>::equals_ref(insert_return.node);
   boost::swap(insert_return, insert_return2);
+#endif
 }
 
 template <class X, class T> void unordered_equivalent_test(X& r, T const& t)
@@ -554,6 +599,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
 
   typedef typename X::iterator iterator;
   typedef typename X::const_iterator const_iterator;
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::local_iterator local_iterator;
   typedef typename X::const_local_iterator const_local_iterator;
 
@@ -590,6 +636,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
     const_local_iterator_pointer;
   typedef typename std::iterator_traits<const_local_iterator>::reference
     const_local_iterator_reference;
+#endif
   typedef typename X::allocator_type allocator_type;
 
   BOOST_STATIC_ASSERT((boost::is_same<Key, key_type>::value));
@@ -602,6 +649,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
   BOOST_STATIC_ASSERT((boost::is_same<Pred, key_equal>::value));
   test::check_return_type<bool>::convertible(eq(k, k));
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   boost::function_requires<boost::InputIteratorConcept<local_iterator> >();
   BOOST_STATIC_ASSERT(
     (boost::is_same<local_iterator_category, iterator_category>::value));
@@ -622,6 +670,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
     const_iterator_pointer>::value));
   BOOST_STATIC_ASSERT((boost::is_same<const_local_iterator_reference,
     const_iterator_reference>::value));
+#endif
 
   X a;
   allocator_type m = a.get_allocator();
@@ -667,6 +716,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
   test::check_return_type<std::pair<const_iterator, const_iterator> >::equals(
     b.equal_range(k));
   test::check_return_type<size_type>::equals(b.bucket_count());
+#ifndef BOOST_UNORDERED_FOA_TESTS
   test::check_return_type<size_type>::equals(b.max_bucket_count());
   test::check_return_type<size_type>::equals(b.bucket(k));
   test::check_return_type<size_type>::equals(b.bucket_size(0));
@@ -680,6 +730,7 @@ void unordered_test(X& x, Key& k, Hash& hf, Pred& eq)
   test::check_return_type<const_local_iterator>::equals(b.cbegin(0));
   test::check_return_type<const_local_iterator>::equals(a.cend(0));
   test::check_return_type<const_local_iterator>::equals(b.cend(0));
+#endif
 
   test::check_return_type<float>::equals(b.load_factor());
   test::check_return_type<float>::equals(b.max_load_factor());
@@ -792,7 +843,11 @@ void unordered_copyable_test(X& x, Key& k, T& t, Hash& hf, Pred& eq)
   X a10;
   a10.insert(t);
   q = a10.cbegin();
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  BOOST_STATIC_ASSERT(std::is_same<void, decltype(a10.erase(q))>::value);
+#else
   test::check_return_type<iterator>::equals(a10.erase(q));
+#endif
 
   // Avoid unused variable warnings:
 
@@ -807,10 +862,12 @@ void unordered_copyable_test(X& x, Key& k, T& t, Hash& hf, Pred& eq)
   sink(a7a);
   sink(a9a);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename X::node_type node_type;
   typedef typename X::allocator_type allocator_type;
   node_type const n_const = a.extract(a.begin());
   test::check_return_type<allocator_type>::equals(n_const.get_allocator());
+#endif
 }
 
 template <class X, class Key, class T, class Hash, class Pred>
@@ -879,7 +936,11 @@ void unordered_movable_test(X& x, Key& k, T& /* t */, Hash& hf, Pred& eq)
   T v5(v);
   a10.insert(boost::move(v5));
   q = a10.cbegin();
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  BOOST_STATIC_ASSERT(std::is_same<void, decltype(a10.erase(q))>::value);
+#else
   test::check_return_type<iterator>::equals(a10.erase(q));
+#endif
 
   // Avoid unused variable warnings:
 

test/unordered/constructor_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2010 Daniel James.
+// Copyright (C) 2022 Christian Mazakas
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -35,6 +31,7 @@ namespace constructor_tests {
 
       T x(0, hf, eq);
       BOOST_TEST(x.empty());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
       BOOST_TEST(test::equivalent(x.get_allocator(), al));
@@ -73,6 +70,7 @@ namespace constructor_tests {
 
       T x;
       BOOST_TEST(x.empty());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
       BOOST_TEST(test::equivalent(x.get_allocator(), al));
@@ -140,6 +138,7 @@ namespace constructor_tests {
 
       T x(0, hf, eq, al);
       BOOST_TEST(x.empty());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
       BOOST_TEST(test::equivalent(x.get_allocator(), al));
@@ -166,6 +165,7 @@ namespace constructor_tests {
 
       T x(al);
       BOOST_TEST(x.empty());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
       BOOST_TEST(test::equivalent(x.get_allocator(), al));
@@ -325,6 +325,7 @@ namespace constructor_tests {
 
       T x(list);
       BOOST_TEST(x.empty());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
       BOOST_TEST(test::equivalent(x.hash_function(), hf));
       BOOST_TEST(test::equivalent(x.key_eq(), eq));
       BOOST_TEST(test::equivalent(x.get_allocator(), al));
@@ -380,6 +381,104 @@ namespace constructor_tests {
 #endif
   }
 
+  template <class T>
+  void no_alloc_default_construct_test(T*, test::random_generator)
+  {
+    UNORDERED_SUB_TEST("Construct 1")
+    {
+      T x;
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+    }
+
+    UNORDERED_SUB_TEST("Construct 2")
+    {
+      {
+        T x(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        T x(1);
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+
+    UNORDERED_SUB_TEST("Construct 3")
+    {
+      test::random_values<T> v;
+      T x(v.begin(), v.end());
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+    }
+
+    UNORDERED_SUB_TEST("Construct 4")
+    {
+      {
+        test::random_values<T> v;
+        T x(v.begin(), v.end(), 0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        test::random_values<T> v;
+        T x(v.begin(), v.end(), 1);
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+
+    UNORDERED_SUB_TEST("Construct 5")
+    {
+      typename T::allocator_type al;
+
+      {
+        T x(al);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+
+    UNORDERED_SUB_TEST("Construct 6")
+    {
+      typename T::allocator_type al;
+
+      T x(0, al);
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+    }
+
+#if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
+    UNORDERED_SUB_TEST("Initializer list 1")
+    {
+      std::initializer_list<typename T::value_type> list;
+      T x(list);
+      BOOST_TEST_EQ(x.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+    }
+
+    UNORDERED_SUB_TEST("Initializer list 2")
+    {
+      {
+        std::initializer_list<typename T::value_type> list;
+        T x(list, 0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        std::initializer_list<typename T::value_type> list;
+        T x(list, 1);
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+#endif
+  }
+
   template <class T>
   void map_constructor_test(T*, test::random_generator const& generator)
   {
@@ -394,6 +493,35 @@ namespace constructor_tests {
     test::check_equivalent_keys(x);
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, std::allocator<test::object> >* test_map_std_alloc;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::allocator2<test::object> >* test_map;
+
+  UNORDERED_TEST(constructor_tests1,
+    ((test_map_std_alloc)(test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(constructor_tests2,
+    ((test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(map_constructor_test,
+    ((test_map_std_alloc)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(no_alloc_default_construct_test,
+    ((test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
     std::allocator<test::object> >* test_map_std_alloc;
 
@@ -406,10 +534,6 @@ namespace constructor_tests {
   boost::unordered_multimap<test::object, test::object, test::hash,
     test::equal_to, test::allocator1<test::object> >* test_multimap;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_TEST(constructor_tests1,
     ((test_map_std_alloc)(test_set)(test_multiset)(test_map)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
@@ -422,11 +546,20 @@ namespace constructor_tests {
     ((test_map_std_alloc)(test_map)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
 
+  UNORDERED_TEST(no_alloc_default_construct_test,
+    ((test_set)(test_multiset)(test_map)(test_multimap))(
+      (default_generator)(generate_collisions)(limited_range)))
+#endif
+
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 
   UNORDERED_AUTO_TEST (test_default_initializer_list) {
     std::initializer_list<int> init;
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> x1 = init;
+#else
     boost::unordered_set<int> x1 = init;
+#endif
     BOOST_TEST(x1.empty());
   }
 
@@ -435,7 +568,12 @@ namespace constructor_tests {
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 
   UNORDERED_AUTO_TEST (test_initializer_list) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> x1 = {2, 10, 45, -5};
+#else
     boost::unordered_set<int> x1 = {2, 10, 45, -5};
+#endif
+
     BOOST_TEST(x1.find(10) != x1.end());
     BOOST_TEST(x1.find(46) == x1.end());
   }

test/unordered/contains_tests.cpp

@@ -1,13 +1,8 @@
-// Copyright 2021 Christian Mazakas.
+// Copyright 2021-2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 
@@ -129,6 +124,20 @@ template <class UnorderedMap> void test_map_non_transparent_contains()
 
 void test_map()
 {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_map<key, int, transparent_hasher,
+    transparent_key_equal>
+    transparent_map;
+
+  typedef boost::unordered_flat_map<key, int, transparent_hasher, key_equal>
+    non_transparent_map1;
+
+  typedef boost::unordered_flat_map<key, int, hasher, transparent_key_equal>
+    non_transparent_map2;
+
+  typedef boost::unordered_flat_map<key, int, hasher, key_equal>
+    non_transparent_map3;
+#else
   typedef boost::unordered_map<key, int, transparent_hasher,
     transparent_key_equal>
     transparent_map;
@@ -141,6 +150,7 @@ void test_map()
 
   typedef boost::unordered_map<key, int, hasher, key_equal>
     non_transparent_map3;
+#endif
 
   test_map_transparent_contains<transparent_map>();
   test_map_non_transparent_contains<non_transparent_map1>();
@@ -148,6 +158,7 @@ void test_map()
   test_map_non_transparent_contains<non_transparent_map3>();
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 void test_multimap()
 {
   typedef boost::unordered_multimap<key, int, transparent_hasher,
@@ -168,6 +179,7 @@ void test_multimap()
   test_map_non_transparent_contains<non_transparent_multimap2>();
   test_map_non_transparent_contains<non_transparent_multimap3>();
 }
+#endif
 
 template <class UnorderedSet> void test_set_transparent_contains()
 {
@@ -231,6 +243,18 @@ template <class UnorderedSet> void test_set_non_transparent_contains()
 
 void test_set()
 {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_set<key, transparent_hasher,
+    transparent_key_equal>
+    transparent_set;
+
+  typedef boost::unordered_flat_set<key, transparent_hasher, key_equal>
+    non_transparent_set1;
+  typedef boost::unordered_flat_set<key, hasher, transparent_key_equal>
+    non_transparent_set2;
+  typedef boost::unordered_flat_set<key, hasher, key_equal>
+    non_transparent_set3;
+#else
   typedef boost::unordered_set<key, transparent_hasher, transparent_key_equal>
     transparent_set;
 
@@ -239,6 +263,7 @@ void test_set()
   typedef boost::unordered_set<key, hasher, transparent_key_equal>
     non_transparent_set2;
   typedef boost::unordered_set<key, hasher, key_equal> non_transparent_set3;
+#endif
 
   test_set_transparent_contains<transparent_set>();
   test_set_non_transparent_contains<non_transparent_set1>();
@@ -246,6 +271,7 @@ void test_set()
   test_set_non_transparent_contains<non_transparent_set3>();
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 void test_multiset()
 {
   typedef boost::unordered_multiset<key, transparent_hasher,
@@ -264,11 +290,15 @@ void test_multiset()
   test_set_non_transparent_contains<non_transparent_multiset2>();
   test_set_non_transparent_contains<non_transparent_multiset3>();
 }
+#endif
 
 UNORDERED_AUTO_TEST (contains_) { // avoid -Wshadow warning with `bool contains`
   test_map();
-  test_multimap();
   test_set();
+#ifndef BOOST_UNORDERED_FOA_TESTS
+  test_multimap();
+  test_multiset();
+#endif
 }
 
 RUN_TESTS()

test/unordered/copy_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright (C) 2022 Christian Mazakas
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -43,6 +39,23 @@ namespace copy_tests {
       BOOST_TEST(x.max_load_factor() == y.max_load_factor());
       BOOST_TEST(test::selected_count(y.get_allocator()) ==
                  (allocator_type::is_select_on_copy));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
+      test::check_equivalent_keys(y);
+    }
+
+    {
+      test::check_instances check_;
+
+      T x(0);
+      T y(x);
+      BOOST_TEST(y.empty());
+      BOOST_TEST(test::equivalent(y.hash_function(), hf));
+      BOOST_TEST(test::equivalent(y.key_eq(), eq));
+      BOOST_TEST(test::equivalent(y.get_allocator(), al));
+      BOOST_TEST(x.max_load_factor() == y.max_load_factor());
+      BOOST_TEST(test::selected_count(y.get_allocator()) ==
+                 (allocator_type::is_select_on_copy));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
       test::check_equivalent_keys(y);
     }
 
@@ -91,6 +104,22 @@ namespace copy_tests {
 
     typedef typename T::allocator_type allocator_type;
 
+    {
+      test::check_instances check_;
+
+      T x(0, hf, eq, al);
+      T y(x);
+      BOOST_TEST(y.empty());
+      BOOST_TEST(test::equivalent(y.hash_function(), hf));
+      BOOST_TEST(test::equivalent(y.key_eq(), eq));
+      BOOST_TEST(test::equivalent(y.get_allocator(), al));
+      BOOST_TEST(x.max_load_factor() == y.max_load_factor());
+      BOOST_TEST(test::selected_count(y.get_allocator()) ==
+                 (allocator_type::is_select_on_copy));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
+      test::check_equivalent_keys(y);
+    }
+
     {
       test::check_instances check_;
 
@@ -106,6 +135,21 @@ namespace copy_tests {
       test::check_equivalent_keys(y);
     }
 
+    {
+      test::check_instances check_;
+
+      T x(0, hf, eq, al);
+      T y(x, al2);
+      BOOST_TEST(y.empty());
+      BOOST_TEST(test::equivalent(y.hash_function(), hf));
+      BOOST_TEST(test::equivalent(y.key_eq(), eq));
+      BOOST_TEST(test::equivalent(y.get_allocator(), al2));
+      BOOST_TEST(x.max_load_factor() == y.max_load_factor());
+      BOOST_TEST(test::selected_count(y.get_allocator()) == 0);
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
+      test::check_equivalent_keys(y);
+    }
+
     {
       test::check_instances check_;
 
@@ -120,6 +164,22 @@ namespace copy_tests {
       test::check_equivalent_keys(y);
     }
 
+    {
+      test::check_instances check_;
+
+      test::random_values<T> v;
+
+      T x(v.begin(), v.end(), 0, hf, eq, al);
+      T y(x);
+      test::unordered_equivalence_tester<T> equivalent(x);
+      BOOST_TEST(equivalent(y));
+      test::check_equivalent_keys(y);
+      BOOST_TEST(test::selected_count(y.get_allocator()) ==
+                 (allocator_type::is_select_on_copy));
+      BOOST_TEST(test::equivalent(y.get_allocator(), al));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
+    }
+
     {
       test::check_instances check_;
 
@@ -135,6 +195,21 @@ namespace copy_tests {
       BOOST_TEST(test::equivalent(y.get_allocator(), al));
     }
 
+    {
+      test::check_instances check_;
+
+      test::random_values<T> v;
+
+      T x(v.begin(), v.end(), 0, hf, eq, al);
+      T y(x, al2);
+      test::unordered_equivalence_tester<T> equivalent(x);
+      BOOST_TEST(equivalent(y));
+      test::check_equivalent_keys(y);
+      BOOST_TEST(test::selected_count(y.get_allocator()) == 0);
+      BOOST_TEST(test::equivalent(y.get_allocator(), al2));
+      BOOST_TEST(test::detail::tracker.count_allocations == 0);
+    }
+
     {
       test::check_instances check_;
 
@@ -150,6 +225,38 @@ namespace copy_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::allocator1<test::object> >* test_map;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::select_copy> >*
+    test_set_select_copy;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::cxx11_allocator<test::object, test::select_copy> >*
+    test_map_select_copy;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_select_copy> >*
+    test_set_no_select_copy;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::cxx11_allocator<test::object, test::no_select_copy> >*
+    test_map_no_select_copy;
+
+  UNORDERED_TEST(copy_construct_tests1,
+    ((test_set)(test_map)(test_set_select_copy)(test_map_select_copy)(test_set_no_select_copy)(test_map_no_select_copy))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(copy_construct_tests2,
+    ((test_set)(test_map)(test_set_select_copy)(test_map_select_copy)(test_set_no_select_copy)(test_map_no_select_copy))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::allocator1<test::object> >* test_set;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
@@ -185,25 +292,14 @@ namespace copy_tests {
     test::equal_to, test::cxx11_allocator<test::object, test::no_select_copy> >*
     test_multimap_no_select_copy;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_TEST(copy_construct_tests1,
-    ((test_set)(test_multiset)(test_map)(test_multimap)(test_set_select_copy)(
-      test_multiset_select_copy)(test_map_select_copy)(
-      test_multimap_select_copy)(test_set_no_select_copy)(
-      test_multiset_no_select_copy)(test_map_no_select_copy)(
-      test_multimap_no_select_copy))(
+    ((test_set)(test_multiset)(test_map)(test_multimap)(test_set_select_copy)(test_multiset_select_copy)(test_map_select_copy)(test_multimap_select_copy)(test_set_no_select_copy)(test_multiset_no_select_copy)(test_map_no_select_copy)(test_multimap_no_select_copy))(
       (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(copy_construct_tests2,
-    ((test_set)(test_multiset)(test_map)(test_multimap)(test_set_select_copy)(
-      test_multiset_select_copy)(test_map_select_copy)(
-      test_multimap_select_copy)(test_set_no_select_copy)(
-      test_multiset_no_select_copy)(test_map_no_select_copy)(
-      test_multimap_no_select_copy))(
+    ((test_set)(test_multiset)(test_map)(test_multimap)(test_set_select_copy)(test_multiset_select_copy)(test_map_select_copy)(test_multimap_select_copy)(test_set_no_select_copy)(test_multiset_no_select_copy)(test_map_no_select_copy)(test_multimap_no_select_copy))(
       (default_generator)(generate_collisions)(limited_range)))
-}
+#endif
+} // namespace copy_tests
 
