From 867e60113b0f703dd38bd61ad6b6b314bed5f472 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 12:55:28 -0800
Subject: [PATCH 1/8] Add SFINAE helpers to type_traits.hpp

---
 .../boost/unordered/detail/implementation.hpp | 12 -----
 .../boost/unordered/detail/type_traits.hpp    | 50 +++++++++++++++++++
 2 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/include/boost/unordered/detail/implementation.hpp b/include/boost/unordered/detail/implementation.hpp
index 48a0170d..d953b313 100644
--- a/include/boost/unordered/detail/implementation.hpp
+++ b/include/boost/unordered/detail/implementation.hpp
@@ -182,18 +182,6 @@
 #endif
 #endif
 
-// BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
-
-#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
-#if BOOST_COMP_CLANG && __cplusplus >= 201703
-#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 1
-#endif
-#endif
-
-#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
-#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 0
-#endif
-
 namespace boost {
   namespace unordered {
     namespace detail {
diff --git a/include/boost/unordered/detail/type_traits.hpp b/include/boost/unordered/detail/type_traits.hpp
index 3d7dcf67..3fe2f404 100644
--- a/include/boost/unordered/detail/type_traits.hpp
+++ b/include/boost/unordered/detail/type_traits.hpp
@@ -14,6 +14,25 @@
 #include <boost/type_traits/integral_constant.hpp>
 #include <boost/type_traits/is_convertible.hpp>
 #include <boost/type_traits/make_void.hpp>
+#include <boost/type_traits/type_identity.hpp>
+
+#if !defined(BOOST_NO_CXX17_DEDUCTION_GUIDES)
+#include <boost/type_traits/enable_if.hpp>
+#include <boost/type_traits/is_integral.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#endif
+
+// BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+
+#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
+#if !defined(BOOST_NO_CXX17_DEDUCTION_GUIDES)
+#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 1
+#endif
+#endif
+
+#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
+#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 0
+#endif
 
 namespace boost {
   namespace unordered {
@@ -52,6 +71,37 @@ namespace boost {
           !boost::is_convertible<Key, iterator>::value &&
           !boost::is_convertible<Key, const_iterator>::value;
       };
+
+#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+      // https://eel.is/c++draft/container.requirements#container.alloc.reqmts-34
+      // https://eel.is/c++draft/container.requirements#unord.req.general-243
+
+      template <class InputIterator>
+      constexpr bool const is_input_iterator_v =
+        !boost::is_integral<InputIterator>::value;
+
+      template <class A, class = void> struct is_allocator
+      {
+        constexpr static bool const value = false;
+      };
+
+      template <class A>
+      struct is_allocator<A,
+        boost::void_t<typename A::value_type,
+          decltype(std::declval<A&>().allocate(std::size_t{}))> >
+      {
+        constexpr static bool const value = true;
+      };
+
+      template <class A>
+      constexpr bool const is_allocator_v = is_allocator<A>::value;
+
+      template <class H>
+      constexpr bool const is_hash_v =
+        !boost::is_integral<H>::value && !is_allocator_v<H>;
+
+      template <class P> constexpr bool const is_pred_v = !is_allocator_v<P>;
+#endif
     } // namespace detail
   }   // namespace unordered
 } // namespace boost

From 2949b37490dfadbfd5c2139b510c1ff0f621fd05 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 10:26:30 -0800
Subject: [PATCH 2/8] Flesh out deduction_tests to include
 unordered_[multi]set, update to use BOOST_TEST_TRAIT_SAME

---
 test/unordered/deduction_tests.cpp | 441 ++++++++++++++++-------------
 1 file changed, 248 insertions(+), 193 deletions(-)

diff --git a/test/unordered/deduction_tests.cpp b/test/unordered/deduction_tests.cpp
index cffb0c1d..e808f656 100644
--- a/test/unordered/deduction_tests.cpp
+++ b/test/unordered/deduction_tests.cpp
@@ -3,11 +3,14 @@
 // 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 <boost/core/lightweight_test_trait.hpp>
 #include <boost/unordered_map.hpp>
+#include <boost/unordered_set.hpp>
 #include <iostream>
 #include <vector>
 
