Merge pull request #146 from cmazakas/feature/rehash-doc-updates

Rehash Doc Updates

.appveyor.yml

@@ -85,7 +85,14 @@ environment:
     - 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

@@ -200,7 +200,7 @@ 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
       {
@@ -2054,12 +2054,14 @@ 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 +2071,18 @@ 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 +2095,12 @@ 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 +2372,6 @@ 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 +2400,9 @@ 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 +2434,14 @@ 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 +2470,13 @@ 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 +2486,13 @@ 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 +2524,17 @@ 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 +3443,18 @@ 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/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/exception/insert_exception_tests.cpp

@@ -95,7 +95,7 @@ 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);
@@ -393,7 +393,7 @@ 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);

test/unordered/assign_tests.cpp

@@ -45,6 +45,7 @@ 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 +95,7 @@ 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);
     }
 

test/unordered/constructor_tests.cpp

@@ -35,6 +35,7 @@ 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 +74,7 @@ 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 +142,7 @@ 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 +169,7 @@ 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 +329,7 @@ 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 +385,104 @@ 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)
   {
@@ -422,6 +525,10 @@ 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)))
+
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 
   UNORDERED_AUTO_TEST (test_default_initializer_list) {

test/unordered/copy_tests.cpp

@@ -43,6 +43,23 @@ 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 +108,22 @@ 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 +139,21 @@ 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 +168,22 @@ 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 +199,21 @@ 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_;
 

test/unordered/move_tests.cpp

@@ -18,6 +18,9 @@
 #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
@@ -70,6 +73,10 @@ namespace move_tests {
       BOOST_TEST(test::equivalent(y.get_allocator(), al));
       BOOST_TEST(y.max_load_factor() == 1.0);
       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);
@@ -233,6 +253,32 @@ 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);
+      BOOST_TEST(y.max_load_factor() == 0.25);
+
+      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_;
 
@@ -298,17 +344,533 @@ namespace move_tests {
     }
   }
 
+  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>,
+      extract<T>,
+      merge<T>,
+      erase_with_pred<T>,
+      container_swap<T>,
+      buckets<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);
+
+      BOOST_TEST_NOT(y.empty());
+      BOOST_TEST(y.begin() != y.end());
+
+      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 {
+        BOOST_TEST_NOT(y.empty());
+        BOOST_TEST(y.begin() != y.end());
+      }
+
+      fps[i](y, v);
+
+      test::check_container(x, v);
+      test::check_equivalent_keys(x);
+    }
+  }
+
   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 +879,12 @@ 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> >*
@@ -330,12 +893,12 @@ 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;
+    test::cxx11_allocator<std::pair<test::object const, test::object>,
+      test::no_propagate_move> >* test_multimap_no_prop_move;
 
   using test::default_generator;
   using test::generate_collisions;
@@ -367,6 +930,12 @@ 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)))
+  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)))
 }
 
 RUN_TESTS()

test/unordered/noexcept_tests.cpp

@@ -11,6 +11,7 @@
 // clang-format on
 
 #include "../helpers/test.hpp"
+#include "../helpers/fwd.hpp"
 
 #if defined(BOOST_MSVC)
 #pragma warning(push)
@@ -247,37 +248,65 @@ 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) {
@@ -318,4 +347,80 @@ 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);
+}
+
+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;
+
+using test::default_generator;
+
+UNORDERED_TEST(test_nothrow_move_assign_when_noexcept,
+  ((throwing_set_alloc1)(throwing_set_alloc2))((default_generator)))
+
 RUN_TESTS()

test/unordered/rehash_tests.cpp

@@ -81,6 +81,300 @@ 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);
+
+      float const mlf = max_load_factors[i];
+      x.max_load_factor(mlf);
+
+      {
+        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);
@@ -199,6 +493,18 @@ namespace rehash_tests {
     test::allocator2<test::movable> >* test_map_ptr;
   boost::unordered_multimap<int, int>* int_multimap_ptr;
 
+  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;
+
   using test::default_generator;
   using test::generate_collisions;
   using test::limited_range;
@@ -224,6 +530,12 @@ 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)))
 }
 
 RUN_TESTS()

test/unordered/scary_tests.cpp

@@ -224,7 +224,7 @@ 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);
 
   typename C2::local_iterator lbegin(x.begin(0));
   BOOST_TEST(lbegin == x.end(0));