 RUN_TESTS()

test/unordered/emplace_tests.cpp

@@ -1,14 +1,10 @@
 //
 // Copyright 2016 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include <boost/functional/hash/hash.hpp>
 #include "../helpers/test.hpp"
@@ -46,47 +42,56 @@ namespace emplace_tests {
     A8 a8;
     A9 a9;
 
-    emplace_value(A0 const& b0, A1 const& b1) : arg_count(2), a0(b0), a1(b1) {}
+    emplace_value(A0 const& b0, A1 const& b1)
+        : arg_count(2), a0(b0), a1(b1), a2('\0'), a3(-1), a4(-1), a5(-1),
+          a6(-1), a7(-1), a8(-1), a9(-1)
+    {
+    }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2)
-        : arg_count(3), a0(b0), a1(b1), a2(b2)
+        : arg_count(3), a0(b0), a1(b1), a2(b2), a3(-1), a4(-1), a5(-1), a6(-1),
+          a7(-1), a8(-1), a9(-1)
     {
     }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3)
-        : arg_count(4), a0(b0), a1(b1), a2(b2), a3(b3)
+        : arg_count(4), a0(b0), a1(b1), a2(b2), a3(b3), a4(-1), a5(-1), a6(-1),
+          a7(-1), a8(-1), a9(-1)
     {
     }
 
     emplace_value(
       A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3, A4 const& b4)
-        : arg_count(5), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4)
+        : arg_count(5), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(-1), a6(-1),
+          a7(-1), a8(-1), a9(-1)
     {
     }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3,
       A4 const& b4, A5 const& b5)
-        : arg_count(6), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5)
+        : arg_count(6), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5), a6(-1),
+          a7(-1), a8(-1), a9(-1)
     {
     }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3,
       A4 const& b4, A5 const& b5, A6 const& b6)
-        : arg_count(7), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5), a6(b6)
+        : arg_count(7), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5), a6(b6),
+          a7(-1), a8(-1), a9(-1)
     {
     }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3,
       A4 const& b4, A5 const& b5, A6 const& b6, A7 const& b7)
         : arg_count(8), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5), a6(b6),
-          a7(b7)
+          a7(b7), a8(-1), a9(-1)
     {
     }
 
     emplace_value(A0 const& b0, A1 const& b1, A2 const& b2, A3 const& b3,
       A4 const& b4, A5 const& b5, A6 const& b6, A7 const& b7, A8 const& b8)
         : arg_count(9), a0(b0), a1(b1), a2(b2), a3(b3), a4(b4), a5(b5), a6(b6),
-          a7(b7), a8(b8)
+          a7(b7), a8(b8), a9(-1)
     {
     }
 
@@ -162,16 +167,29 @@ namespace emplace_tests {
       return true;
     }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    emplace_value() = delete;
+    emplace_value(emplace_value const&) = default;
+    emplace_value(emplace_value&&) = default;
+#else
   private:
     emplace_value();
     emplace_value(emplace_value const&);
+#endif
+
   };
 
   UNORDERED_AUTO_TEST (emplace_set) {
     test::check_instances check_;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_set<emplace_value,
+      boost::hash<emplace_value> >
+      container;
+#else
     typedef boost::unordered_set<emplace_value, boost::hash<emplace_value> >
       container;
+#endif
     typedef container::iterator iterator;
     typedef std::pair<iterator, bool> return_type;
     container x(10);
@@ -187,7 +205,15 @@ namespace emplace_tests {
     BOOST_TEST(*r1.first == v1);
     BOOST_TEST(r1.first == x.find(v1));
     BOOST_TEST_EQ(check_.instances(), 2);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    // 1 from v1
+    // 1 from constructing the value_type() so we can pluck the key
+    // 1 from move-constructing which invokes the counted_object base
+    // constructor
+    BOOST_TEST_EQ(check_.constructions(), 3);
+#else
     BOOST_TEST_EQ(check_.constructions(), 2);
+#endif
 
     // 3 args
 
@@ -198,7 +224,11 @@ namespace emplace_tests {
     BOOST_TEST(*r1.first == v2);
     BOOST_TEST(r1.first == x.find(v2));
     BOOST_TEST_EQ(check_.instances(), 4);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  BOOST_TEST_EQ(check_.constructions(), 6);
+#else
     BOOST_TEST_EQ(check_.constructions(), 4);
+#endif
 
     // 7 args with hint + duplicate
 
@@ -208,7 +238,11 @@ namespace emplace_tests {
     BOOST_TEST(*i1 == v3);
     BOOST_TEST(i1 == x.find(v3));
     BOOST_TEST_EQ(check_.instances(), 6);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST_EQ(check_.constructions(), 9);
+#else
     BOOST_TEST_EQ(check_.constructions(), 6);
+#endif
 
     r2 = x.emplace(25, "something", 'z', 4, 5, 6, 7);
     BOOST_TEST_EQ(x.size(), 3u);
@@ -218,7 +252,11 @@ namespace emplace_tests {
     // whether it can emplace, so there's an extra construction
     // here.
     BOOST_TEST_EQ(check_.instances(), 6);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST_EQ(check_.constructions(), 10);
+#else
     BOOST_TEST_EQ(check_.constructions(), 7);
+#endif
 
     // 10 args + hint duplicate
 
@@ -230,7 +268,11 @@ namespace emplace_tests {
     BOOST_TEST(*r1.first == v4);
     BOOST_TEST(r1.first == x.find(v4));
     BOOST_TEST_EQ(check_.instances(), 8);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST_EQ(check_.constructions(), 13);
+#else
     BOOST_TEST_EQ(check_.constructions(), 9);
+#endif
 
     BOOST_TEST(
       r1.first == x.emplace_hint(r1.first, 10, "", 'a', 4, 5, 6, 7, 8, 9, 10));
@@ -239,7 +281,11 @@ namespace emplace_tests {
     BOOST_TEST(
       r1.first == x.emplace_hint(x.end(), 10, "", 'a', 4, 5, 6, 7, 8, 9, 10));
     BOOST_TEST_EQ(check_.instances(), 8);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST_EQ(check_.constructions(), 16);
+#else
     BOOST_TEST_EQ(check_.constructions(), 12);
+#endif
 
     BOOST_TEST_EQ(x.size(), 4u);
     BOOST_TEST(x.count(v1) == 1);
@@ -248,6 +294,7 @@ namespace emplace_tests {
     BOOST_TEST(x.count(v4) == 1);
   }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (emplace_multiset) {
     test::check_instances check_;
 
@@ -325,20 +372,79 @@ namespace emplace_tests {
     BOOST_TEST_EQ(x.count(v2), 2u);
     BOOST_TEST_EQ(x.count(v3), 2u);
   }
+#endif
 
   UNORDERED_AUTO_TEST (emplace_map) {
     test::check_instances check_;
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_map<emplace_value, emplace_value,
+      boost::hash<emplace_value> >
+      container;
+#else
     typedef boost::unordered_map<emplace_value, emplace_value,
       boost::hash<emplace_value> >
       container;
+#endif
     typedef container::iterator iterator;
     typedef std::pair<iterator, bool> return_type;
     container x(10);
     return_type r1, r2;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
     // 5/8 args + duplicate
+    emplace_value k1(5, "", 'b', 4, 5);
+    emplace_value m1(8, "xxx", 'z', 4, 5, 6, 7, 8);
+    r1 = x.emplace(std::piecewise_construct, std::make_tuple(5, "", 'b', 4, 5),
+      std::make_tuple(8, "xxx", 'z', 4, 5, 6, 7, 8));
+    BOOST_TEST_EQ(x.size(), 1u);
+    BOOST_TEST(r1.second);
+    BOOST_TEST(x.find(k1) == r1.first);
+    BOOST_TEST(x.find(k1)->second == m1);
+    BOOST_TEST_EQ(check_.instances(), 4);
+    BOOST_TEST_EQ(check_.constructions(), 6);
 
+    r2 = x.emplace(std::piecewise_construct, std::make_tuple(5, "", 'b', 4, 5),
+      std::make_tuple(8, "xxx", 'z', 4, 5, 6, 7, 8));
+    BOOST_TEST_EQ(x.size(), 1u);
+    BOOST_TEST(!r2.second);
+    BOOST_TEST(r1.first == r2.first);
+    BOOST_TEST(x.find(k1)->second == m1);
+    BOOST_TEST_EQ(check_.instances(), 4);
+    // constructions could possibly be 5 if the implementation only
+    // constructed the key.
+    BOOST_TEST_EQ(check_.constructions(), 8);
+
+    // 9/3 args + duplicates with hints, different mapped value.
+
+    emplace_value k2(9, "", 'b', 4, 5, 6, 7, 8, 9);
+    emplace_value m2(3, "aaa", 'm');
+    r1 = x.emplace(std::piecewise_construct,
+      std::make_tuple(9, "", 'b', 4, 5, 6, 7, 8, 9),
+      std::make_tuple(3, "aaa", 'm'));
+    BOOST_TEST_EQ(x.size(), 2u);
+    BOOST_TEST(r1.second);
+    BOOST_TEST(r1.first->first.arg_count == 9);
+    BOOST_TEST(r1.first->second.arg_count == 3);
+    BOOST_TEST(x.find(k2) == r1.first);
+    BOOST_TEST(x.find(k2)->second == m2);
+    BOOST_TEST_EQ(check_.instances(), 8);
+    BOOST_TEST_EQ(check_.constructions(), 14);
+
+    BOOST_TEST(r1.first == x.emplace_hint(r1.first, std::piecewise_construct,
+                             std::make_tuple(9, "", 'b', 4, 5, 6, 7, 8, 9),
+                             std::make_tuple(15, "jkjk")));
+    BOOST_TEST(r1.first == x.emplace_hint(r2.first, std::piecewise_construct,
+                             std::make_tuple(9, "", 'b', 4, 5, 6, 7, 8, 9),
+                             std::make_tuple(275, "xxx", 'm', 6)));
+    BOOST_TEST(r1.first == x.emplace_hint(x.end(), std::piecewise_construct,
+                             std::make_tuple(9, "", 'b', 4, 5, 6, 7, 8, 9),
+                             std::make_tuple(-10, "blah blah", '\0')));
+    BOOST_TEST_EQ(x.size(), 2u);
+    BOOST_TEST(x.find(k2)->second == m2);
+    BOOST_TEST_EQ(check_.instances(), 8);
+    BOOST_TEST_EQ(check_.constructions(), 20);
+#else
+    // 5/8 args + duplicate
     emplace_value k1(5, "", 'b', 4, 5);
     emplace_value m1(8, "xxx", 'z', 4, 5, 6, 7, 8);
     r1 = x.emplace(boost::unordered::piecewise_construct,
@@ -395,8 +501,10 @@ namespace emplace_tests {
     BOOST_TEST(x.find(k2)->second == m2);
     BOOST_TEST_EQ(check_.instances(), 8);
     BOOST_TEST_EQ(check_.constructions(), 16);
+#endif
   }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (emplace_multimap) {
     test::check_instances check_;
 
@@ -461,11 +569,15 @@ namespace emplace_tests {
     BOOST_TEST_EQ(check_.instances(), 20);
     BOOST_TEST_EQ(check_.constructions(), 20);
   }
+#endif
 
   UNORDERED_AUTO_TEST (try_emplace) {
     test::check_instances check_;
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_map<int, emplace_value> container;
+#else
     typedef boost::unordered_map<int, emplace_value> container;
+#endif
     typedef container::iterator iterator;
     typedef std::pair<iterator, bool> return_type;
     container x(10);

test/unordered/equality_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2008-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include <boost/preprocessor/seq.hpp>
 #include <list>
@@ -30,14 +26,27 @@ namespace equality_tests {
     }
   };
 
-#define UNORDERED_EQUALITY_SET_TEST(seq1, op, seq2)                            \
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  using boost_unordered_set =
+    boost::unordered_flat_set<int, mod_compare, mod_compare>;
+
+  using boost_unordered_map =
+    boost::unordered_flat_map<int, int, mod_compare, mod_compare>;
+
+#define UNORDERED_EQUALITY_MULTISET_TEST(seq1, op, seq2)                       \
   {                                                                            \
-    boost::unordered_set<int, mod_compare, mod_compare> set1, set2;            \
-    BOOST_PP_SEQ_FOR_EACH(UNORDERED_SET_INSERT, set1, seq1)                    \
-    BOOST_PP_SEQ_FOR_EACH(UNORDERED_SET_INSERT, set2, seq2)                    \
-    BOOST_TEST(set1 op set2);                                                  \
   }
 
+#define UNORDERED_EQUALITY_MULTIMAP_TEST(seq1, op, seq2)                       \
+  {                                                                            \
+  }
+#else
+  typedef boost::unordered_set<int, mod_compare, mod_compare>
+    boost_unordered_set;
+
+  typedef boost::unordered_map<int, int, mod_compare, mod_compare>
+    boost_unordered_map;
+
 #define UNORDERED_EQUALITY_MULTISET_TEST(seq1, op, seq2)                       \
   {                                                                            \
     boost::unordered_multiset<int, mod_compare, mod_compare> set1, set2;       \
@@ -46,17 +55,26 @@ namespace equality_tests {
     BOOST_TEST(set1 op set2);                                                  \
   }
 
-#define UNORDERED_EQUALITY_MAP_TEST(seq1, op, seq2)                            \
+#define UNORDERED_EQUALITY_MULTIMAP_TEST(seq1, op, seq2)                       \
   {                                                                            \
-    boost::unordered_map<int, int, mod_compare, mod_compare> map1, map2;       \
+    boost::unordered_multimap<int, int, mod_compare, mod_compare> map1, map2;  \
     BOOST_PP_SEQ_FOR_EACH(UNORDERED_MAP_INSERT, map1, seq1)                    \
     BOOST_PP_SEQ_FOR_EACH(UNORDERED_MAP_INSERT, map2, seq2)                    \
     BOOST_TEST(map1 op map2);                                                  \
   }
+#endif
 
-#define UNORDERED_EQUALITY_MULTIMAP_TEST(seq1, op, seq2)                       \
+#define UNORDERED_EQUALITY_SET_TEST(seq1, op, seq2)                            \
   {                                                                            \
-    boost::unordered_multimap<int, int, mod_compare, mod_compare> map1, map2;  \
+    boost_unordered_set set1, set2;            \
+    BOOST_PP_SEQ_FOR_EACH(UNORDERED_SET_INSERT, set1, seq1)                    \
+    BOOST_PP_SEQ_FOR_EACH(UNORDERED_SET_INSERT, set2, seq2)                    \
+    BOOST_TEST(set1 op set2);                                                  \
+  }
+
+#define UNORDERED_EQUALITY_MAP_TEST(seq1, op, seq2)                            \
+  {                                                                            \
+    boost_unordered_map map1, map2;                                            \
     BOOST_PP_SEQ_FOR_EACH(UNORDERED_MAP_INSERT, map1, seq1)                    \
     BOOST_PP_SEQ_FOR_EACH(UNORDERED_MAP_INSERT, map2, seq2)                    \
     BOOST_TEST(map1 op map2);                                                  \
@@ -67,7 +85,11 @@ namespace equality_tests {
   map.insert(std::pair<int const, int> BOOST_PP_SEQ_TO_TUPLE(item));
 
   UNORDERED_AUTO_TEST (equality_size_tests) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> x1, x2;
+#else
     boost::unordered_set<int> x1, x2;
+#endif
     BOOST_TEST(x1 == x2);
     BOOST_TEST(!(x1 != x2));
 
@@ -134,7 +156,7 @@ namespace equality_tests {
   // different hash functions but the same equality predicate.
 