 #if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+
 struct hash_equals
 {
   template <typename T> bool operator()(T const& x) const
@@ -33,22 +36,15 @@ template <typename T> struct test_allocator
   bool operator==(test_allocator const&) const { return true; }
   bool operator!=(test_allocator const&) const { return false; }
 };
-#endif
 
-int main()
+template <template <class...> class UnorderedMap> void map_tests()
 {
-  std::cout << "BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES: "
-            << BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES << std::endl;
-
-#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
   std::vector<std::pair<int, int> > x;
   x.push_back(std::make_pair(1, 3));
   x.push_back(std::make_pair(5, 10));
   test_allocator<std::pair<const int, int> > pair_allocator;
   hash_equals f;
 
-  // unordered_map
-
   /*
    template<class InputIterator,
            class Hash = hash<iter_key_t<InputIterator>>,
@@ -63,32 +59,28 @@ int main()
   */
 
   {
-    boost::unordered_map m(x.begin(), x.end());
-    static_assert(
-      std::is_same<decltype(m), boost::unordered_map<int, int> >::value);
-  }
-
-  /* Ambiguous:
-  {
-    boost::unordered_map m(x.begin(), x.end(), 0, std::hash<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  std::hash<int>>>::value);
+    UnorderedMap m(x.begin(), x.end());
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int>);
   }
 
   {
-    boost::unordered_map m(x.begin(), x.end(), 0, std::hash<int>(),
-  std::equal_to<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  std::hash<int>, std::equal_to<int>>>::value);
+    UnorderedMap m(x.begin(), x.end(), 0, std::hash<int>());
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int, std::hash<int> >);
   }
-  */
 
   {
-    boost::unordered_map m(x.begin(), x.end(), 0, std::hash<int>(),
+    UnorderedMap m(
+      x.begin(), x.end(), 0, std::hash<int>(), std::equal_to<int>());
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, std::hash<int>, std::equal_to<int> >);
+  }
+
+  {
+    UnorderedMap m(x.begin(), x.end(), 0, std::hash<int>(),
       std::equal_to<int>(), pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_map<int, int, std::hash<int>, std::equal_to<int>,
-        test_allocator<std::pair<const int, int> > > >::value);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, std::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
 
   /*
@@ -102,33 +94,51 @@ int main()
   */
 
   {
-    boost::unordered_map m({std::pair<int const, int>(1, 2)});
-    static_assert(
-      std::is_same<decltype(m), boost::unordered_map<int, int> >::value);
-  }
-
-  /* Ambiguous
-  {
-    boost::unordered_map m({std::pair<int const, int>(1,2)}, 0,
-  std::hash<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  std::hash<int>>>::value);
+    UnorderedMap m({std::pair<int const, int>(1, 2)});
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int>);
   }
 
   {
-    boost::unordered_map m({std::pair<int const, int>(1,2)}, 0,
-  std::hash<int>(), std::equal_to<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  std::hash<int>, std::equal_to<int>>>::value);
+    UnorderedMap m({std::pair<int, int>(1, 2)});
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int>);
   }
-  */
 
   {
-    boost::unordered_map m(
-      {std::pair<int const, int>(1, 2)}, 0, f, f, pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_map<int, int, hash_equals, hash_equals,
-        test_allocator<std::pair<const int, int> > > >::value);
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, 0, std::hash<int>());
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int, std::hash<int> >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int, int>(1, 2)}, 0, std::hash<int>());
+    BOOST_TEST_TRAIT_SAME(decltype(m), UnorderedMap<int, int, std::hash<int> >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, 0, std::hash<int>(),
+      std::equal_to<int>());
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, std::hash<int>, std::equal_to<int> >);
+  }
+
+  {
+    UnorderedMap m(
+      {std::pair<int, int>(1, 2)}, 0, std::hash<int>(), std::equal_to<int>());
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, std::hash<int>, std::equal_to<int> >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, 0, f, f, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, hash_equals, hash_equals,
+                     test_allocator<std::pair<const int, int> > >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int, int>(1, 2)}, 0, f, f, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, hash_equals, hash_equals,
+                     test_allocator<std::pair<const int, int> > >);
   }
 