   UNORDERED_AUTO_TEST (equality_different_hash_test) {
-    typedef boost::unordered_set<int, mod_compare, mod_compare> set;
+    typedef boost_unordered_set set;
     set set1(0, mod_compare(false), mod_compare(false));
     set set2(0, mod_compare(true), mod_compare(true));
     BOOST_TEST(set1 == set2);

test/unordered/equivalent_keys_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include <algorithm>
@@ -38,8 +34,11 @@ void test_equal_insertion(Iterator begin, Iterator end)
 UNORDERED_AUTO_TEST (set_tests) {
   int values[][5] = {{1}, {54, 23}, {-13, 65}, {77, 77}, {986, 25, 986}};
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_set<int> set;
+#else
   typedef boost::unordered_set<int> set;
-  typedef boost::unordered_multiset<int> multiset;
+#endif
 
   test_equal_insertion<set>(values[0], values[0] + 1);
   test_equal_insertion<set>(values[1], values[1] + 2);
@@ -47,6 +46,7 @@ UNORDERED_AUTO_TEST (set_tests) {
   test_equal_insertion<set>(values[3], values[3] + 2);
   test_equal_insertion<set>(values[4], values[4] + 3);
 
+  typedef boost::unordered_multiset<int> multiset;
   test_equal_insertion<multiset>(values[0], values[0] + 1);
   test_equal_insertion<multiset>(values[1], values[1] + 2);
   test_equal_insertion<multiset>(values[2], values[2] + 2);
@@ -66,12 +66,17 @@ UNORDERED_AUTO_TEST (map_tests) {
   v[2].push_back(std::pair<int const, int>(432, 24));
 
   for (int i = 0; i < 5; ++i)
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    test_equal_insertion<boost::unordered_flat_map<int, int> >(
+      v[i].begin(), v[i].end());
+#else
     test_equal_insertion<boost::unordered_map<int, int> >(
       v[i].begin(), v[i].end());
 
   for (int i2 = 0; i2 < 5; ++i2)
     test_equal_insertion<boost::unordered_multimap<int, int> >(
       v[i2].begin(), v[i2].end());
+#endif
 }
 
 RUN_TESTS()

test/unordered/erase_if.cpp

@@ -2,12 +2,7 @@
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 
@@ -23,36 +18,13 @@
 namespace test {
   struct is_even
   {
-    is_even() {}
-
-#if BOOST_CXX_VERSION >= 201703L
-    // immovable for C++17
-    is_even(is_even const&) = delete;
-    is_even(is_even&&) = delete;
-
-    is_even& operator=(is_even const&) = delete;
-    is_even& operator=(is_even&&) = delete;
-#elif BOOST_CXX_VERSION >= 201103L
-    // move-only for C++11
-    is_even(is_even const&) = delete;
-    is_even(is_even&&) = default;
-
-    is_even& operator=(is_even const&) = delete;
-    is_even& operator=(is_even&&) = default;
-#else
-    // copyable otherwise
-    is_even(is_even const&) {}
-    is_even& operator=(is_even const&) { return *this; }
-#endif
-
-    bool operator()(
-      std::pair<std::string const, int>& key_value) UNORDERED_LVALUE_QUAL
+    bool operator()(std::pair<std::string const, int>& key_value)
     {
       int const v = key_value.second;
       return (v % 2 == 0);
     }
 
-    bool operator()(int const& value) UNORDERED_LVALUE_QUAL
+    bool operator()(int const& value)
     {
       int const v = value;
       return (v % 2 == 0);
@@ -61,37 +33,13 @@ namespace test {
 
   struct is_too_large
   {
-    is_too_large() {}
-
-#if BOOST_CXX_VERSION >= 201703L
-    // immovable for C++17
-    is_too_large(is_too_large const&) = delete;
-    is_too_large(is_too_large&&) = delete;
-
-    is_too_large& operator=(is_too_large const&) = delete;
-    is_too_large& operator=(is_too_large&&) = delete;
-#elif BOOST_CXX_VERSION >= 201103L
-    // move-only for C++11
-    is_too_large(is_too_large const&) = delete;
-    is_too_large(is_too_large&&) = default;
-
-    is_too_large& operator=(is_too_large const&) = delete;
-    is_too_large& operator=(is_too_large&&) = default;
-#else
-    // copyable otherwise
-    is_too_large(is_too_large const&) {}
-
-    is_too_large& operator=(is_too_large const&) { return *this; }
-#endif
-
-    bool operator()(
-      std::pair<std::string const, int>& key_value) UNORDERED_LVALUE_QUAL
+    bool operator()(std::pair<std::string const, int>& key_value)
     {
       int const v = key_value.second;
       return v >= 1000;
     }
 
-    bool operator()(int const& value) UNORDERED_LVALUE_QUAL
+    bool operator()(int const& value)
     {
       int const v = value;
       return v >= 1000;
@@ -159,11 +107,16 @@ template <class UnorderedSet> void test_set_erase_if()
 }
 
 UNORDERED_AUTO_TEST (unordered_erase_if) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  test_map_erase_if<boost::unordered_flat_map<std::string, int> >();
+  test_set_erase_if<boost::unordered_flat_set<int> >();
+#else
   test_map_erase_if<boost::unordered_map<std::string, int> >();
   test_map_erase_if<boost::unordered_multimap<std::string, int> >();
 
   test_set_erase_if<boost::unordered_set<int> >();
   test_set_erase_if<boost::unordered_multiset<int> >();
+#endif
 }
 
 RUN_TESTS()

test/unordered/erase_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -27,7 +23,9 @@ namespace erase_tests {
   template <class Container>
   void erase_tests1(Container*, test::random_generator generator)
   {
+#ifndef BOOST_UNORDERED_FOA_TESTS
     typedef typename Container::iterator iterator;
+#endif
     typedef typename Container::const_iterator c_iterator;
 
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Erase by key.\n";
@@ -61,9 +59,13 @@ namespace erase_tests {
       while (size > 0 && !x.empty()) {
         typename Container::key_type key = test::get_key<Container>(*x.begin());
         std::size_t count = x.count(key);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+        x.erase(x.begin());
+#else
         iterator pos = x.erase(x.begin());
-        --size;
         BOOST_TEST(pos == x.begin());
+#endif
+        --size;
         BOOST_TEST(x.count(key) == count - 1);
         BOOST_TEST(x.size() == size);
         if (++iterations % 20 == 0)
@@ -93,10 +95,15 @@ namespace erase_tests {
         typename Container::key_type key = test::get_key<Container>(*pos);
         std::size_t count = x.count(key);
         BOOST_TEST(count > 0);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+        x.erase(pos);
+        --size;
+#else
         BOOST_TEST(next == x.erase(pos));
         --size;
         if (size > 0)
           BOOST_TEST(index == 0 ? next == x.begin() : next == test::next(prev));
+#endif
         BOOST_TEST(x.count(key) == count - 1);
         if (x.count(key) != count - 1) {
           BOOST_LIGHTWEIGHT_TEST_OSTREAM << count << " => " << x.count(key)
@@ -185,7 +192,11 @@ namespace erase_tests {
       while (size > 0 && !x.empty()) {
         typename Container::key_type key = test::get_key<Container>(*x.begin());
         std::size_t count = x.count(key);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+        x.erase(x.begin());
+#else
         x.quick_erase(x.begin());
+#endif
         --size;
         BOOST_TEST(x.count(key) == count - 1);
         BOOST_TEST(x.size() == size);
@@ -216,7 +227,11 @@ namespace erase_tests {
         typename Container::key_type key = test::get_key<Container>(*pos);
         std::size_t count = x.count(key);
         BOOST_TEST(count > 0);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+        x.erase(pos);
+#else
         x.quick_erase(pos);
+#endif
         --size;
         if (size > 0)
           BOOST_TEST(index == 0 ? next == x.begin() : next == test::next(prev));
@@ -246,6 +261,20 @@ namespace erase_tests {
     BOOST_LIGHTWEIGHT_TEST_OSTREAM << "\n";
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::allocator1<test::object> >* test_map;
+
+  UNORDERED_TEST(
+    erase_tests1, ((test_set)(test_map))(
+                    (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::allocator1<test::object> >* test_set;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
@@ -255,13 +284,11 @@ namespace erase_tests {
   boost::unordered_multimap<test::object, test::object, test::hash,
     test::equal_to, test::allocator2<test::object> >* test_multimap;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
 
   UNORDERED_TEST(
     erase_tests1, ((test_set)(test_multiset)(test_map)(test_multimap))(
                     (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 
 RUN_TESTS()

test/unordered/find_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright (C) 2022 Christian Mazakas
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -133,6 +129,20 @@ namespace find_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator2<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash, test::equal_to,
+    test::allocator2<test::object> >* test_map;
+
+  UNORDERED_TEST(
+    find_tests1, ((test_set)(test_map))(
+                   (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::allocator2<test::object> >* test_set;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
@@ -142,16 +152,13 @@ namespace find_tests {
   boost::unordered_multimap<test::object, test::object, test::hash,
     test::equal_to, test::allocator1<test::object> >* test_multimap;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_TEST(
     find_tests1, ((test_set)(test_multiset)(test_map)(test_multimap))(
                    (default_generator)(generate_collisions)(limited_range)))
   UNORDERED_TEST(find_compatible_keys_test,
     ((test_set)(test_multiset)(test_map)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 
 RUN_TESTS()

test/unordered/fwd_map_test.cpp

@@ -1,14 +1,44 @@
 
 // Copyright 2008-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 // clang-format off
 #include "../helpers/prefix.hpp"
+#ifdef BOOST_UNORDERED_FOA_TESTS
+#include <boost/unordered/unordered_flat_map_fwd.hpp>
+#include <boost/unordered/detail/implementation.hpp>
+#else
 #include <boost/unordered/unordered_map_fwd.hpp>
+#endif
 #include "../helpers/postfix.hpp"
 // clang-format on
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+template <typename T>
+void call_swap(
+  boost::unordered_flat_map<T, T>& x, boost::unordered_flat_map<T, T>& y)
+{
+  swap(x, y);
+}
+
+template <typename T>
+bool call_equals(
+  boost::unordered_flat_map<T, T>& x, boost::unordered_flat_map<T, T>& y)
+{
+  return x == y;
+}
+
+template <typename T>
+bool call_not_equals(
+  boost::unordered_flat_map<T, T>& x, boost::unordered_flat_map<T, T>& y)
+{
+  return x != y;
+}
+
+#include <boost/unordered/unordered_flat_map.hpp>
+#else
 template <typename T>
 void call_swap(boost::unordered_map<T, T>& x, boost::unordered_map<T, T>& y)
 {
@@ -50,10 +80,15 @@ bool call_not_equals(
 }
 
 #include <boost/unordered_map.hpp>
+#endif
 #include "../helpers/test.hpp"
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_map<int, int> int_map;
+#else
 typedef boost::unordered_map<int, int> int_map;
 typedef boost::unordered_multimap<int, int> int_multimap;
+#endif
 
 UNORDERED_AUTO_TEST (use_map_fwd_declared_function) {
   int_map x, y;
@@ -71,11 +106,13 @@ UNORDERED_AUTO_TEST (use_map_fwd_declared_function) {
   BOOST_TEST(call_not_equals(x, y));
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 UNORDERED_AUTO_TEST (use_multimap_fwd_declared_function) {
   int_multimap x, y;
   call_swap(x, y);
   BOOST_TEST(call_equals(x, y));
   BOOST_TEST(!call_not_equals(x, y));
 }
+#endif
 
 RUN_TESTS()

test/unordered/fwd_set_test.cpp

@@ -1,11 +1,17 @@
 
 // Copyright 2008-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 // clang-format off
 #include "../helpers/prefix.hpp"
+#ifdef BOOST_UNORDERED_FOA_TESTS
+#include <boost/unordered/unordered_flat_set_fwd.hpp>
+#include <boost/unordered/detail/implementation.hpp>
+#else
 #include <boost/unordered/unordered_set_fwd.hpp>
+#endif
 #include "../helpers/postfix.hpp"
 // clang-format on
 
@@ -20,6 +26,31 @@ struct false_type
 
 false_type is_unordered_set_impl(void*);
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+template <class Value, class Hash, class Pred, class Alloc>
+true_type is_unordered_set_impl(
+  boost::unordered_flat_set<Value, Hash, Pred, Alloc>*);
+
+template <typename T>
+void call_swap(boost::unordered_flat_set<T>& x, boost::unordered_flat_set<T>& y)
+{
+  swap(x, y);
+}
+
+template <typename T>
+bool call_equals(
+  boost::unordered_flat_set<T>& x, boost::unordered_flat_set<T>& y)
+{
+  return x == y;
+}
+
+template <typename T>
+bool call_not_equals(
+  boost::unordered_flat_set<T>& x, boost::unordered_flat_set<T>& y)
+{
+  return x != y;
+}
+#else
 template <class Value, class Hash, class Pred, class Alloc>
 true_type is_unordered_set_impl(
   boost::unordered_set<Value, Hash, Pred, Alloc>*);
@@ -41,7 +72,9 @@ bool call_not_equals(boost::unordered_set<T>& x, boost::unordered_set<T>& y)
 {
   return x != y;
 }
+#endif
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 template <typename T>
 void call_swap(boost::unordered_multiset<T>& x, boost::unordered_multiset<T>& y)
 {
@@ -61,20 +94,29 @@ bool call_not_equals(
 {
   return x != y;
 }
+#endif
 
 #include "../helpers/test.hpp"
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_set<int> int_set;
+#else
 typedef boost::unordered_set<int> int_set;
 typedef boost::unordered_multiset<int> int_multiset;
+#endif
 
 UNORDERED_AUTO_TEST (use_fwd_declared_trait_without_definition) {
   BOOST_TEST(sizeof(is_unordered_set_impl((int_set*)0)) == sizeof(true_type));
 }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+#include <boost/unordered/unordered_flat_set.hpp>
+#else
 #include <boost/unordered_set.hpp>
+#endif
 
 UNORDERED_AUTO_TEST (use_fwd_declared_trait) {
-  boost::unordered_set<int> x;
+  int_set x;
   BOOST_TEST(sizeof(is_unordered_set_impl(&x)) == sizeof(true_type));
 
   BOOST_TEST(sizeof(is_unordered_set_impl((int*)0)) == sizeof(false_type));
@@ -96,11 +138,13 @@ UNORDERED_AUTO_TEST (use_set_fwd_declared_function) {
   BOOST_TEST(call_not_equals(x, y));
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 UNORDERED_AUTO_TEST (use_multiset_fwd_declared_function) {
   int_multiset x, y;
   call_swap(x, y);
   BOOST_TEST(call_equals(x, y));
   BOOST_TEST(!call_not_equals(x, y));
 }
+#endif
 
 RUN_TESTS()

test/unordered/incomplete_test.cpp

@@ -1,21 +1,21 @@
 
 // Copyright 2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_map.hpp>
-#include <boost/unordered_set.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include <utility>
 
 namespace x {
   struct D
   {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_map<D, D> x;
+#else
     boost::unordered_map<D, D> x;
+#endif
   };
 }
 
@@ -29,6 +29,17 @@ namespace incomplete_test {
 
   // Declare some instances
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_map<value, value, hash, equals,
+    allocator<std::pair<value const, value> > >
+    map;
+  typedef boost::unordered_flat_map<value, value, hash, equals,
+    allocator<std::pair<value const, value> > >
+    multimap;
+  typedef boost::unordered_flat_set<value, hash, equals, allocator<value> > set;
+  typedef boost::unordered_flat_set<value, hash, equals, allocator<value> >
+    multiset;
+#else
   typedef boost::unordered_map<value, value, hash, equals,
     allocator<std::pair<value const, value> > >
     map;
@@ -38,6 +49,7 @@ namespace incomplete_test {
   typedef boost::unordered_set<value, hash, equals, allocator<value> > set;
   typedef boost::unordered_multiset<value, hash, equals, allocator<value> >
     multiset;
+#endif
 
   // Now define the types which are stored as members, as they are needed for
   // declaring struct members.
@@ -76,7 +88,28 @@ namespace incomplete_test {
   //
   // Incomplete hash, equals and allocator aren't here supported at the
   // moment.
-
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  struct struct1
+  {
+    boost::unordered_flat_map<struct1, struct1, hash, equals,
+      allocator<std::pair<struct1 const, struct1> > >
+      x;
+  };
+  struct struct2
+  {
+    boost::unordered_flat_map<struct2, struct2, hash, equals,
+      allocator<std::pair<struct2 const, struct2> > >
+      x;
+  };
+  struct struct3
+  {
+    boost::unordered_flat_set<struct3, hash, equals, allocator<struct3> > x;
+  };
+  struct struct4
+  {
+    boost::unordered_flat_set<struct4, hash, equals, allocator<struct4> > x;
+  };
+#else
   struct struct1
   {
     boost::unordered_map<struct1, struct1, hash, equals,
@@ -97,7 +130,7 @@ namespace incomplete_test {
   {
     boost::unordered_multiset<struct4, hash, equals, allocator<struct4> > x;
   };
-
+#endif
   // Now define the value type.
 