   /*
@@ -141,14 +151,12 @@ int main()
                        Allocator>;
   */
 
-  /* Ambiguous
   {
-    boost::unordered_map m(x.begin(), x.end(), 0u, pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_map<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
+    UnorderedMap m(x.begin(), x.end(), 0u, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
-  */
 
   /*
     template<class InputIterator, class Allocator>
@@ -159,14 +167,12 @@ int main()
                        Allocator>;
   */
 
-  /* No constructor:
   {
-    boost::unordered_map m(x.begin(), x.end(), pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_map<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
+    UnorderedMap m(x.begin(), x.end(), pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
-  */
 
   /*
   template<class InputIterator, class Hash, class Allocator>
@@ -177,14 +183,12 @@ int main()
                        equal_to<iter_key_t<InputIterator>>, Allocator>;
   */
 
-  /* Ambiguous
   {
-    boost::unordered_map m(x.begin(), x.end(), 0u, f, pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_map<int, int,
-  hash_equals, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
+    UnorderedMap m(x.begin(), x.end(), 0u, f, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, hash_equals, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
-  */
 
   /*
     template<class Key, class T, typename Allocator>
@@ -194,14 +198,19 @@ int main()
       -> unordered_map<Key, T, hash<Key>, equal_to<Key>, Allocator>;
   */
 
-  /* Ambiguous
   {
-    boost::unordered_map m({std::pair<int const, int>(1,2)}, 0, pair_allocator);
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, 0, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int, int>(1, 2)}, 0, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
-  */
 
   /*
   template<class Key, class T, typename Allocator>
@@ -210,10 +219,17 @@ int main()
   */
 
   {
-    boost::unordered_map m({std::pair<int const, int>(1, 2)}, pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_map<int, int, boost::hash<int>, std::equal_to<int>,
-        test_allocator<std::pair<const int, int> > > >::value);
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
+  }
+
+  {
+    UnorderedMap m({std::pair<int, int>(1, 2)}, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
 
   /*
@@ -224,129 +240,168 @@ int main()
       -> unordered_map<Key, T, Hash, equal_to<Key>, Allocator>;
   */
 
-  /* Ambiguous
   {
-    boost::unordered_map m({std::pair<int const, int>(1,2)}, 0, f,
-  pair_allocator);
-    static_assert(std::is_same<decltype(m),boost::unordered_map<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
-  }
-  */
-
-  // unordered_multimap
-
-  {
-    boost::unordered_multimap m(x.begin(), x.end());
-    static_assert(
-      std::is_same<decltype(m), boost::unordered_multimap<int, int> >::value);
-  }
-
-  /* Ambiguous:
-  {
-    boost::unordered_multimap m(x.begin(), x.end(), 0, std::hash<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-  std::hash<int>>>::value);
+    UnorderedMap m({std::pair<int const, int>(1, 2)}, 0, f, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, hash_equals, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
   }
 