   struct value

test/unordered/init_type_insert_tests.cpp

@@ -0,0 +1,244 @@
+
+// Copyright 2022 Christian Mazakas.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or move at http://www.boost.org/LICENSE_1_0.txt)
+
+#if !defined(BOOST_UNORDERED_FOA_TESTS)
+#error "This test is only for the FOA-style conatiners"
+#endif
+
+#include "../helpers/unordered.hpp"
+
+#include "../helpers/test.hpp"
+
+struct move_only
+{
+  int x_ = -1;
+
+  move_only() = default;
+  move_only(int x) : x_{x} {}
+  move_only(move_only const&) = delete;
+  move_only(move_only&&) = default;
+
+  friend bool operator==(move_only const& lhs, move_only const& rhs)
+  {
+    return lhs.x_ == rhs.x_;
+  }
+};
+
+namespace std{
+
+template <> struct hash<move_only>
+{
+  std::size_t operator()(move_only const& mo) const noexcept
+  {
+    return std::hash<int>()(mo.x_);
+  }
+};
+
+} // namespace std
+
+struct raii_tracker
+{
+  static unsigned move_constructs;
+  static unsigned copy_constructs;
+
+  int x_ = -1;
+
+  static void reset_counts()
+  {
+    move_constructs = 0;
+    copy_constructs = 0;
+  }
+
+  raii_tracker() {}
+  raii_tracker(int x) : x_{x} {}
+  raii_tracker(raii_tracker const& rhs) : x_{rhs.x_} { ++copy_constructs; }
+
+  raii_tracker(raii_tracker&& rhs) noexcept : x_{rhs.x_}
+  {
+    rhs.x_ = -1;
+
+    ++move_constructs;
+  }
+
+  friend bool operator==(raii_tracker const& lhs, raii_tracker const& rhs)
+  {
+    return lhs.x_ == rhs.x_;
+  }
+};
+
+namespace std{
+
+template <> struct hash<raii_tracker>
+{
+  std::size_t operator()(raii_tracker const& rt) const noexcept
+  {
+    return std::hash<int>()(rt.x_);
+  }
+};
+
+} // namespace std
+
+unsigned raii_tracker::move_constructs = 0;
+unsigned raii_tracker::copy_constructs = 0;
+
+static void test_move_only()
+{
+  int const v = 128;
+
+  boost::unordered_flat_map<move_only, int, std::hash<move_only> > map;
+
+  using init_type = decltype(map)::init_type;
+  static_assert(
+    std::is_same<decltype(std::make_pair(move_only(1), v)), init_type>::value,
+    "");
+
+  map.insert(std::make_pair(move_only(1), v));
+  map.insert({move_only(2), v});
+
+  BOOST_TEST_EQ(map.size(), 2u);
+
+  map.rehash(1024);
+  BOOST_TEST_GE(map.bucket_count(), 1024u);
+}
+
+static void test_insert_tracking()
+{
+  raii_tracker::reset_counts();
+
+  BOOST_TEST_EQ(raii_tracker::copy_constructs, 0u);
+  BOOST_TEST_EQ(raii_tracker::move_constructs, 0u);
+
+  boost::unordered_flat_map<raii_tracker, raii_tracker,
+    std::hash<raii_tracker> >
+    map;
+
+  {
+    std::pair<raii_tracker, raii_tracker> value{1, 2};
+
+    map.insert(value);
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 2u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 0u);
+  }
+
+  {
+    std::pair<raii_tracker, raii_tracker> value{2, 3};
+
+    map.insert(std::move(value));
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 2u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 2u);
+  }
+
+  {
+    std::pair<raii_tracker const, raii_tracker> value{3, 4};
+
+    map.insert(value);
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 4u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 2u);
+  }
+
+  {
+    std::pair<raii_tracker const, raii_tracker> value{4, 5};
+
+    map.insert(std::move(value));
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 3u);
+  }
+
+  {
+    map.insert(std::make_pair(5, 6));
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 5u);
+  }
+
+  {
+    map.insert({6, 7});
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 7u);
+  }
+
+  BOOST_TEST_EQ(map.size(), 6u);
+
+  map.rehash(1024);
+  BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+  BOOST_TEST_EQ(raii_tracker::move_constructs, 7u + 2u * map.size());
+}
+
+static void test_insert_hint_tracking()
+{
+  raii_tracker::reset_counts();
+
+  BOOST_TEST_EQ(raii_tracker::copy_constructs, 0u);
+  BOOST_TEST_EQ(raii_tracker::move_constructs, 0u);
+
+  boost::unordered_flat_map<raii_tracker, raii_tracker,
+    std::hash<raii_tracker> >
+    map;
+
+  {
+    std::pair<raii_tracker, raii_tracker> value{1, 2};
+
+    map.insert(map.begin(), value);
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 2u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 0u);
+  }
+
+  {
+    std::pair<raii_tracker, raii_tracker> value{2, 3};
+
+    map.insert(std::move(value));
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 2u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 2u);
+  }
+
+  {
+    std::pair<raii_tracker const, raii_tracker> value{3, 4};
+
+    map.insert(map.begin(), value);
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 4u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 2u);
+  }
+
+  {
+    std::pair<raii_tracker const, raii_tracker> value{4, 5};
+
+    map.insert(map.begin(), std::move(value));
+
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 3u);
+  }
+
+  {
+    map.insert(map.begin(), std::make_pair(5, 6));
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 5u);
+  }
+
+  {
+    map.insert(map.begin(), {6, 7});
+    BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+    BOOST_TEST_EQ(raii_tracker::move_constructs, 7u);
+  }
+
+  BOOST_TEST_EQ(map.size(), 6u);
+
+  map.rehash(1024);
+  BOOST_TEST_EQ(raii_tracker::copy_constructs, 5u);
+  BOOST_TEST_EQ(raii_tracker::move_constructs, 7u + 2u * map.size());
+}
+
+int main()
+{
+  test_move_only();
+  test_insert_tracking();
+  test_insert_hint_tracking();
+  return boost::report_errors();
+}

test/unordered/insert_hint_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2016 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../helpers/invariants.hpp"
@@ -17,6 +13,7 @@
 #include <set>
 
 namespace insert_hint {
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (insert_hint_empty) {
     typedef boost::unordered_multiset<int> container;
     container x;
@@ -90,9 +87,13 @@ namespace insert_hint {
       }
     }
   }
-
+#endif
   UNORDERED_AUTO_TEST (insert_hint_unique) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_set<int> container;
+#else
     typedef boost::unordered_set<int> container;
+#endif
     container x;
     x.insert(x.cbegin(), 10);
     BOOST_TEST_EQ(x.size(), 1u);
@@ -101,7 +102,11 @@ namespace insert_hint {
   }
 
   UNORDERED_AUTO_TEST (insert_hint_unique_single) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_set<int> container;
+#else
     typedef boost::unordered_set<int> container;
+#endif
     container x;
     x.insert(10);
 

test/unordered/insert_tests.cpp

@@ -1,16 +1,12 @@
 
 // Copyright 2006-2010 Daniel James.
+// Copyright (C) 2022 Christian Mazakas
 // 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)
 
 #if !defined(PIECEWISE_TEST_NAME)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -21,6 +17,8 @@
 #include "../helpers/input_iterator.hpp"
 #include "../helpers/helpers.hpp"
 
+#include <vector>
+
 namespace insert_tests {
 
   test::seed_t initialize_seed(243432);
@@ -678,6 +676,23 @@ namespace insert_tests {
     }
   }
 
+  template <class X> void set_tests(X*, test::random_generator)
+  {
+    // prove that our insert(iterator, iterator) implementation honors
+    // Cpp17EmplaceConstructible
+    //
+
+    X x;
+    std::vector<int> v;
+    v.reserve(1000);
+    for (unsigned i = 0; i < 1000; ++i) {
+      v.push_back(static_cast<int>(i));
+    }
+
+    x.insert(v.begin(), v.end());
+    BOOST_TEST_EQ(x.size(), 1000u);
+  }
+
   template <class X>
   void try_emplace_tests(X*, test::random_generator generator)
   {
@@ -870,6 +885,53 @@ namespace insert_tests {
     test::check_equivalent_keys(x);
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::movable, test::hash, test::equal_to,
+    std::allocator<test::movable> >* test_set_std_alloc;
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::movable, test::movable, test::hash,
+    test::equal_to, test::allocator2<test::movable> >* test_map;
+
+  UNORDERED_TEST(unique_insert_tests1,
+    ((test_set_std_alloc)(test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(
+    insert_tests2, ((test_set)(test_map))(
+                     (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(unique_emplace_tests1,
+    ((test_set_std_alloc)(test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(move_emplace_tests,
+    ((test_set_std_alloc)(test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(default_emplace_tests,
+    ((test_set_std_alloc)(test_set)(test_map))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(map_tests,
+    ((test_map))((default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(
+    map_tests2, ((test_map))((default_generator)(generate_collisions)))
+
+  UNORDERED_TEST(map_insert_range_test1,
+    ((test_map))((default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(map_insert_range_test2,
+    ((test_map))((default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(
+    set_tests, ((test_set_std_alloc)(test_set))((default_generator)))
+#else
   boost::unordered_set<test::movable, test::hash, test::equal_to,
     std::allocator<test::movable> >* test_set_std_alloc;
   boost::unordered_multimap<test::object, test::object, test::hash,
@@ -884,10 +946,6 @@ namespace insert_tests {
   boost::unordered_multimap<test::object, test::object, test::hash,
     test::equal_to, test::allocator1<test::object> >* test_multimap;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_TEST(unique_insert_tests1,
     ((test_set_std_alloc)(test_set)(test_map))(
       (default_generator)(generate_collisions)(limited_range)))
@@ -897,8 +955,8 @@ namespace insert_tests {
       (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(insert_tests2,
-    ((test_multimap_std_alloc)(test_set)(test_multiset)(test_map)(
-      test_multimap))((default_generator)(generate_collisions)(limited_range)))
+    ((test_multimap_std_alloc)(test_set)(test_multiset)(test_map)(test_multimap))(
+      (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(unique_emplace_tests1,
     ((test_set_std_alloc)(test_set)(test_map))(
@@ -909,13 +967,11 @@ namespace insert_tests {
       (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(move_emplace_tests,
-    ((test_set_std_alloc)(test_multimap_std_alloc)(test_set)(test_map)(
-      test_multiset)(test_multimap))(
+    ((test_set_std_alloc)(test_multimap_std_alloc)(test_set)(test_map)(test_multiset)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(default_emplace_tests,
-    ((test_set_std_alloc)(test_multimap_std_alloc)(test_set)(test_map)(
-      test_multiset)(test_multimap))(
+    ((test_set_std_alloc)(test_multimap_std_alloc)(test_set)(test_map)(test_multiset)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
 
   UNORDERED_TEST(map_tests,
@@ -932,6 +988,10 @@ namespace insert_tests {
     ((test_multimap_std_alloc)(test_map)(test_multimap))(
       (default_generator)(generate_collisions)(limited_range)))
 
+  UNORDERED_TEST(
+    set_tests, ((test_set_std_alloc)(test_set)(test_multiset))((default_generator)))
+#endif
+
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 
   struct initialize_from_two_ints
@@ -950,13 +1010,21 @@ namespace insert_tests {
   };
 
   UNORDERED_AUTO_TEST (insert_initializer_list_set) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> set;
+#else
     boost::unordered_set<int> set;
+#endif
     set.insert({1, 2, 3, 1});
     BOOST_TEST_EQ(set.size(), 3u);
     BOOST_TEST(set.find(1) != set.end());
     BOOST_TEST(set.find(4) == set.end());
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<initialize_from_two_ints> set2;
+#else
     boost::unordered_set<initialize_from_two_ints> set2;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 5))
     set2.insert({{1, 2}});
@@ -985,6 +1053,7 @@ namespace insert_tests {
     BOOST_TEST(set2.find({8, 7}) == set2.end());
   }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 #if !BOOST_WORKAROUND(BOOST_MSVC, == 1800)
 
   UNORDERED_AUTO_TEST (insert_initializer_list_multiset) {
@@ -1002,16 +1071,22 @@ namespace insert_tests {
     BOOST_TEST_EQ(multiset.count("c"), 0u);
   }
 
+#endif
 #endif
 
   UNORDERED_AUTO_TEST (insert_initializer_list_map) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<std::string, std::string> map;
+#else
     boost::unordered_map<std::string, std::string> map;
+  #endif
     // map.insert({});
     BOOST_TEST(map.empty());
     map.insert({{"a", "b"}, {"a", "b"}, {"d", ""}});
     BOOST_TEST_EQ(map.size(), 2u);
   }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (insert_initializer_list_multimap) {
     boost::unordered_multimap<std::string, std::string> multimap;
     // multimap.insert({});
@@ -1020,6 +1095,7 @@ namespace insert_tests {
     BOOST_TEST_EQ(multimap.size(), 3u);
     BOOST_TEST_EQ(multimap.count("a"), 2u);
   }
+#endif
 
 #endif
 
@@ -1050,10 +1126,18 @@ namespace insert_tests {
 
   UNORDERED_AUTO_TEST (map_emplace_test) {
     {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      boost::unordered_flat_map<int, overloaded_constructor, test::hash,
+        test::equal_to,
+        test::allocator1<std::pair<int const, overloaded_constructor> > >
+        x;
+#else
+
       boost::unordered_map<int, overloaded_constructor, test::hash,
         test::equal_to,
         test::allocator1<std::pair<int const, overloaded_constructor> > >
         x;
+#endif
 
 #if !BOOST_UNORDERED_SUN_WORKAROUNDS1
       x.emplace();
@@ -1070,6 +1154,7 @@ namespace insert_tests {
         x.find(5) != x.end() && x.find(5)->second == overloaded_constructor());
     }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
     {
       boost::unordered_multimap<int, overloaded_constructor, test::hash,
         test::equal_to,
@@ -1086,11 +1171,17 @@ namespace insert_tests {
       BOOST_TEST(
         x.find(2) != x.end() && x.find(2)->second == overloaded_constructor(3));
     }
+#endif
   }
 
   UNORDERED_AUTO_TEST (set_emplace_test) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<overloaded_constructor> x;
+    overloaded_constructor check;
+#else
     boost::unordered_set<overloaded_constructor> x;
     overloaded_constructor check;
+#endif
 
 #if !BOOST_UNORDERED_SUN_WORKAROUNDS1
     x.emplace();
@@ -1136,6 +1227,7 @@ namespace insert_tests {
     }
   };
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (map_emplace_test2) {
     // Emulating piecewise construction with boost::tuple bypasses the
     // allocator's construct method, but still uses test destroy method.
@@ -1259,10 +1351,13 @@ namespace insert_tests {
       std::make_pair(overloaded_constructor(1), overloaded_constructor(2, 3));
     BOOST_TEST(x.find(check) != x.end() && *x.find(check) == check);
   }
+#endif
 
 // Use the preprocessor to generate tests using different combinations of
 // boost/std piecewise_construct_t/tuple.
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
+
 #define PIECEWISE_TEST_NAME boost_tuple_piecewise_tests
 #define PIECEWISE_NAMESPACE boost::unordered
 #define TUPLE_NAMESPACE boost
@@ -1289,6 +1384,8 @@ namespace insert_tests {
 
 #endif
 
+#endif
+
 #if !defined(BOOST_NO_CXX11_HDR_TUPLE) &&                                      \
   BOOST_UNORDERED_HAVE_PIECEWISE_CONSTRUCT
 
@@ -1311,12 +1408,21 @@ UNORDERED_AUTO_TEST (PIECEWISE_TEST_NAME) {
 #endif
 
   {
+#if defined(BOOST_UNORDERED_FOA_TESTS)
+    boost::unordered_flat_map<overloaded_constructor, overloaded_constructor,
+      boost::hash<overloaded_constructor>,
+      std::equal_to<overloaded_constructor>,
+      test::allocator1<
+        std::pair<overloaded_constructor const, overloaded_constructor> > >
+      x;
+#else
     boost::unordered_map<overloaded_constructor, overloaded_constructor,
       boost::hash<overloaded_constructor>,
       std::equal_to<overloaded_constructor>,
       test::allocator1<
         std::pair<overloaded_constructor const, overloaded_constructor> > >
       x;
+#endif
 
     x.emplace(PIECEWISE_NAMESPACE::piecewise_construct,
       TUPLE_NAMESPACE::make_tuple(), TUPLE_NAMESPACE::make_tuple());
@@ -1360,6 +1466,7 @@ UNORDERED_AUTO_TEST (PIECEWISE_TEST_NAME) {
                x.find(overloaded_constructor(2, 3))->second ==
                  overloaded_constructor(4, 5, 6));
   }
+#ifndef BOOST_UNORDERED_FOA_TESTS
   {
     boost::unordered_multimap<overloaded_constructor, overloaded_constructor,
       boost::hash<overloaded_constructor>,
@@ -1393,6 +1500,7 @@ UNORDERED_AUTO_TEST (PIECEWISE_TEST_NAME) {
                x.find(overloaded_constructor(9, 3, 1))->second ==
                  overloaded_constructor(10));
   }
+#endif
 }
 
 UNORDERED_AUTO_TEST (BOOST_PP_CAT(PIECEWISE_TEST_NAME, 2)) {
@@ -1400,9 +1508,15 @@ UNORDERED_AUTO_TEST (BOOST_PP_CAT(PIECEWISE_TEST_NAME, 2)) {
   test::detail::disable_construction_tracking _scoped;
 #endif
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<
+    std::pair<overloaded_constructor, overloaded_constructor> >
+    x;
+#else
   boost::unordered_set<
     std::pair<overloaded_constructor, overloaded_constructor> >
     x;
+#endif
   std::pair<overloaded_constructor, overloaded_constructor> check;
 
   x.emplace(PIECEWISE_NAMESPACE::piecewise_construct,

test/unordered/link_test_1.cpp

@@ -1,15 +1,24 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void foo(boost::unordered_flat_set<int>&, boost::unordered_flat_map<int, int>&);
+
+int main()
+{
+  boost::unordered_flat_set<int> x1;
+  boost::unordered_flat_map<int, int> x2;
+
+  foo(x1, x2);
+
+  return 0;
+}
+#else
 void foo(boost::unordered_set<int>&, boost::unordered_map<int, int>&,
   boost::unordered_multiset<int>&, boost::unordered_multimap<int, int>&);
 
@@ -24,3 +33,4 @@ int main()
 
   return 0;
 }
+#endif

test/unordered/link_test_2.cpp

@@ -1,15 +1,27 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void foo(
+  boost::unordered_flat_set<int>& x1, boost::unordered_flat_map<int, int>& x2)
+{
+#if BOOST_WORKAROUND(BOOST_CODEGEARC, BOOST_TESTED_AT(0x0613))
+  struct dummy
+  {
+    boost::unordered_flat_set<int> x1;
+    boost::unordered_flat_map<int, int> x2;
+  };
+#endif
+
+  x1.insert(1);
+  x2[2] = 2;
+}
+#else
 void foo(boost::unordered_set<int>& x1, boost::unordered_map<int, int>& x2,
   boost::unordered_multiset<int>& x3, boost::unordered_multimap<int, int>& x4)
 {
@@ -28,3 +40,4 @@ void foo(boost::unordered_set<int>& x1, boost::unordered_map<int, int>& x2,
   x3.insert(3);
   x4.insert(std::make_pair(4, 5));
 }
+#endif

test/unordered/load_factor_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include <boost/limits.hpp>
@@ -26,7 +22,17 @@ namespace load_factor_tests {
   template <class X> void set_load_factor_tests(X*)
   {
     X x;
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST(x.max_load_factor() == boost::unordered::detail::foa::mlf);
+    BOOST_TEST(x.load_factor() == 0);
 
+    // A valid implementation could fail these tests, but I think they're
+    // reasonable.
+    x.max_load_factor(2.0);
+    BOOST_TEST(x.max_load_factor() == boost::unordered::detail::foa::mlf);
+    x.max_load_factor(0.5);
+    BOOST_TEST(x.max_load_factor() == boost::unordered::detail::foa::mlf);
+#else
     BOOST_TEST(x.max_load_factor() == 1.0);
     BOOST_TEST(x.load_factor() == 0);
 