   {
-    boost::unordered_multimap m(x.begin(), x.end(), 0, std::hash<int>(),
-  std::equal_to<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-  std::hash<int>, std::equal_to<int>>>::value);
+    UnorderedMap m({std::pair<int, int>(1, 2)}, 0, f, pair_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(m), UnorderedMap<int, int, hash_equals, std::equal_to<int>,
+                     test_allocator<std::pair<const int, int> > >);
+  }
+}
+
+template <template <class...> class UnorderedSet> void set_tests()
+{
+  std::vector<int> y;
+  y.push_back(1);
+  y.push_back(2);
+
+  hash_equals f;
+
+  test_allocator<int> int_allocator;
+
+  /*   template<class InputIt,
+            class Hash = std::hash<typename
+    std::iterator_traits<InputIt>::value_type>, class Pred =
+    std::equal_to<typename std::iterator_traits<InputIt>::value_type>, class
+    Alloc = std::allocator<typename std::iterator_traits<InputIt>::value_type>>
+    unordered_set(InputIt, InputIt,
+            typename see below ::size_type = see below,
+            Hash = Hash(), Pred = Pred(), Alloc = Alloc())
+      -> unordered_set<typename std::iterator_traits<InputIt>::value_type, Hash,
+    Pred, Alloc>; */
+
+  {
+    UnorderedSet s(y.begin(), y.end());
+    BOOST_TEST_TRAIT_SAME(decltype(s), UnorderedSet<int>);
+  }
+
+  {
+    UnorderedSet s(y.begin(), y.end(), 0, std::hash<int>());
+    BOOST_TEST_TRAIT_SAME(decltype(s), UnorderedSet<int, std::hash<int> >);
+  }
+
+  {
+    UnorderedSet s(
+      y.begin(), y.end(), 0, std::hash<int>(), std::equal_to<int>());
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, std::hash<int>, std::equal_to<int> >);
+  }
+
+  {
+    UnorderedSet s(y.begin(), y.end(), 0, std::hash<int>(),
+      std::equal_to<int>(), int_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, std::hash<int>, std::equal_to<int>,
+                     test_allocator<int> >);
+  }
+
+  /* template<class T,
+           class Hash = std::hash<T>,
+           class Pred = std::equal_to<T>,
+           class Alloc = std::allocator<T>>
+  unordered_set(std::initializer_list<T>,
+           typename see below::size_type = see below,
+           Hash = Hash(), Pred = Pred(), Alloc = Alloc())
+    -> unordered_set<T, Hash, Pred, Alloc>; */
+
+  {
+    UnorderedSet s({1, 2});
+    BOOST_TEST_TRAIT_SAME(decltype(s), UnorderedSet<int>);
+  }
+
+  {
+    UnorderedSet s({1, 2}, 0, std::hash<int>());
+    BOOST_TEST_TRAIT_SAME(decltype(s), UnorderedSet<int, std::hash<int> >);
+  }
+
+  {
+    UnorderedSet s({1, 2}, 0, std::hash<int>(), std::equal_to<int>());
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, std::hash<int>, std::equal_to<int> >);
+  }
+
+  {
+    UnorderedSet s(
+      {1, 2}, 0, std::hash<int>(), std::equal_to<int>(), int_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, std::hash<int>, std::equal_to<int>,
+                     test_allocator<int> >);
+  }
+
+  {
+    UnorderedSet s({1, 2}, 0, f, f, int_allocator);
+    BOOST_TEST_TRAIT_SAME(decltype(s),
+      UnorderedSet<int, hash_equals, hash_equals, test_allocator<int> >);
+  }
+
+  /* template<class InputIt, class Alloc>
+  unordered_set(InputIt, InputIt, typename see below::size_type, Alloc)
+    -> unordered_set<typename std::iterator_traits<InputIt>::value_type,
+                std::hash<typename std::iterator_traits<InputIt>::value_type>,
+                std::equal_to<typename
+  std::iterator_traits<InputIt>::value_type>, Alloc>; */
+
+  {
+    UnorderedSet s(y.begin(), y.end(), 0u, int_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<int> >);
+  }
+
+  /* template<class InputIt, class Hash, class Alloc>
+  unordered_set(InputIt, InputIt, typename see below::size_type, Hash, Alloc)
+    -> unordered_set<typename std::iterator_traits<InputIt>::value_type, Hash,
+               std::equal_to<typename
+  std::iterator_traits<InputIt>::value_type>, Allocator>; */
+
+  {
+    UnorderedSet s(y.begin(), y.end(), 0u, f, int_allocator);
+    BOOST_TEST_TRAIT_SAME(decltype(s),
+      UnorderedSet<int, hash_equals, std::equal_to<int>, test_allocator<int> >);
+  }
+
+  /*   template<class T, class Allocator>
+  unordered_set(std::initializer_list<T>, typename see below::size_type,
+  Allocator)
+    -> unordered_set<T, std::hash<T>, std::equal_to<T>, Alloc>; */
+
+  {
+    UnorderedSet s({1, 2}, 0u, int_allocator);
+    BOOST_TEST_TRAIT_SAME(
+      decltype(s), UnorderedSet<int, boost::hash<int>, std::equal_to<int>,
+                     test_allocator<int> >);
+  }
+
+  /* template<class T, class Hash, class Alloc>
+  unordered_set(std::initializer_list<T>, typename see below::size_type, Hash,
+  Alloc)
+    -> unordered_set<T, Hash, std::equal_to<T>, Alloc>; */
+  {
+    UnorderedSet s({1, 2}, 0u, f, int_allocator);
+    BOOST_TEST_TRAIT_SAME(decltype(s),
+      UnorderedSet<int, hash_equals, std::equal_to<int>, test_allocator<int> >);
   }
-  */
-
-  {
-    boost::unordered_multimap m(x.begin(), x.end(), 0, std::hash<int>(),
-      std::equal_to<int>(), pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_multimap<int, int, std::hash<int>, std::equal_to<int>,
-        test_allocator<std::pair<const int, int> > > >::value);
-  }
-
-  {
-    boost::unordered_multimap m({std::pair<int const, int>(1, 2)});
-    static_assert(
-      std::is_same<decltype(m), boost::unordered_multimap<int, int> >::value);
-  }
-
-  /* Ambiguous
-  {
-    boost::unordered_multimap m({std::pair<int const, int>(1,2)}, 0,
-  std::hash<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-  std::hash<int>>>::value);
-  }
-
-  {
-    boost::unordered_multimap m({std::pair<int const, int>(1,2)}, 0,
-  std::hash<int>(), std::equal_to<int>());
-    static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-  std::hash<int>, std::equal_to<int>>>::value);
-  }
-  */
-
-  {
-    boost::unordered_multimap m(
-      {std::pair<int const, int>(1, 2)}, 0, f, f, pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_multimap<int, int, hash_equals, hash_equals,
-        test_allocator<std::pair<const int, int> > > >::value);
-  }
-
-  /* Ambiguous
-  {
-    boost::unordered_multimap m(x.begin(), x.end(), 0u, pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_multimap<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
-  }
-  */
-
-  /* No constructor:
-  {
-    boost::unordered_multimap m(x.begin(), x.end(), pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_multimap<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
-  }
-  */
-
-  /* Ambiguous
-  {
-    boost::unordered_multimap m(x.begin(), x.end(), 0u, f, pair_allocator);
-    static_assert(std::is_same<decltype(m), boost::unordered_multimap<int, int,
-  hash_equals, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
-  }
-
-  {
-    boost::unordered_multimap m({std::pair<int const, int>(1,2)}, 0,
-  pair_allocator);
-    static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-  boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-  int>>>>::value);
-  }
-  */
-
-  {
-    boost::unordered_multimap m(
-      {std::pair<int const, int>(1, 2)}, pair_allocator);
-    static_assert(std::is_same<decltype(m),
-      boost::unordered_multimap<int, int, boost::hash<int>, std::equal_to<int>,
-        test_allocator<std::pair<const int, int> > > >::value);
-  }
-
-/* Ambiguous
-{
-  boost::unordered_multimap m({std::pair<int const, int>(1,2)}, 0, f,
-pair_allocator);
-  static_assert(std::is_same<decltype(m),boost::unordered_multimap<int, int,
-boost::hash<int>, std::equal_to<int>, test_allocator<std::pair<const int,
-int>>>>::value);
 }
-*/
 