@@ -36,6 +42,7 @@ namespace load_factor_tests {
     BOOST_TEST(x.max_load_factor() == 2.0);
     x.max_load_factor(0.5);
     BOOST_TEST(x.max_load_factor() == 0.5);
+#endif
   }
 
   template <class X>
@@ -72,21 +79,32 @@ namespace load_factor_tests {
       insert_test(ptr, std::numeric_limits<float>::infinity(), generator);
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int>* int_set_ptr;
+  boost::unordered_flat_map<int, int>* int_map_ptr;
+
+  UNORDERED_TEST(set_load_factor_tests, ((int_set_ptr)(int_map_ptr)))
+
+  UNORDERED_TEST(load_factor_insert_tests,
+    ((int_set_ptr)(int_map_ptr))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_set<int>* int_set_ptr;
   boost::unordered_multiset<int>* int_multiset_ptr;
   boost::unordered_map<int, int>* int_map_ptr;
   boost::unordered_multimap<int, int>* int_multimap_ptr;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_TEST(set_load_factor_tests,
     ((int_set_ptr)(int_multiset_ptr)(int_map_ptr)(int_multimap_ptr)))
 
   UNORDERED_TEST(load_factor_insert_tests,
     ((int_set_ptr)(int_multiset_ptr)(int_map_ptr)(int_multimap_ptr))(
       (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 
 RUN_TESTS()

test/unordered/merge_tests.cpp

@@ -1,12 +1,10 @@
 
 // Copyright 2016 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-#include "../helpers/postfix.hpp"
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_map.hpp>
-#include <boost/unordered_set.hpp>
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/count.hpp"
 #include "../helpers/helpers.hpp"
@@ -19,8 +17,13 @@
 namespace merge_tests {
 
   UNORDERED_AUTO_TEST (merge_set) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    boost::unordered_flat_set<int> x;
+    boost::unordered_flat_set<int> y;
+#else
     boost::unordered_set<int> x;
     boost::unordered_set<int> y;
+#endif
 
     x.merge(y);
     BOOST_TEST(x.empty());
@@ -57,6 +60,7 @@ namespace merge_tests {
     test::check_equivalent_keys(y);
   }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   UNORDERED_AUTO_TEST (merge_multiset) {
     boost::unordered_multiset<int> x;
     boost::unordered_multiset<int> y;
@@ -134,6 +138,7 @@ namespace merge_tests {
     test::check_equivalent_keys(x);
     test::check_equivalent_keys(y);
   }
+#endif
 
   template <class X1, class X2>
   void merge_empty_test(X1*, X2*, test::random_generator generator)
@@ -228,6 +233,82 @@ namespace merge_tests {
     test::check_equivalent_keys(x2);
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<test::movable, test::hash, test::equal_to,
+    std::allocator<test::movable> >* test_set_std_alloc;
+
+
+  boost::unordered_flat_map<test::object, test::object, test::hash, test::equal_to,
+    std::allocator<test::object> >* test_map_std_alloc;
+
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+
+
+  boost::unordered_flat_map<test::movable, test::movable, test::hash, test::equal_to,
+    test::allocator2<test::movable> >* test_map;
+
+  // clang-format off
+UNORDERED_TEST(merge_empty_test,
+    ((test_set_std_alloc))
+    ((test_set_std_alloc))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_empty_test,
+    ((test_map_std_alloc))
+    ((test_map_std_alloc))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_empty_test,
+    ((test_set))
+    ((test_set))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_empty_test,
+    ((test_map))
+    ((test_map))
+    ((default_generator)(generate_collisions)))
+
+UNORDERED_TEST(merge_into_empty_test,
+    ((test_set_std_alloc))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_empty_test,
+    ((test_map_std_alloc))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_empty_test,
+    ((test_set))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_empty_test,
+    ((test_map))
+    ((default_generator)(generate_collisions)))
+
+UNORDERED_TEST(merge_into_unique_keys_test,
+    ((test_set_std_alloc))
+    ((test_set_std_alloc))
+    ((0)(1)(2))
+    ((0)(1)(2))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_unique_keys_test,
+    ((test_map_std_alloc))
+    ((test_map_std_alloc))
+    ((0)(1)(2))
+    ((0)(1)(2))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_unique_keys_test,
+    ((test_set))
+    ((test_set))
+    ((0)(1)(2))
+    ((0)(1)(2))
+    ((default_generator)(generate_collisions)))
+UNORDERED_TEST(merge_into_unique_keys_test,
+    ((test_map))
+    ((test_map))
+    ((0)(1)(2))
+    ((0)(1)(2))
+    ((default_generator)(generate_collisions)))
+  // clang-format on
+#else
   boost::unordered_set<test::movable, test::hash, test::equal_to,
     std::allocator<test::movable> >* test_set_std_alloc;
   boost::unordered_multiset<test::movable, test::hash, test::equal_to,
@@ -248,9 +329,6 @@ namespace merge_tests {
   boost::unordered_multimap<test::movable, test::movable, test::hash,
     test::equal_to, test::allocator2<test::movable> >* test_multimap;
 
-  using test::default_generator;
-  using test::generate_collisions;
-
   // clang-format off
 UNORDERED_TEST(merge_empty_test,
     ((test_set_std_alloc)(test_multiset_std_alloc))
@@ -332,6 +410,8 @@ UNORDERED_TEST(merge_into_equiv_keys_test,
     ((0)(1)(2))
     ((default_generator)(generate_collisions)))
   // clang-format on
+#endif
+
 }
 
 RUN_TESTS()

test/unordered/move_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2008-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or move at http://www.boost.org/LICENSE_1_0.txt)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../objects/test.hpp"
@@ -18,6 +14,9 @@
 #include "../helpers/equivalent.hpp"
 #include "../helpers/invariants.hpp"
 
+#include <boost/core/ignore_unused.hpp>
+#include <iterator>
+
 #if defined(BOOST_MSVC)
 #pragma warning(disable : 4127) // conditional expression is constant
 #endif
@@ -68,8 +67,16 @@ namespace move_tests {
       BOOST_TEST(test::equivalent(y.hash_function(), hf));
       BOOST_TEST(test::equivalent(y.key_eq(), eq));
       BOOST_TEST(test::equivalent(y.get_allocator(), al));
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 1.0);
+#endif
       test::check_equivalent_keys(y);
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+#endif
     }
 
     {
@@ -87,7 +94,7 @@ namespace move_tests {
   }
 
   template <class T>
-  void move_assign_tests1(T*, test::random_generator const& generator)
+  void move_assign_tests1(T* p, test::random_generator const& generator)
   {
     {
       test::check_instances check_;
@@ -98,6 +105,19 @@ namespace move_tests {
       y = create(v, count);
 #if BOOST_UNORDERED_TEST_MOVING && defined(BOOST_HAS_NRVO)
       BOOST_TEST(count == test::global_object_count);
+#endif
+      test::check_container(y, v);
+      test::check_equivalent_keys(y);
+    }
+
+    {
+      test::random_values<T> v;
+
+      T y;
+      y = empty(p);
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
 #endif
       test::check_container(y, v);
       test::check_equivalent_keys(y);
@@ -126,7 +146,11 @@ namespace move_tests {
       BOOST_TEST(test::equivalent(y.hash_function(), hf));
       BOOST_TEST(test::equivalent(y.key_eq(), eq));
       BOOST_TEST(test::equivalent(y.get_allocator(), al));
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 0.5); // Not necessarily required.
+#endif
       test::check_equivalent_keys(y);
     }
 
@@ -142,7 +166,11 @@ namespace move_tests {
       BOOST_TEST(test::equivalent(y.hash_function(), hf));
       BOOST_TEST(test::equivalent(y.key_eq(), eq));
       BOOST_TEST(test::equivalent(y.get_allocator(), al2));
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 2.0); // Not necessarily required.
+#endif
       test::check_equivalent_keys(y);
     }
 
@@ -172,7 +200,11 @@ namespace move_tests {
       BOOST_TEST(test::equivalent(y.hash_function(), hf));
       BOOST_TEST(test::equivalent(y.key_eq(), eq));
       BOOST_TEST(test::equivalent(y.get_allocator(), al));
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 1.0); // Not necessarily required.
+#endif
       test::check_equivalent_keys(y);
     }
   }
@@ -195,7 +227,11 @@ namespace move_tests {
       BOOST_TEST(y.empty());
       test::check_container(y, v2);
       test::check_equivalent_keys(y);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 2.0);
+#endif
 
 #if defined(BOOST_HAS_NRVO)
       if (BOOST_UNORDERED_TEST_MOVING
@@ -220,7 +256,11 @@ namespace move_tests {
 #endif
       test::check_container(y, v);
       test::check_equivalent_keys(y);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 0.5);
+#endif
 
 #if defined(BOOST_HAS_NRVO)
       if (BOOST_UNORDERED_TEST_MOVING
@@ -233,6 +273,36 @@ namespace move_tests {
 #endif
     }
 
+    {
+      test::random_values<T> v;
+      T y(0, hf, eq, al1);
+      T x(0, hf, eq, al2);
+      x.max_load_factor(0.25);
+
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+
+      y = boost::move(x);
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+#endif
+      test::check_container(y, v);
+      test::check_equivalent_keys(y);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
+      BOOST_TEST(y.max_load_factor() == 0.25);
+#endif
+
+      if (BOOST_UNORDERED_TEST_MOVING
+            ? (bool)allocator_type::is_propagate_on_move
+            : (bool)allocator_type::is_propagate_on_assign) {
+        BOOST_TEST(test::equivalent(y.get_allocator(), al2));
+      } else {
+        BOOST_TEST(test::equivalent(y.get_allocator(), al1));
+      }
+    }
+
     {
       test::check_instances check_;
 
@@ -250,7 +320,11 @@ namespace move_tests {
       }
       test::check_container(y, v);
       test::check_equivalent_keys(y);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 0.25);
+#endif
 
       if (BOOST_UNORDERED_TEST_MOVING
             ? (bool)allocator_type::is_propagate_on_move
@@ -286,7 +360,11 @@ namespace move_tests {
 
       test::check_container(y, v2);
       test::check_equivalent_keys(y);
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.max_load_factor() == 0.875);
+#else
       BOOST_TEST(y.max_load_factor() == 0.5);
+#endif
 
       if (BOOST_UNORDERED_TEST_MOVING
             ? (bool)allocator_type::is_propagate_on_move
@@ -298,17 +376,65 @@ namespace move_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    std::allocator<std::pair<test::object const, test::object> > >*
+    test_map_std_alloc;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator2<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >* test_map;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_move> >*
+    test_set_prop_move;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_map_prop_move;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_move> >*
+    test_set_no_prop_move;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_map_no_prop_move;
+
+  UNORDERED_TEST(move_construct_tests1,
+    ((test_map_std_alloc)(test_set)(test_map)(test_set_prop_move)(test_map_prop_move)(test_set_no_prop_move)(test_map_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(move_assign_tests1,
+    ((test_map_std_alloc)(test_set)(test_map)(test_set_prop_move)(test_map_prop_move)(test_set_no_prop_move)(test_map_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(move_construct_tests2,
+    ((test_set)(test_map)(test_set_prop_move)(test_map_prop_move)(test_set_no_prop_move)(test_map_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(move_assign_tests2,
+    ((test_set)(test_map)(test_set_prop_move)(test_map_prop_move)(test_set_no_prop_move)(test_map_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
-    std::allocator<test::object> >* test_map_std_alloc;
+    std::allocator<std::pair<test::object const, test::object> > >*
+    test_map_std_alloc;
 
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::allocator2<test::object> >* test_set;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
     test::allocator1<test::object> >* test_multiset;
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
-    test::allocator1<test::object> >* test_map;
+    test::allocator1<std::pair<test::object const, test::object> > >* test_map;
   boost::unordered_multimap<test::object, test::object, test::hash,
-    test::equal_to, test::allocator2<test::object> >* test_multimap;
+    test::equal_to,
+    test::allocator2<std::pair<test::object const, test::object> > >*
+    test_multimap;
 
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::cxx11_allocator<test::object, test::propagate_move> >*
@@ -317,11 +443,12 @@ namespace move_tests {
     test::cxx11_allocator<test::object, test::propagate_move> >*
     test_multiset_prop_move;
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
-    test::cxx11_allocator<test::object, test::propagate_move> >*
-    test_map_prop_move;
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_map_prop_move;
   boost::unordered_multimap<test::object, test::object, test::hash,
-    test::equal_to, test::cxx11_allocator<test::object, test::propagate_move> >*
-    test_multimap_prop_move;
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_multimap_prop_move;
 
   boost::unordered_set<test::object, test::hash, test::equal_to,
     test::cxx11_allocator<test::object, test::no_propagate_move> >*
@@ -330,16 +457,12 @@ namespace move_tests {
     test::cxx11_allocator<test::object, test::no_propagate_move> >*
     test_multiset_no_prop_move;
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
-    test::cxx11_allocator<test::object, test::no_propagate_move> >*
-    test_map_no_prop_move;
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_map_no_prop_move;
   boost::unordered_multimap<test::object, test::object, test::hash,
     test::equal_to,
-    test::cxx11_allocator<test::object, test::no_propagate_move> >*
-    test_multimap_no_prop_move;
-
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_multimap_no_prop_move;
 
   UNORDERED_TEST(move_construct_tests1,
     ((test_map_std_alloc)(test_set)(test_multiset)(test_map)(test_multimap)(
@@ -367,6 +490,7 @@ namespace move_tests {
       test_set_no_prop_move)(test_multiset_no_prop_move)(test_map_no_prop_move)(
       test_multimap_no_prop_move))(
       (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 
 RUN_TESTS()

test/unordered/noexcept_tests.cpp

@@ -1,16 +1,13 @@
 
 // Copyright 2013 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
+#include "../helpers/fwd.hpp"
 
 #if defined(BOOST_MSVC)
 #pragma warning(push)
@@ -201,6 +198,12 @@ namespace noexcept_tests {
 
   UNORDERED_AUTO_TEST (test_noexcept) {
     if (have_is_nothrow_move) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST((boost::is_nothrow_move_constructible<
+        boost::unordered_flat_set<int> >::value));
+      BOOST_TEST((boost::is_nothrow_move_constructible<
+        boost::unordered_flat_map<int, int> >::value));
+#else
       BOOST_TEST((boost::is_nothrow_move_constructible<
         boost::unordered_set<int> >::value));
       BOOST_TEST((boost::is_nothrow_move_constructible<
@@ -209,19 +212,35 @@ namespace noexcept_tests {
         boost::unordered_map<int, int> >::value));
       BOOST_TEST((boost::is_nothrow_move_constructible<
         boost::unordered_multimap<int, int> >::value));
+#endif
     }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST(
+      (!boost::is_nothrow_move_constructible<
+        boost::unordered_flat_set<int, hash_possible_exception> >::value));
+    BOOST_TEST(
+      (!boost::is_nothrow_move_constructible<boost::unordered_flat_set<int,
+          boost::hash<int>, equal_to_possible_exception> >::value));
+#else
     BOOST_TEST((!boost::is_nothrow_move_constructible<
                 boost::unordered_set<int, hash_possible_exception> >::value));
     BOOST_TEST(
       (!boost::is_nothrow_move_constructible<boost::unordered_multiset<int,
           boost::hash<int>, equal_to_possible_exception> >::value));
+#endif
   }
 
   UNORDERED_AUTO_TEST (test_nothrow_move_when_noexcept) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_set<int, hash_nothrow_move_construct,
+      equal_to_nothrow_move_construct>
+      throwing_set;
+#else
     typedef boost::unordered_set<int, hash_nothrow_move_construct,
       equal_to_nothrow_move_construct>
       throwing_set;
+#endif
 
     if (have_is_nothrow_move) {
       BOOST_TEST(boost::is_nothrow_move_constructible<throwing_set>::value);
@@ -247,42 +266,76 @@ namespace noexcept_tests {
     throwing_test_exception = false;
   }
 
-  UNORDERED_AUTO_TEST (test_nothrow_move_assign_when_noexcept) {
-    typedef boost::unordered_set<int, hash_nothrow_move_assign,
-      equal_to_nothrow_move_assign>
-      throwing_set;
+  template <class T>
+  void test_nothrow_move_assign_when_noexcept(T*, test::random_generator const&)
+  {
+    {
+      if (have_is_nothrow_move_assign) {
+        BOOST_TEST(boost::is_nothrow_move_assignable<T>::value);
+      }
 
-    if (have_is_nothrow_move_assign) {
-      BOOST_TEST(boost::is_nothrow_move_assignable<throwing_set>::value);
+      throwing_test_exception = false;
+
+      T x1;
+      T x2;
+      x1.insert(10);
+      x1.insert(50);
+      for (int i = 0; i < 100; ++i) {
+        x2.insert(i);
+      }
+
+      try {
+        throwing_test_exception = true;
+
+        x2 = boost::move(x1);
+        BOOST_TEST(x2.size() == 2);
+        BOOST_TEST(*x2.begin() == 10 || *x2.begin() == 50);
+        BOOST_TEST(have_is_nothrow_move_assign);
+      } catch (test_exception) {
+        BOOST_TEST(!have_is_nothrow_move_assign);
+      }
+
+      throwing_test_exception = false;
     }
 
-    throwing_test_exception = false;
+    {
+      if (have_is_nothrow_move_assign) {
+        BOOST_TEST(boost::is_nothrow_move_assignable<T>::value);
+      }
 
-    throwing_set x1;
-    throwing_set x2;
-    x1.insert(10);
-    x1.insert(50);
-    for (int i = 0; i < 100; ++i) {
-      x2.insert(i);
+      throwing_test_exception = false;
+
+      T x1;
+      T x2;
+      x1.insert(10);
+      x1.insert(50);
+      for (int i = 0; i < 100; ++i) {
+        x2.insert(i);
+      }
+
+      try {
+        throwing_test_exception = true;
+
+        x1 = boost::move(x2);
+        BOOST_TEST(x1.size() == 100);
+        BOOST_TEST(have_is_nothrow_move_assign);
+      } catch (test_exception) {
+        BOOST_TEST(!have_is_nothrow_move_assign);
+      }
+
+      throwing_test_exception = false;
     }
-
-    try {
-      throwing_test_exception = true;
-
-      x2 = boost::move(x1);
-      BOOST_TEST(x2.size() == 2);
-      BOOST_TEST(*x2.begin() == 10 || *x2.begin() == 50);
-      BOOST_TEST(have_is_nothrow_move_assign);
-    } catch (test_exception) {
-      BOOST_TEST(!have_is_nothrow_move_assign);
-    }
-
-    throwing_test_exception = false;
   }
 