 #endif
+
+int main()
+{
+  std::cout << "BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES: "
+            << BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES << std::endl;
+
+#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+  map_tests<boost::unordered_map>();
+  map_tests<boost::unordered_multimap>();
+  set_tests<boost::unordered_set>();
+  set_tests<boost::unordered_multiset>();
+
+  return boost::report_errors();
+#endif
 }

From 530437c21b7f22fabb1977edb1c261e6664cd84a Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 10:26:59 -0800
Subject: [PATCH 3/8] Implement deduction guides for unordered_[multi]map

---
 include/boost/unordered/unordered_map.hpp | 159 ++++++++++++++--------
 1 file changed, 101 insertions(+), 58 deletions(-)

diff --git a/include/boost/unordered/unordered_map.hpp b/include/boost/unordered/unordered_map.hpp
index 4a060358..9d80d743 100644
--- a/include/boost/unordered/unordered_map.hpp
+++ b/include/boost/unordered/unordered_map.hpp
@@ -20,6 +20,7 @@
 #include <boost/move/move.hpp>
 #include <boost/type_traits/is_constructible.hpp>
 #include <boost/unordered/detail/map.hpp>
+#include <boost/unordered/detail/type_traits.hpp>
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 #include <initializer_list>
@@ -50,9 +51,9 @@ namespace boost {
       typedef K key_type;
       typedef T mapped_type;
       typedef std::pair<const K, T> value_type;
-      typedef H hasher;
-      typedef P key_equal;
-      typedef A allocator_type;
+      typedef typename boost::type_identity<H>::type hasher;
+      typedef typename boost::type_identity<P>::type key_equal;
+      typedef typename boost::type_identity<A>::type allocator_type;
 
     private:
       typedef boost::unordered::detail::map<A, K, T, H, P> types;
@@ -931,7 +932,7 @@ namespace boost {
       template <typename T>
       using iter_to_alloc_t =
         typename std::pair<iter_key_t<T> const, iter_val_t<T> >;
-    }
+    } // namespace detail
 
     template <class InputIterator,
       class Hash =
@@ -939,58 +940,80 @@ namespace boost {
       class Pred =
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
       class Allocator = std::allocator<
-        boost::unordered::detail::iter_to_alloc_t<InputIterator> > >
+        boost::unordered::detail::iter_to_alloc_t<InputIterator> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_map(InputIterator, InputIterator,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>, Hash, Pred,
         Allocator>;
 
-    template <class Key, class T, class Hash = boost::hash<Key>,
-      class Pred = std::equal_to<Key>,
-      class Allocator = std::allocator<std::pair<const Key, T> > >
-    unordered_map(std::initializer_list<std::pair<const Key, T> >,
+    template <class Key, class T,
+      class Hash = boost::hash<boost::remove_const_t<Key> >,
+      class Pred = std::equal_to<boost::remove_const_t<Key> >,
+      class Allocator = std::allocator<std::pair<const Key, T> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_map(std::initializer_list<std::pair<Key, T> >,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_map<Key, T, Hash, Pred, Allocator>;
+      -> unordered_map<boost::remove_const_t<Key>, T, Hash, Pred, Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_map(InputIterator, InputIterator, std::size_t, Allocator)
-      ->unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>,
         boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_map(InputIterator, InputIterator, Allocator)
-      ->unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>,
         boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class InputIterator, class Hash, class Allocator>
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_map(InputIterator, InputIterator, std::size_t, Hash, Allocator)
-      ->unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_map<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>, Hash,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class Key, class T, typename Allocator>
-    unordered_map(
-      std::initializer_list<std::pair<const Key, T> >, std::size_t, Allocator)
-      ->unordered_map<Key, T, boost::hash<Key>, std::equal_to<Key>, Allocator>;
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_map(std::initializer_list<std::pair<Key, T> >, std::size_t,
+      Allocator) -> unordered_map<boost::remove_const_t<Key>, T,
+      boost::hash<boost::remove_const_t<Key> >,
+      std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
-    template <class Key, class T, typename Allocator>
-    unordered_map(std::initializer_list<std::pair<const Key, T> >, Allocator)
-      ->unordered_map<Key, T, boost::hash<Key>, std::equal_to<Key>, Allocator>;
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_map(std::initializer_list<std::pair<Key, T> >, Allocator)
+      -> unordered_map<boost::remove_const_t<Key>, T,
+        boost::hash<boost::remove_const_t<Key> >,
+        std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
-    template <class Key, class T, class Hash, class Allocator>
-    unordered_map(std::initializer_list<std::pair<const Key, T> >, std::size_t,
-      Hash, Allocator)
-      ->unordered_map<Key, T, Hash, std::equal_to<Key>, Allocator>;
+    template <class Key, class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_map(std::initializer_list<std::pair<Key, T> >, std::size_t, Hash,
+      Allocator) -> unordered_map<boost::remove_const_t<Key>, T, Hash,
+      std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
 #endif
 
@@ -1007,9 +1030,9 @@ namespace boost {
       typedef K key_type;
       typedef T mapped_type;
       typedef std::pair<const K, T> value_type;
-      typedef H hasher;
-      typedef P key_equal;
-      typedef A allocator_type;
+      typedef typename boost::type_identity<H>::type hasher;
+      typedef typename boost::type_identity<P>::type key_equal;
+      typedef typename boost::type_identity<A>::type allocator_type;
 
     private:
       typedef boost::unordered::detail::map<A, K, T, H, P> types;
@@ -1612,62 +1635,82 @@ namespace boost {
       class Pred =
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
       class Allocator = std::allocator<
-        boost::unordered::detail::iter_to_alloc_t<InputIterator> > >
+        boost::unordered::detail::iter_to_alloc_t<InputIterator> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multimap(InputIterator, InputIterator,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>, Hash, Pred,
         Allocator>;
 