   UNORDERED_AUTO_TEST (test_nothrow_swap_when_noexcept) {
+#if BOOST_UNORDERED_FOA_TESTS
+    typedef boost::unordered_flat_set<int, hash_nothrow_swap,
+      equal_to_nothrow_swap>
+      throwing_set;
+#else
     typedef boost::unordered_set<int, hash_nothrow_swap, equal_to_nothrow_swap>
       throwing_set;
+#endif
 
     if (have_is_nothrow_swap) {
       BOOST_TEST(boost::is_nothrow_swappable<throwing_set>::value);
@@ -318,4 +371,93 @@ namespace noexcept_tests {
 #pragma warning(pop)
 #endif
 
+template <class T> class allocator1
+{
+  BOOST_COPYABLE_AND_MOVABLE(allocator1)
+  allocator1 operator=(BOOST_COPY_ASSIGN_REF(allocator1));
+  allocator1 operator=(BOOST_RV_REF(allocator1));
+
+public:
+  typedef T value_type;
+
+  allocator1() {}
+  allocator1(allocator1 const&) {}
+
+  template <class U> allocator1(allocator1<U> const&) {}
+
+  T* allocate(std::size_t n)
+  {
+    noexcept_tests::test_throw("Allocate");
+    return static_cast<T*>(::operator new(n * sizeof(T)));
+  }
+
+  void deallocate(T* p, std::size_t) { ::operator delete(p); }
+
+  friend bool operator==(allocator1 const&, allocator1 const&) { return true; }
+  friend bool operator!=(allocator1 const&, allocator1 const&) { return false; }
+};
+
+template <class T> class allocator2
+{
+  BOOST_COPYABLE_AND_MOVABLE(allocator2)
+  allocator2 operator=(BOOST_COPY_ASSIGN_REF(allocator2));
+public:
+  typedef T value_type;
+  typedef boost::true_type propagate_on_container_move_assignment;
+
+  allocator2() {}
+  allocator2(allocator2 const&) {}
+
+  template <class U> allocator2(allocator2<U> const&) {}
+
+  allocator2& operator=(BOOST_RV_REF(allocator2)) { return *this; }
+
+  T* allocate(std::size_t n)
+  {
+    noexcept_tests::test_throw("Allocate");
+    return static_cast<T*>(::operator new(n * sizeof(T)));
+  }
+
+  void deallocate(T* p, std::size_t) { ::operator delete(p); }
+
+  friend bool operator==(allocator2 const&, allocator2 const&) { return true; }
+  friend bool operator!=(allocator2 const&, allocator2 const&) { return false; }
+};
+
+UNORDERED_AUTO_TEST (prelim_allocator_checks) {
+  BOOST_TEST(boost::allocator_is_always_equal<allocator1<int> >::type::value);
+  BOOST_TEST(!boost::allocator_propagate_on_container_move_assignment<
+             allocator1<int> >::type::value);
+
+  BOOST_TEST(boost::allocator_is_always_equal<allocator2<int> >::type::value);
+  BOOST_TEST(boost::allocator_propagate_on_container_move_assignment<
+             allocator2<int> >::type::value);
+}
+
+using test::default_generator;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+boost::unordered_flat_set<int, noexcept_tests::hash_nothrow_move_assign,
+  noexcept_tests::equal_to_nothrow_move_assign, allocator1<int> >*
+  throwing_set_alloc1;
+
+boost::unordered_flat_set<int, noexcept_tests::hash_nothrow_move_assign,
+  noexcept_tests::equal_to_nothrow_move_assign, allocator2<int> >*
+  throwing_set_alloc2;
+
+UNORDERED_TEST(test_nothrow_move_assign_when_noexcept,
+  ((throwing_set_alloc1)(throwing_set_alloc2))((default_generator)))
+#else
+boost::unordered_set<int, noexcept_tests::hash_nothrow_move_assign,
+  noexcept_tests::equal_to_nothrow_move_assign, allocator1<int> >*
+  throwing_set_alloc1;
+
+boost::unordered_set<int, noexcept_tests::hash_nothrow_move_assign,
+  noexcept_tests::equal_to_nothrow_move_assign, allocator2<int> >*
+  throwing_set_alloc2;
+
+UNORDERED_TEST(test_nothrow_move_assign_when_noexcept,
+  ((throwing_set_alloc1)(throwing_set_alloc2))((default_generator)))
+#endif
+
 RUN_TESTS()

test/unordered/post_move_tests.cpp

@@ -0,0 +1,666 @@
+
+// Copyright (C) 2022 Christian Mazakas
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or move at http://www.boost.org/LICENSE_1_0.txt)
+
+#include "../helpers/unordered.hpp"
+#include "../helpers/test.hpp"
+#include "../objects/test.hpp"
+#include "../objects/cxx11_allocator.hpp"
+#include "../helpers/random_values.hpp"
+#include "../helpers/tracker.hpp"
+#include "../helpers/equivalent.hpp"
+#include "../helpers/invariants.hpp"
+
+#include <boost/core/ignore_unused.hpp>
+#include <iterator>
+
+#if defined(BOOST_MSVC)
+#pragma warning(disable : 4127) // conditional expression is constant
+#endif
+
+namespace move_tests {
+  test::seed_t initialize_seed(98624);
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#define BOOST_UNORDERED_TEST_MOVING 1
+#else
+#define BOOST_UNORDERED_TEST_MOVING 0
+#endif
+
+  template <class T> T empty(T*) { return T(); }
+
+  template <class T>
+  T create(test::random_values<T> const& v, test::object_count& count)
+  {
+    T x(v.begin(), v.end());
+    count = test::global_object_count;
+    return x;
+  }
+
+  template <class T>
+  T create(test::random_values<T> const& v, test::object_count& count,
+    typename T::hasher hf, typename T::key_equal eq,
+    typename T::allocator_type al, float mlf)
+  {
+    T x(0, hf, eq, al);
+    x.max_load_factor(mlf);
+    x.insert(v.begin(), v.end());
+    count = test::global_object_count;
+    return x;
+  }
+
+  template <class T> T const& get_key(T const& t) { return t; }
+
+  template <class K, class V> K const& get_key(std::pair<K const, V> const& kv)
+  {
+    return kv.first;
+  }
+
+  template <class T> T const& get_value(T const& t) { return t; }
+
+  template <class K, class V> K const& get_value(std::pair<K const, V> const& kv)
+  {
+    return kv.second;
+  }
+
+  template <class T>
+  static void insert_range(T& y, test::random_values<T> const& v)
+  {
+    y.insert(v.begin(), v.end());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void insert_single(T& y, test::random_values<T> const& v)
+  {
+    y.insert(*v.begin());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void insert_single_hint(T& y, test::random_values<T> const& v)
+  {
+    y.insert(y.end(), *v.begin());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> struct insert_or_assign_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct insert_or_assign_invoker<
+    boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      typedef typename boost::unordered_map<Key, T, Hash, KeyEqual,
+        Allocator>::size_type size_type;
+
+      y.insert_or_assign(get_key(*v.begin()), get_value(*v.begin()));
+      BOOST_TEST_EQ(
+        y.size(), static_cast<size_type>(std::distance(y.begin(), y.end())));
+    }
+  };
+
+  template <class T>
+  static void insert_or_assign(T& y, test::random_values<T> const& v)
+  {
+    insert_or_assign_invoker<T>()(y, v);
+  }
+
+  template <class T> struct insert_or_assign_hint_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct insert_or_assign_hint_invoker<
+    boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      typedef typename boost::unordered_map<Key, T, Hash, KeyEqual,
+        Allocator>::size_type size_type;
+      y.insert_or_assign(y.end(), get_key(*v.begin()), get_value(*v.begin()));
+      BOOST_TEST_EQ(
+        y.size(), static_cast<size_type>(std::distance(y.begin(), y.end())));
+    }
+  };
+
+  template <class T>
+  static void insert_or_assign_hint(T& y, test::random_values<T> const& v)
+  {
+    insert_or_assign_hint_invoker<T>()(y, v);
+  }
+
+  template <class T> struct try_emplace_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct try_emplace_invoker<
+    boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      typedef typename boost::unordered_map<Key, T, Hash, KeyEqual,
+        Allocator>::size_type size_type;
+      y.try_emplace(get_key(*v.begin()), get_value(*v.begin()));
+      BOOST_TEST_EQ(
+        y.size(), static_cast<size_type>(std::distance(y.begin(), y.end())));
+    }
+  };
+
+  template <class T>
+  static void try_emplace(T& y, test::random_values<T> const& v)
+  {
+    try_emplace_invoker<T>()(y, v);
+  }
+
+  template <class T> struct try_emplace_hint_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct try_emplace_hint_invoker<
+    boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      typedef typename boost::unordered_map<Key, T, Hash, KeyEqual,
+        Allocator>::size_type size_type;
+      y.try_emplace(y.end(), get_key(*v.begin()), get_value(*v.begin()));
+      BOOST_TEST_EQ(
+        y.size(), static_cast<size_type>(std::distance(y.begin(), y.end())));
+    }
+  };
+
+  template <class T>
+  static void try_emplace_hint(T& y, test::random_values<T> const& v)
+  {
+    try_emplace_hint_invoker<T>()(y, v);
+  }
+
+  template <class T> struct at_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct at_invoker<boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      BOOST_TRY { y.at(get_key(*v.begin())); }
+      BOOST_CATCH(...) {}
+      BOOST_CATCH_END
+    }
+  };
+
+  template <class T> static void at(T& y, test::random_values<T> const& v)
+  {
+    at_invoker<T>()(y, v);
+  }
+
+  template <class T> struct index_operator_invoker
+  {
+    void operator()(T&, test::random_values<T> const&) {}
+  };
+
+  template <class Key, class T, class Hash, class KeyEqual, class Allocator>
+  struct index_operator_invoker<
+    boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> >
+  {
+    void operator()(boost::unordered_map<Key, T, Hash, KeyEqual, Allocator>& y,
+      test::random_values<
+        boost::unordered_map<Key, T, Hash, KeyEqual, Allocator> > const& v)
+    {
+      typedef typename boost::unordered_map<Key, T, Hash, KeyEqual,
+        Allocator>::size_type size_type;
+      y[get_key(*v.begin())] = get_value(*v.begin());
+      BOOST_TEST_EQ(
+        y.size(), static_cast<size_type>(std::distance(y.begin(), y.end())));
+    }
+  };
+
+  template <class T>
+  static void index_operator(T& y, test::random_values<T> const& v)
+  {
+    index_operator_invoker<T>()(y, v);
+  }
+
+  template <class T> static void clear(T& y, test::random_values<T> const&)
+  {
+    y.clear();
+    BOOST_TEST(y.empty());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void capacity(T& y, test::random_values<T> const&)
+  {
+    (void)y.empty();
+    (void)y.size();
+    (void)y.max_size();
+    (void)y.load_factor();
+    (void)y.max_load_factor();
+    (void)y.hash_function();
+    (void)y.key_eq();
+    (void)y.get_allocator();
+  }
+
+  template <class T> static void iterators(T& y, test::random_values<T> const&)
+  {
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void erase_range(T& y, test::random_values<T> const&)
+  {
+    y.erase(y.begin(), y.end());
+    BOOST_TEST(y.empty());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void erase_key(T& y, test::random_values<T> const& v)
+  {
+    y.erase(get_key(*v.begin()));
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void lookup(T& y, test::random_values<T> const& v)
+  {
+    (void)y.count(get_key(*v.begin()));
+    (void)y.find(get_key(*v.begin()));
+    (void)y.contains(get_key(*v.begin()));
+    (void)y.equal_range(get_key(*v.begin()));
+  }
+
+  template <class T> static void reserve(T& y, test::random_values<T> const&)
+  {
+    y.reserve(1337);
+    BOOST_TEST_GT(y.bucket_count(), 1337u);
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void copy_assignment(T& y, test::random_values<T> const& v)
+  {
+    T x(v.begin(), v.end());
+    y = x;
+    BOOST_TEST_EQ(y.size(), x.size());
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void move_assignment(T& y, test::random_values<T> const& v)
+  {
+    T x(v.begin(), v.end());
+    std::size_t const size = x.size();
+    y = boost::move(x);
+    BOOST_TEST_GE(y.size(), size);
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void equal(T& y, test::random_values<T> const& v)
+  {
+    T x(v.begin(), v.end());
+    (void)(y == x);
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void extract(T& y, test::random_values<T> const& v)
+  {
+    (void)y.extract(get_key(*v.begin()));
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void merge(T& y, test::random_values<T> const& v)
+  {
+    T x(v.begin(), v.end());
+    if (y.get_allocator() == x.get_allocator()) {
+      y.merge(x);
+    }
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class X> bool pred(X const&) { return true; }
+
+  template <class T>
+  static void erase_with_pred(T& y, test::random_values<T> const&)
+  {
+    erase_if(y, pred<typename T::value_type>);
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T>
+  static void container_swap(T& y, test::random_values<T> const& v)
+  {
+    T x(v.begin(), v.end());
+    if (boost::allocator_propagate_on_container_swap<
+          typename T::allocator_type>::type::value ||
+        x.get_allocator() == y.get_allocator()) {
+      y.swap(x);
+    }
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+  }
+
+  template <class T> static void buckets(T& y, test::random_values<T> const& v)
+  {
+    (void)y.begin(0);
+    (void)y.end(0);
+    (void)y.bucket_count();
+    (void)y.max_bucket_count();
+    (void)y.bucket_size(0);
+    (void)y.bucket(get_key(*v.begin()));
+  }
+
+  template <class T>
+  static void double_move_construct(T& y, test::random_values<T> const&)
+  {
+    T x = boost::move(y);
+    x.clear();
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+    BOOST_TEST_EQ(x.size(),
+      static_cast<typename T::size_type>(std::distance(x.begin(), x.end())));
+  }
+
+  template <class T>
+  static void double_move_assign(T& y, test::random_values<T> const&)
+  {
+    T x;
+    x = boost::move(y);
+    x.clear();
+    BOOST_TEST_EQ(y.size(),
+      static_cast<typename T::size_type>(std::distance(y.begin(), y.end())));
+    BOOST_TEST_EQ(x.size(),
+      static_cast<typename T::size_type>(std::distance(x.begin(), x.end())));
+  }
+
+  template <class T>
+  static void post_move_tests(T* ptr, test::random_generator const& generator)
+  {
+    // clang-format off
+    void (*fps[])(T&, test::random_values<T> const&) = {
+      insert_range<T>,
+      insert_single<T>,
+      insert_single_hint<T>,
+      insert_or_assign<T>,
+      insert_or_assign_hint<T>,
+      try_emplace<T>,
+      try_emplace_hint<T>,
+      at<T>,
+      index_operator<T>,
+      clear<T>,
+      capacity<T>,
+      iterators<T>,
+      erase_range<T>,
+      erase_key<T>,
+      lookup<T>,
+      reserve<T>,
+      copy_assignment<T>,
+      move_assignment<T>,
+      equal<T>,
+      #ifndef BOOST_UNORDERED_FOA_TESTS
+      extract<T>,
+      buckets<T>,
+      #endif
+      merge<T>,
+      erase_with_pred<T>,
+      container_swap<T>,
+      double_move_construct<T>,
+      double_move_assign<T>
+    };
+    // clang-format on
+
+    std::size_t const len = (sizeof(fps) / sizeof(*(fps)));
+
+    for (std::size_t i = 0; i < len; ++i) {
+      test::check_instances check_;
+
+      test::random_values<T> const v(1000, generator);
+      test::object_count count;
+      T y(create(v, count));
+
+      unsigned num_allocs = test::detail::tracker.count_allocations;
+      (void)num_allocs;
+
+      T x(boost::move(y));
+
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+      BOOST_TEST(y.empty());
+      BOOST_TEST(y.begin() == y.end());
+      BOOST_TEST_EQ(y.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, num_allocs);
+#endif
+
+      fps[i](y, v);
+
+      test::check_container(x, v);
+      test::check_equivalent_keys(x);
+    }
+
+    for (std::size_t i = 0; i < len; ++i) {
+      typename T::hasher hf(1);
+      typename T::key_equal eq(1);
+      typename T::allocator_type al1(1);
+      typename T::allocator_type al2(2);
+
+      test::check_instances check_;
+
+      test::random_values<T> v(1000, generator);
+      test::object_count count;
+      T y(v.begin(), v.end(), 0, hf, eq, al1);
+      T x(boost::move(y), al2);
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      BOOST_TEST(y.empty());
+      BOOST_TEST(y.begin() == y.end());
+#else
+      BOOST_TEST_NOT(y.empty());
+      BOOST_TEST(y.begin() != y.end());
+#endif
+
+      fps[i](y, v);
+
+      test::check_container(x, v);
+      test::check_equivalent_keys(x);
+    }
+
+    for (std::size_t i = 0; i < len; ++i) {
+      test::check_instances check_;
+
+      test::random_values<T> v(1000, generator);
+      test::object_count count;
+      T y(create(v, count));
+
+      unsigned num_allocs = test::detail::tracker.count_allocations;
+      (void)num_allocs;
+
+      T x(empty(ptr));
+      x = boost::move(y);
+
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+      BOOST_TEST(y.empty());
+      BOOST_TEST(y.begin() == y.end());
+      BOOST_TEST_EQ(y.bucket_count(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, num_allocs);
+#endif
+
+      fps[i](y, v);
+
+      test::check_container(x, v);
+      test::check_equivalent_keys(x);
+    }
+
+    for (std::size_t i = 0; i < len; ++i) {
+      typename T::hasher hf(1);
+      typename T::key_equal eq(1);
+      typename T::allocator_type al1(1);
+      typename T::allocator_type al2(2);
+
+      test::check_instances check_;
+
+      test::random_values<T> v(1000, generator);
+      test::object_count count;
+      T y(v.begin(), v.end(), 0, hf, eq, al1);
+
+      unsigned num_allocs = test::detail::tracker.count_allocations;
+      (void)num_allocs;
+
+      T x(al2);
+      x = boost::move(y);
+
+      bool b = boost::allocator_propagate_on_container_move_assignment<
+        typename T::allocator_type>::type::value;
+      if (b) {
+#if defined(BOOST_UNORDERED_USE_MOVE) ||                                       \
+  !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+        BOOST_TEST(y.empty());
+        BOOST_TEST(y.begin() == y.end());
+        BOOST_TEST_EQ(y.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, num_allocs);
+#else
+        BOOST_TEST_NOT(y.empty());
+        BOOST_TEST(y.begin() != y.end());
+
+#endif
+      } else {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+        BOOST_TEST(y.empty());
+        BOOST_TEST(y.begin() == y.end());
+#else
+        BOOST_TEST_NOT(y.empty());
+        BOOST_TEST(y.begin() != y.end());
+#endif
+      }
+
+      fps[i](y, v);
+
+      test::check_container(x, v);
+      test::check_equivalent_keys(x);
+    }
+  }
+
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    std::allocator<std::pair<test::object const, test::object> > >*
+    test_map_std_alloc;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator2<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >* test_map;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_move> >*
+    test_set_prop_move;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_map_prop_move;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_move> >*
+    test_set_no_prop_move;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_map_no_prop_move;
+
+  UNORDERED_TEST(post_move_tests,
+    ((test_set)(test_map)(test_set_prop_move)(test_map_prop_move)(test_set_no_prop_move)(test_map_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    std::allocator<std::pair<test::object const, test::object> > >*
+    test_map_std_alloc;
+
+  boost::unordered_set<test::object, test::hash, test::equal_to,
+    test::allocator2<test::object> >* test_set;
+  boost::unordered_multiset<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_multiset;
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >* test_map;
+  boost::unordered_multimap<test::object, test::object, test::hash,
+    test::equal_to,
+    test::allocator2<std::pair<test::object const, test::object> > >*
+    test_multimap;
+
+  boost::unordered_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_move> >*
+    test_set_prop_move;
+  boost::unordered_multiset<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_move> >*
+    test_multiset_prop_move;
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_map_prop_move;
+  boost::unordered_multimap<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::propagate_move> >* test_multimap_prop_move;
+
+  boost::unordered_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_move> >*
+    test_set_no_prop_move;
+  boost::unordered_multiset<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_move> >*
+    test_multiset_no_prop_move;
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_map_no_prop_move;
+  boost::unordered_multimap<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_multimap_no_prop_move;
+
+  UNORDERED_TEST(post_move_tests,
+    ((test_set)(test_multiset)(test_map)(test_multimap)(test_set_prop_move)(
+      test_multiset_prop_move)(test_map_prop_move)(test_multimap_prop_move)(
+      test_set_no_prop_move)(test_multiset_no_prop_move)(test_map_no_prop_move)(
+      test_multimap_no_prop_move))(
+      (default_generator)(generate_collisions)(limited_range)))
+#endif
+}
+
+RUN_TESTS()