-    template <class Key, class T, class Hash = boost::hash<Key>,
-      class Pred = std::equal_to<Key>,
-      class Allocator = std::allocator<std::pair<const Key, T> > >
-    unordered_multimap(std::initializer_list<std::pair<const Key, T> >,
+    template <class Key, class T,
+      class Hash = boost::hash<boost::remove_const_t<Key> >,
+      class Pred = std::equal_to<boost::remove_const_t<Key> >,
+      class Allocator = std::allocator<std::pair<const Key, T> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_multimap(std::initializer_list<std::pair<Key, T> >,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_multimap<Key, T, Hash, Pred, Allocator>;
+      -> unordered_multimap<boost::remove_const_t<Key>, T, Hash, Pred,
+        Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multimap(InputIterator, InputIterator, std::size_t, Allocator)
-      ->unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>,
         boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multimap(InputIterator, InputIterator, Allocator)
-      ->unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>,
         boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class InputIterator, class Hash, class Allocator>
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multimap(
       InputIterator, InputIterator, std::size_t, Hash, Allocator)
-      ->unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
+      -> unordered_multimap<boost::unordered::detail::iter_key_t<InputIterator>,
         boost::unordered::detail::iter_val_t<InputIterator>, Hash,
         std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
         Allocator>;
 
-    template <class Key, class T, typename Allocator>
-    unordered_multimap(
-      std::initializer_list<std::pair<const Key, T> >, std::size_t, Allocator)
-      ->unordered_multimap<Key, T, boost::hash<Key>, std::equal_to<Key>,
-        Allocator>;
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_multimap(std::initializer_list<std::pair<Key, T> >, std::size_t,
+      Allocator) -> unordered_multimap<boost::remove_const_t<Key>, T,
+      boost::hash<boost::remove_const_t<Key> >,
+      std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
-    template <class Key, class T, typename Allocator>
-    unordered_multimap(
-      std::initializer_list<std::pair<const Key, T> >, Allocator)
-      ->unordered_multimap<Key, T, boost::hash<Key>, std::equal_to<Key>,
-        Allocator>;
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_multimap(std::initializer_list<std::pair<Key, T> >, Allocator)
+      -> unordered_multimap<boost::remove_const_t<Key>, T,
+        boost::hash<boost::remove_const_t<Key> >,
+        std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
-    template <class Key, class T, class Hash, class Allocator>
-    unordered_multimap(std::initializer_list<std::pair<const Key, T> >,
-      std::size_t, Hash, Allocator)
-      ->unordered_multimap<Key, T, Hash, std::equal_to<Key>, Allocator>;
+    template <class Key, class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_multimap(std::initializer_list<std::pair<Key, T> >, std::size_t,
+      Hash, Allocator) -> unordered_multimap<boost::remove_const_t<Key>, T,
+      Hash, std::equal_to<boost::remove_const_t<Key> >, Allocator>;
 
 #endif
 

From fd48672fd123f979972abd195bf238dde08a300a Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 12:55:54 -0800
Subject: [PATCH 4/8] Implement deduction guides for unordered_[multi]set

---
 include/boost/unordered/unordered_set.hpp | 79 ++++++++++++++++-------
 1 file changed, 55 insertions(+), 24 deletions(-)

diff --git a/include/boost/unordered/unordered_set.hpp b/include/boost/unordered/unordered_set.hpp
index b3e75134..7c8ce72c 100644
--- a/include/boost/unordered/unordered_set.hpp
+++ b/include/boost/unordered/unordered_set.hpp
@@ -19,6 +19,7 @@
 #include <boost/functional/hash.hpp>
 #include <boost/move/move.hpp>
 #include <boost/unordered/detail/set.hpp>
+#include <boost/unordered/detail/type_traits.hpp>
 