test/unordered/rehash_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include "../helpers/random_values.hpp"
@@ -81,6 +77,305 @@ namespace rehash_tests {
     BOOST_TEST(postcondition(x, 0));
   }
 
+  template <class X> void rehash_empty_tracking(X*, test::random_generator)
+  {
+    // valid for all load factors
+    float const max_load_factors[] = {
+      0.5f, 1.0f, 1e6f, std::numeric_limits<float>::infinity()};
+
+    std::size_t const max_load_factors_len =
+      sizeof(max_load_factors) / sizeof(*max_load_factors);
+
+    for (std::size_t i = 0; i < max_load_factors_len; ++i) {
+      X x;
+      BOOST_TEST_EQ(x.size(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+
+      x.max_load_factor(max_load_factors[i]);
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.rehash(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.rehash(1000);
+        BOOST_TEST_GE(x.bucket_count(), 1000u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.rehash(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.rehash(1000);
+        BOOST_TEST_GE(x.bucket_count(), 1000u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.rehash(10);
+        BOOST_TEST_GE(x.bucket_count(), 10u);
+        BOOST_TEST_LT(x.bucket_count(), 1000u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+        BOOST_TEST_LT(x.bucket_count(), 1000u);
+
+        x.rehash(1000);
+        BOOST_TEST_GE(x.bucket_count(), 1000u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.rehash(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+
+    for (std::size_t i = 0; i < max_load_factors_len; ++i) {
+      typedef typename X::size_type size_type;
+
+      X x;
+      BOOST_TEST_EQ(x.size(), 0u);
+      BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+      float const mlf = boost::unordered::detail::foa::mlf;
+      x.max_load_factor(max_load_factors[i]);
+#else
+      float const mlf = max_load_factors[i];
+      x.max_load_factor(mlf);
+#endif
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.reserve(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.reserve(1000);
+        BOOST_TEST_GE(
+          x.bucket_count(), static_cast<size_type>(std::ceil(1000 / mlf)));
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.reserve(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+
+        x.reserve(1000);
+        BOOST_TEST_GE(
+          x.bucket_count(), static_cast<size_type>(std::ceil(1000 / mlf)));
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.reserve(10);
+        BOOST_TEST_GE(
+          x.bucket_count(), static_cast<size_type>(std::ceil(10 / mlf)));
+        BOOST_TEST_LT(x.bucket_count(), 1000u);
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+      }
+
+      {
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+        BOOST_TEST_LT(x.bucket_count(), 1000u);
+
+        x.reserve(1000);
+        BOOST_TEST_GE(
+          x.bucket_count(), static_cast<size_type>(std::ceil(1000 / mlf)));
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        x.reserve(0);
+        BOOST_TEST_EQ(x.bucket_count(), 0u);
+        BOOST_TEST_EQ(test::detail::tracker.count_allocations, 0u);
+      }
+    }
+  }
+
+  template <class X>
+  void rehash_nonempty_tracking(X*, test::random_generator generator)
+  {
+    test::random_values<X> const v(1000, generator);
+
+    typedef typename X::size_type size_type;
+
+    float const max_load_factors[] = {0.5f, 1.0f, 1e2f};
+
+    size_type const max_load_factors_len =
+      sizeof(max_load_factors) / sizeof(*max_load_factors);
+
+    for (size_type i = 0; i < max_load_factors_len; ++i) {
+      float const mlf = max_load_factors[i];
+
+      X x(v.begin(), v.end());
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+      x.max_load_factor(mlf);
+
+      size_type bucket_count = x.bucket_count();
+
+      {
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+
+        x.rehash(0);
+        BOOST_TEST_GE(x.bucket_count(),
+          static_cast<size_type>(
+            std::floor(static_cast<float>(x.size()) / x.max_load_factor())));
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        bucket_count = x.bucket_count();
+      }
+
+      {
+        BOOST_TEST_GT(bucket_count, 0u);
+
+        x.rehash(2 * x.bucket_count());
+        BOOST_TEST_GT(x.bucket_count(), bucket_count);
+
+        bucket_count = x.bucket_count();
+      }
+
+      {
+        float const old_mlf = x.max_load_factor();
+
+        BOOST_TEST_GT(bucket_count, 0u);
+
+        x.rehash(bucket_count / 4);
+        BOOST_TEST_LT(x.bucket_count(), bucket_count);
+
+        x.max_load_factor(std::numeric_limits<float>::infinity());
+        x.rehash(0);
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+
+        x.max_load_factor(old_mlf);
+      }
+
+      {
+        std::size_t const max_load =
+          static_cast<std::size_t>(static_cast<double>(x.max_load_factor()) *
+                                   static_cast<double>(x.bucket_count()));
+
+        while (x.size() < max_load) {
+          test::random_values<X> const t(max_load, generator);
+          typename test::random_values<X>::const_iterator pos = t.begin();
+          typename test::random_values<X>::const_iterator end = t.end();
+          for (; pos != end; ++pos) {
+            x.insert(*pos);
+            if (x.size() == max_load) {
+              break;
+            }
+          }
+        }
+
+        while (x.size() > max_load) {
+          x.erase(x.begin());
+        }
+
+        BOOST_TEST_EQ(x.size(), max_load);
+
+        bucket_count = x.bucket_count();
+        x.rehash(x.bucket_count());
+        BOOST_TEST_EQ(x.bucket_count(), bucket_count);
+      }
+    }
+
+    for (size_type i = 0; i < max_load_factors_len; ++i) {
+      X x(v.begin(), v.end());
+      BOOST_TEST_GT(x.size(), 0u);
+      BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+      float const mlf = max_load_factors[i];
+      x.max_load_factor(mlf);
+
+      size_type bucket_count = x.bucket_count();
+
+      {
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+
+        x.reserve(0);
+        BOOST_TEST_GE(x.bucket_count(),
+          static_cast<size_type>(
+            std::floor(static_cast<float>(x.size()) / x.max_load_factor())));
+        BOOST_TEST_GT(test::detail::tracker.count_allocations, 0u);
+
+        bucket_count = x.bucket_count();
+      }
+
+      {
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+
+        x.reserve(
+          2 * (static_cast<size_type>(
+                std::floor(static_cast<float>(x.size()) / x.max_load_factor()) +
+                std::floor(static_cast<float>(x.size()) * x.max_load_factor()))));
+
+        BOOST_TEST_GT(x.bucket_count(), bucket_count);
+
+        bucket_count = x.bucket_count();
+        BOOST_TEST_GT(bucket_count, 1u);
+      }
+
+      {
+        float const old_mlf = x.max_load_factor();
+
+        BOOST_TEST_GT(bucket_count, 4u);
+
+        x.reserve(bucket_count / 4);
+        BOOST_TEST_LT(x.bucket_count(), bucket_count);
+
+        x.max_load_factor(std::numeric_limits<float>::infinity());
+        x.reserve(0);
+        BOOST_TEST_GT(x.bucket_count(), 0u);
+
+        x.max_load_factor(old_mlf);
+      }
+
+      {
+        std::size_t const max_load =
+          static_cast<std::size_t>(static_cast<double>(x.max_load_factor()) *
+                                   static_cast<double>(x.bucket_count()));
+
+        while (x.size() < max_load) {
+          test::random_values<X> const t(max_load, generator);
+          typename test::random_values<X>::const_iterator pos = t.begin();
+          typename test::random_values<X>::const_iterator end = t.end();
+          for (; pos != end; ++pos) {
+            x.insert(*pos);
+            if (x.size() == max_load) {
+              break;
+            }
+          }
+        }
+
+        while (x.size() > max_load) {
+          x.erase(x.begin());
+        }
+
+        BOOST_TEST_EQ(x.size(), max_load);
+
+        bucket_count = x.bucket_count();
+        x.reserve(x.size());
+        BOOST_TEST_EQ(x.bucket_count(), bucket_count);
+      }
+    }
+  }
+
   template <class X> void rehash_test1(X*, test::random_generator generator)
   {
     test::random_values<X> v(1000, generator);
@@ -125,6 +420,15 @@ namespace rehash_tests {
     X x;
     x.max_load_factor(0.25);
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    x.reserve(10000);
+    BOOST_TEST(x.bucket_count() >= 10000);
+
+    x.reserve(0);
+
+    x.reserve(10000000);
+    BOOST_TEST(x.bucket_count() >= 10000000);
+#else
     x.reserve(10000);
     BOOST_TEST(x.bucket_count() >= 40000);
 
@@ -132,6 +436,7 @@ namespace rehash_tests {
 
     x.reserve(10000000);
     BOOST_TEST(x.bucket_count() >= 40000000);
+#endif
   }
 
   template <class X> void reserve_test1(X*, test::random_generator generator)
@@ -192,6 +497,47 @@ namespace rehash_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int>* int_set_ptr;
+  boost::unordered_flat_map<test::movable, test::movable, test::hash,
+    test::equal_to, test::allocator2<test::movable> >* test_map_ptr;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set_tracking;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >*
+    test_map_tracking;
+
+  UNORDERED_TEST(rehash_empty_test1, ((int_set_ptr)(test_map_ptr)))
+  UNORDERED_TEST(rehash_empty_test2,
+    ((int_set_ptr)(test_map_ptr))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_empty_test3,
+    ((int_set_ptr)(test_map_ptr))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(
+    rehash_test1, ((int_set_ptr)(test_map_ptr))(
+                    (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(reserve_empty_test1, ((int_set_ptr)(test_map_ptr)))
+  UNORDERED_TEST(reserve_empty_test2, ((int_set_ptr)(test_map_ptr)))
+  UNORDERED_TEST(
+    reserve_test1, ((int_set_ptr)(test_map_ptr))(
+                     (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(
+    reserve_test2, ((int_set_ptr)(test_map_ptr))(
+                     (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_empty_tracking,
+    ((test_set_tracking)(test_map_tracking))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_nonempty_tracking,
+    ((test_set_tracking)(test_map_tracking))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_set<int>* int_set_ptr;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
     test::allocator2<test::object> >* test_multiset_ptr;
@@ -199,9 +545,17 @@ namespace rehash_tests {
     test::allocator2<test::movable> >* test_map_ptr;
   boost::unordered_multimap<int, int>* int_multimap_ptr;
 
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
+  boost::unordered_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set_tracking;
+  boost::unordered_multiset<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_multiset_tracking;
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >*
+    test_map_tracking;
+  boost::unordered_multimap<test::object, test::object, test::hash,
+    test::equal_to,
+    test::allocator1<std::pair<test::object const, test::object> > >*
+    test_multimap_tracking;
 
   UNORDERED_TEST(rehash_empty_test1,
     ((int_set_ptr)(test_multiset_ptr)(test_map_ptr)(int_multimap_ptr)))
@@ -224,6 +578,13 @@ namespace rehash_tests {
   UNORDERED_TEST(reserve_test2,
     ((int_set_ptr)(test_multiset_ptr)(test_map_ptr)(int_multimap_ptr))(
       (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_empty_tracking,
+    ((test_set_tracking)(test_multiset_tracking)(test_map_tracking)(test_multimap_tracking))(
+      (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_nonempty_tracking,
+    ((test_set_tracking)(test_multiset_tracking)(test_map_tracking)(test_multimap_tracking))(
+      (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 
 RUN_TESTS()

test/unordered/reserve_tests.cpp

@@ -2,12 +2,7 @@
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 
@@ -113,8 +108,8 @@ template <class UnorderedContainer> void reserve_tests()
     s.max_load_factor(0.37f);
     s.reserve(count);
 
-    std::size_t expected_bucket_count =
-      static_cast<std::size_t>(std::ceil(static_cast<float>(count) / 0.37f));
+    std::size_t expected_bucket_count = static_cast<std::size_t>(
+      std::ceil(static_cast<float>(count) / s.max_load_factor()));
 
     BOOST_TEST_GE(total_allocation, expected_bucket_count * sizeof(void*));
     BOOST_TEST_GE(s.bucket_count(), expected_bucket_count);
@@ -173,6 +168,12 @@ template <class UnorderedContainer> void rehash_tests()
     // note, the test is vulnerable to cases where the next calculated bucket
     // count can exceed `prev_count + count`
     //
+#ifdef BOOST_UNORDERED_FOA_TESTS
+    BOOST_TEST_LT(s.bucket_count(), prev_count + count);
+    BOOST_TEST_LE(total_allocation,
+      (prev_count + count) * sizeof(typename UnorderedContainer::value_type) +
+        ((prev_count + count) / 15 + 1) * 16);
+#else
     std::size_t const estimated_bucket_group_size =
       3 * sizeof(void*) + sizeof(std::size_t);
     std::size_t const estimated_bucket_groups =
@@ -182,6 +183,7 @@ template <class UnorderedContainer> void rehash_tests()
     BOOST_TEST_LE(total_allocation,
       (prev_count + count) * sizeof(void*) +
         estimated_bucket_group_size * estimated_bucket_groups);
+#endif
   }
 
   BOOST_TEST_GT(num_allocations, 0u);
@@ -214,6 +216,28 @@ UNORDERED_AUTO_TEST (unordered_set_reserve) {
     BOOST_ASSERT(A<int>(b) == a);
   }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_set<int*, boost::hash<int*>,
+    std::equal_to<int*>, A<int*> >
+    unordered_set;
+
+  typedef boost::unordered_flat_map<int*, int*, boost::hash<int*>,
+    std::equal_to<int*>, A<std::pair<int const*, int*> > >
+    unordered_map;
+
+  bucket_count_constructor<unordered_set>();
+  bucket_count_constructor<unordered_map>();
+
+  range_bucket_constructor<unordered_set>();
+  range_bucket_constructor<unordered_map>();
+
+  reserve_tests<unordered_set>();
+  reserve_tests<unordered_map>();
+
+  rehash_tests<unordered_set>();
+  rehash_tests<unordered_map>();
+
+#else
   typedef boost::unordered_set<int, boost::hash<int>, std::equal_to<int>,
     A<int> >
     unordered_set;
@@ -249,6 +273,7 @@ UNORDERED_AUTO_TEST (unordered_set_reserve) {
   rehash_tests<unordered_map>();
   rehash_tests<unordered_multiset>();
   rehash_tests<unordered_multimap>();
+#endif
 }
 
 RUN_TESTS()

test/unordered/scary_tests.cpp

@@ -2,14 +2,8 @@
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
-
 #include "../helpers/test.hpp"
+#include "../helpers/unordered.hpp"
 #include "../objects/test.hpp"
 
 #include <memory>
@@ -107,8 +101,7 @@ public:
   // ever using it with an int with has a trivial destructor so it eliminates
   // the code and generates a warning about an unused variable
   //
-  template <class U>
-  void destroy(U* p)
+  template <class U> void destroy(U* p)
   {
     (void)p;
     p->~U();
@@ -192,8 +185,7 @@ public:
   // ever using it with an int with has a trivial destructor so it eliminates
   // the code and generates a warning about an unused variable
   //
-  template <class U>
-  void destroy(U* p)
+  template <class U> void destroy(U* p)
   {
     (void)p;
     p->~U();
@@ -224,13 +216,15 @@ template <class C1, class C2> void scary_test()
   typename C2::const_iterator cbegin(x.cbegin());
   BOOST_TEST(cbegin == x.cend());
 
-  BOOST_ASSERT(x.bucket_count() > 0);
+  BOOST_TEST_EQ(x.bucket_count(), 0u);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typename C2::local_iterator lbegin(x.begin(0));
   BOOST_TEST(lbegin == x.end(0));
 
   typename C2::const_local_iterator clbegin(x.cbegin(0));
   BOOST_TEST(clbegin == x.cend(0));
+#endif
 }
 
 template <
@@ -316,11 +310,16 @@ void set_scary_test()
 }
 
 UNORDERED_AUTO_TEST (scary_tests) {
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  map_scary_test<boost::unordered_flat_map>();
+  set_scary_test<boost::unordered_flat_set>();
+#else
   map_scary_test<boost::unordered_map>();
   map_scary_test<boost::unordered_multimap>();
 
   set_scary_test<boost::unordered_set>();
   set_scary_test<boost::unordered_multiset>();
+#endif
 }
 
 RUN_TESTS()

test/unordered/scoped_allocator.cpp

@@ -19,12 +19,7 @@ int main() {}
 // https://github.com/boostorg/unordered/issues/22
 //
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 
@@ -32,10 +27,10 @@ int main() {}
 
 #include <boost/core/ignore_unused.hpp>
 
+#include <scoped_allocator>
 #include <string>
 #include <utility>
 #include <vector>
-#include <scoped_allocator>
 
 namespace test {
   template <class T> struct allocator
@@ -70,9 +65,15 @@ typedef std::scoped_allocator_adaptor<test::allocator<pair_type>,
   test::allocator<boost::uint64_t> >
   allocator_type;
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_map<const boost::uint64_t, vector_type,
+  boost::hash<boost::uint64_t>, std::equal_to<boost::uint64_t>, allocator_type>
+  map_type;
+#else
 typedef boost::unordered_map<const boost::uint64_t, vector_type,
   boost::hash<boost::uint64_t>, std::equal_to<boost::uint64_t>, allocator_type>
   map_type;
+#endif
 
 UNORDERED_AUTO_TEST (scoped_allocator) {
   allocator_type alloc(

test/unordered/simple_tests.cpp

@@ -1,16 +1,12 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
 // This test checks the runtime requirements of containers.
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 #include <cstdlib>
@@ -93,7 +89,11 @@ UNORDERED_AUTO_TEST (simple_tests) {
   srand(14878);
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_set.\n";
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_set<int> set;
+#else
   boost::unordered_set<int> set;
+#endif
   simple_test(set);
 
   set.insert(1);
@@ -101,6 +101,7 @@ UNORDERED_AUTO_TEST (simple_tests) {
   set.insert(1456);
   simple_test(set);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multiset.\n";
   boost::unordered_multiset<int> multiset;
   simple_test(multiset);
@@ -111,15 +112,21 @@ UNORDERED_AUTO_TEST (simple_tests) {
       multiset.insert(index);
   }
   simple_test(multiset);
+#endif
 
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_map.\n";
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<int, int> map;
+#else
   boost::unordered_map<int, int> map;
+#endif
 
   for (int i2 = 0; i2 < 1000; ++i2) {
     map.insert(std::pair<const int, int>(rand(), rand()));
   }
   simple_test(map);
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
   BOOST_LIGHTWEIGHT_TEST_OSTREAM << "Test unordered_multimap.\n";
   boost::unordered_multimap<int, int> multimap;
 
@@ -129,6 +136,7 @@ UNORDERED_AUTO_TEST (simple_tests) {
       multimap.insert(std::pair<const int, int>(index, rand()));
   }
   simple_test(multimap);
+#endif
 }
 
 RUN_TESTS()

test/unordered/swap_tests.cpp

@@ -1,14 +1,10 @@
 
 // Copyright 2006-2009 Daniel James.
+// Copyright 2022 Christian Mazakas.
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include <boost/config.hpp>
 #include <algorithm>
@@ -139,6 +135,53 @@ namespace swap_tests {
     }
   }
 
+  using test::default_generator;
+  using test::generate_collisions;
+  using test::limited_range;
+
+  template <typename T> bool is_propagate(T*)
+  {
+    return T::allocator_type::is_propagate_on_swap;
+  }
+
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, std::allocator<test::object> >* test_map_std_alloc;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::allocator1<test::object> >* test_set;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::allocator1<test::object> >* test_map;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::propagate_swap> >*
+    test_set_prop_swap;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to, test::cxx11_allocator<test::object, test::propagate_swap> >*
+    test_map_prop_swap;
+
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_swap> >*
+    test_set_no_prop_swap;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    test::cxx11_allocator<test::object, test::no_propagate_swap> >*
+    test_map_no_prop_swap;
+
+  UNORDERED_AUTO_TEST (check_traits) {
+    BOOST_TEST(!is_propagate(test_set));
+    BOOST_TEST(is_propagate(test_set_prop_swap));
+    BOOST_TEST(!is_propagate(test_set_no_prop_swap));
+  }
+
+  UNORDERED_TEST(swap_tests1,
+    ((test_map_std_alloc)(test_set)(test_map)(test_set_prop_swap)(test_map_prop_swap)(test_set_no_prop_swap)(test_map_no_prop_swap))(
+      (default_generator)(generate_collisions)(limited_range)))
+
+  UNORDERED_TEST(swap_tests2,
+    ((test_set)(test_map)(test_set_prop_swap)(test_map_prop_swap)(test_set_no_prop_swap)(test_map_no_prop_swap))(
+      (default_generator)(generate_collisions)(limited_range)))
+#else
   boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
     std::allocator<test::object> >* test_map_std_alloc;
 
@@ -178,15 +221,6 @@ namespace swap_tests {
     test::cxx11_allocator<test::object, test::no_propagate_swap> >*
     test_multimap_no_prop_swap;
 
-  template <typename T> bool is_propagate(T*)
-  {
-    return T::allocator_type::is_propagate_on_swap;
-  }
-
-  using test::default_generator;
-  using test::generate_collisions;
-  using test::limited_range;
-
   UNORDERED_AUTO_TEST (check_traits) {
     BOOST_TEST(!is_propagate(test_set));
     BOOST_TEST(is_propagate(test_set_prop_swap));
@@ -207,5 +241,6 @@ namespace swap_tests {
       test_set_no_prop_swap)(test_multiset_no_prop_swap)(test_map_no_prop_swap)(
       test_multimap_no_prop_swap))(
       (default_generator)(generate_collisions)(limited_range)))
+#endif
 }
 RUN_TESTS()

test/unordered/transparent_tests.cpp

@@ -2,12 +2,7 @@
 // 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)
 
-// clang-format off
-#include "../helpers/prefix.hpp"
-#include <boost/unordered_set.hpp>
-#include <boost/unordered_map.hpp>
-#include "../helpers/postfix.hpp"
-// clang-format on
+#include "../helpers/unordered.hpp"
 
 #include "../helpers/test.hpp"
 
@@ -1053,14 +1048,25 @@ template <class UnorderedMap> struct convertible_to_const_iterator
   }
 };
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_map<int, int, transparent_hasher,
+  transparent_key_equal>
+  transparent_unordered_map;
+#else
 typedef boost::unordered_map<int, int, transparent_hasher,
   transparent_key_equal>
   transparent_unordered_map;
+#endif
 
 // test that in the presence of the member function template `erase()`, we still
 // invoke the correct iterator overloads when the type is implicitly convertible
 //
-transparent_unordered_map::iterator map_erase_overload_compile_test()
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void
+#else
+transparent_unordered_map::iterator
+#endif
+map_erase_overload_compile_test()
 {
   convertible_to_iterator<transparent_unordered_map> c;
   transparent_unordered_map map;
@@ -1069,7 +1075,11 @@ transparent_unordered_map::iterator map_erase_overload_compile_test()
   return map.erase(c);
 }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void
+#else
 transparent_unordered_map::const_iterator
+#endif
 map_erase_const_overload_compile_test()
 {
   convertible_to_const_iterator<transparent_unordered_map> c;
@@ -1079,6 +1089,7 @@ map_erase_const_overload_compile_test()
   return map.erase(c);
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 typedef boost::unordered_multimap<int, int, transparent_hasher,
   transparent_key_equal>
   transparent_unordered_multimap;
@@ -1101,6 +1112,7 @@ multimap_erase_const_overload_compile_test()
   pos = c;
   return map.erase(c);
 }
+#endif
 
 template <class UnorderedMap> void test_map_transparent_erase()
 {
@@ -1197,14 +1209,25 @@ template <class UnorderedMap> void test_map_non_transparent_erase()
   BOOST_TEST_EQ(key::count_, key_count);
 }
 
+#if BOOST_UNORDERED_FOA_TESTS
+typedef boost::unordered_flat_set<int, transparent_hasher,
+  transparent_key_equal>
+  transparent_unordered_set;
+#else
 typedef boost::unordered_set<int, transparent_hasher, transparent_key_equal>
   transparent_unordered_set;
 
 typedef boost::unordered_multiset<int, transparent_hasher,
   transparent_key_equal>
   transparent_unordered_multiset;
+#endif
 
-transparent_unordered_set::iterator set_erase_overload_compile_test()
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void
+#else
+transparent_unordered_set::iterator
+#endif
+set_erase_overload_compile_test()
 {
   convertible_to_iterator<transparent_unordered_set> c;
   transparent_unordered_set set;
@@ -1213,7 +1236,11 @@ transparent_unordered_set::iterator set_erase_overload_compile_test()
   return set.erase(c);
 }
 
+#ifdef BOOST_UNORDERED_FOA_TESTS
+void
+#else
 transparent_unordered_set::const_iterator
+#endif
 set_erase_const_overload_compile_test()
 {
   convertible_to_const_iterator<transparent_unordered_set> c;
@@ -1223,6 +1250,7 @@ set_erase_const_overload_compile_test()
   return set.erase(c);
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 transparent_unordered_multiset::iterator multiset_erase_overload_compile_test()
 {
   convertible_to_iterator<transparent_unordered_multiset> c;
@@ -1241,6 +1269,7 @@ multiset_erase_const_overload_compile_test()
   pos = c;
   return set.erase(c);
 }
+#endif
 
 template <class UnorderedSet> void test_set_transparent_erase()
 {
@@ -1337,6 +1366,7 @@ template <class UnorderedSet> void test_set_non_transparent_erase()
   BOOST_TEST_EQ(key::count_, key_count);
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 // test that in the presence of the member function template `extract()`, we
 // still invoke the correct iterator overloads when the type is implicitly
 // convertible
@@ -1359,9 +1389,11 @@ multimap_extract_const_overload_compile_test()
   pos = c;
   return map.extract(c);
 }
+#endif
 
 template <class UnorderedMap> void test_map_transparent_extract()
 {
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename UnorderedMap::node_type node_type;
   typedef typename UnorderedMap::const_iterator const_iterator;
   typedef std::pair<const_iterator, const_iterator> const_iterator_pair;
@@ -1397,10 +1429,12 @@ template <class UnorderedMap> void test_map_transparent_extract()
   BOOST_TEST(nh.empty());
 
   BOOST_TEST_EQ(key::count_, expected_key_count);
+#endif
 }
 
 template <class UnorderedMap> void test_map_non_transparent_extract()
 {
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename UnorderedMap::node_type node_type;
   typedef typename UnorderedMap::const_iterator const_iterator;
   typedef std::pair<const_iterator, const_iterator> const_iterator_pair;
@@ -1441,8 +1475,10 @@ template <class UnorderedMap> void test_map_non_transparent_extract()
   ++key_count;
   BOOST_TEST(nh.empty());
   BOOST_TEST_EQ(key::count_, key_count);
+#endif
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 transparent_unordered_set::node_type set_extract_overload_compile_test()
 {
   convertible_to_iterator<transparent_unordered_set> c;
@@ -1480,9 +1516,11 @@ multiset_extract_const_overload_compile_test()
   pos = c;
   return set.extract(c);
 }
+#endif
 
 template <class UnorderedSet> void test_set_transparent_extract()
 {
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename UnorderedSet::node_type node_type;
 
   count_reset();
@@ -1526,10 +1564,12 @@ template <class UnorderedSet> void test_set_transparent_extract()
   BOOST_TEST_EQ(set.size(), set_size);
 
   BOOST_TEST_EQ(key::count_, expected_key_count);
+#endif
 }
 
 template <class UnorderedSet> void test_set_non_transparent_extract()
 {
+#ifndef BOOST_UNORDERED_FOA_TESTS
   typedef typename UnorderedSet::node_type node_type;
 
   count_reset();
@@ -1583,13 +1623,22 @@ template <class UnorderedSet> void test_set_non_transparent_extract()
   BOOST_TEST_EQ(set.size(), set_size);
 
   BOOST_TEST_EQ(key::count_, key_count);
+#endif
 }
 
+template <class Key, class T, class Hash, class KeyEqual> struct map_type
+{
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_map<Key, T, Hash, KeyEqual> type;
+#else
+  typedef boost::unordered_map<Key, T, Hash, KeyEqual> type;
+#endif
+};
+
 void test_unordered_map()
 {
   {
-    typedef boost::unordered_map<key, int, transparent_hasher,
-      transparent_key_equal>
+    typedef map_type<key, int, transparent_hasher, transparent_key_equal>::type
       unordered_map;
 
     test_map_transparent_count<unordered_map>();
@@ -1602,7 +1651,7 @@ void test_unordered_map()
   {
     // non-transparent Hash, non-transparent KeyEqual
     //
-    typedef boost::unordered_map<key, int, hasher, key_equal> unordered_map;
+    typedef map_type<key, int, hasher, key_equal>::type unordered_map;
 
     test_map_non_transparent_count<unordered_map>();
     test_map_non_transparent_find<unordered_map>();
@@ -1614,7 +1663,7 @@ void test_unordered_map()
   {
     // transparent Hash, non-transparent KeyEqual
     //
-    typedef boost::unordered_map<key, int, transparent_hasher, key_equal>
+    typedef map_type<key, int, transparent_hasher, key_equal>::type
       unordered_map;
 
     test_map_non_transparent_count<unordered_map>();
@@ -1627,7 +1676,7 @@ void test_unordered_map()
   {
     // non-transparent Hash, transparent KeyEqual
     //
-    typedef boost::unordered_map<key, int, hasher, transparent_key_equal>
+    typedef map_type<key, int, hasher, transparent_key_equal>::type
       unordered_map;
 
     test_map_non_transparent_count<unordered_map>();
@@ -1638,6 +1687,7 @@ void test_unordered_map()
   }
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 void test_unordered_multimap()
 {
   {
@@ -1691,11 +1741,21 @@ void test_unordered_multimap()
     test_map_non_transparent_extract<unordered_multimap>();
   }
 }
+#endif
+
+template <class Key, class Hash, class KeyEqual> struct set_type
+{
+#ifdef BOOST_UNORDERED_FOA_TESTS
+  typedef boost::unordered_flat_set<Key, Hash, KeyEqual> type;
+#else
+  typedef boost::unordered_set<Key, Hash, KeyEqual> type;
+#endif
+};
 
 void test_unordered_set()
 {
   {
-    typedef boost::unordered_set<key, transparent_hasher, transparent_key_equal>
+    typedef set_type<key, transparent_hasher, transparent_key_equal>::type
       unordered_set;
 
     test_set_transparent_count<unordered_set>();
@@ -1708,7 +1768,7 @@ void test_unordered_set()
   {
     // non-transparent Hash, non-transparent KeyEqual
     //
-    typedef boost::unordered_set<key, hasher, key_equal> unordered_set;
+    typedef set_type<key, hasher, key_equal>::type unordered_set;
 
     test_set_non_transparent_count<unordered_set>();
     test_set_non_transparent_find<unordered_set>();
@@ -1720,8 +1780,7 @@ void test_unordered_set()
   {
     // transparent Hash, non-transparent KeyEqual
     //
-    typedef boost::unordered_set<key, transparent_hasher, key_equal>
-      unordered_set;
+    typedef set_type<key, transparent_hasher, key_equal>::type unordered_set;
 
     test_set_non_transparent_count<unordered_set>();
     test_set_non_transparent_find<unordered_set>();
@@ -1733,8 +1792,7 @@ void test_unordered_set()
   {
     // non-transparent Hash, transparent KeyEqual
     //
-    typedef boost::unordered_set<key, hasher, transparent_key_equal>
-      unordered_set;
+    typedef set_type<key, hasher, transparent_key_equal>::type unordered_set;
 
     test_set_non_transparent_count<unordered_set>();
     test_set_non_transparent_find<unordered_set>();
@@ -1744,6 +1802,7 @@ void test_unordered_set()
   }
 }
 
+#ifndef BOOST_UNORDERED_FOA_TESTS
 void test_unordered_multiset()
 {
   {
@@ -1796,12 +1855,16 @@ void test_unordered_multiset()
     test_set_non_transparent_extract<unordered_set>();
   }
 }
+#endif
 
 UNORDERED_AUTO_TEST (transparent_ops) {
   test_unordered_map();
-  test_unordered_multimap();
   test_unordered_set();
+
+#ifndef BOOST_UNORDERED_FOA_TESTS
+  test_unordered_multimap();
   test_unordered_multiset();
+#endif
 }
 
 RUN_TESTS()