 #if !defined(BOOST_NO_CXX11_HDR_INITIALIZER_LIST)
 #include <initializer_list>
@@ -621,41 +622,56 @@ namespace boost {
       class Pred =
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
       class Allocator = std::allocator<
-        typename std::iterator_traits<InputIterator>::value_type> >
+        typename std::iterator_traits<InputIterator>::value_type>,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(InputIterator, InputIterator,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_set<typename std::iterator_traits<InputIterator>::value_type,
+      -> unordered_set<typename std::iterator_traits<InputIterator>::value_type,
         Hash, Pred, Allocator>;
 
     template <class T, class Hash = boost::hash<T>,
-      class Pred = std::equal_to<T>, class Allocator = std::allocator<T> >
+      class Pred = std::equal_to<T>, class Allocator = std::allocator<T>,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(std::initializer_list<T>,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_set<T, Hash, Pred, Allocator>;
+      -> unordered_set<T, Hash, Pred, Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(InputIterator, InputIterator, std::size_t, Allocator)
-      ->unordered_set<typename std::iterator_traits<InputIterator>::value_type,
+      -> unordered_set<typename std::iterator_traits<InputIterator>::value_type,
         boost::hash<typename std::iterator_traits<InputIterator>::value_type>,
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
         Allocator>;
 
-    template <class InputIterator, class Hash, class Allocator>
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(InputIterator, InputIterator, std::size_t, Hash, Allocator)
-      ->unordered_set<typename std::iterator_traits<InputIterator>::value_type,
+      -> unordered_set<typename std::iterator_traits<InputIterator>::value_type,
         Hash,
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
         Allocator>;
 
-    template <class T, class Allocator>
+    template <class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(std::initializer_list<T>, std::size_t, Allocator)
-      ->unordered_set<T, boost::hash<T>, std::equal_to<T>, Allocator>;
+      -> unordered_set<T, boost::hash<T>, std::equal_to<T>, Allocator>;
 
-    template <class T, class Hash, class Allocator>
+    template <class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_set(std::initializer_list<T>, std::size_t, Hash, Allocator)
-      ->unordered_set<T, Hash, std::equal_to<T>, Allocator>;
+      -> unordered_set<T, Hash, std::equal_to<T>, Allocator>;
 
 #endif
 
@@ -1233,44 +1249,59 @@ namespace boost {
       class Pred =
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
       class Allocator = std::allocator<
-        typename std::iterator_traits<InputIterator>::value_type> >
+        typename std::iterator_traits<InputIterator>::value_type>,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(InputIterator, InputIterator,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_multiset<
+      -> unordered_multiset<
         typename std::iterator_traits<InputIterator>::value_type, Hash, Pred,
         Allocator>;
 
     template <class T, class Hash = boost::hash<T>,
-      class Pred = std::equal_to<T>, class Allocator = std::allocator<T> >
+      class Pred = std::equal_to<T>, class Allocator = std::allocator<T>,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(std::initializer_list<T>,
       std::size_t = boost::unordered::detail::default_bucket_count,
       Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-      ->unordered_multiset<T, Hash, Pred, Allocator>;
+      -> unordered_multiset<T, Hash, Pred, Allocator>;
 
-    template <class InputIterator, class Allocator>
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(InputIterator, InputIterator, std::size_t, Allocator)
-      ->unordered_multiset<
+      -> unordered_multiset<
         typename std::iterator_traits<InputIterator>::value_type,
         boost::hash<typename std::iterator_traits<InputIterator>::value_type>,
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
         Allocator>;
 
-    template <class InputIterator, class Hash, class Allocator>
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(
       InputIterator, InputIterator, std::size_t, Hash, Allocator)
-      ->unordered_multiset<
+      -> unordered_multiset<
         typename std::iterator_traits<InputIterator>::value_type, Hash,
         std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
         Allocator>;
 
-    template <class T, class Allocator>
+    template <class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(std::initializer_list<T>, std::size_t, Allocator)
-      ->unordered_multiset<T, boost::hash<T>, std::equal_to<T>, Allocator>;
+      -> unordered_multiset<T, boost::hash<T>, std::equal_to<T>, Allocator>;
 
-    template <class T, class Hash, class Allocator>
+    template <class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
     unordered_multiset(std::initializer_list<T>, std::size_t, Hash, Allocator)
-      ->unordered_multiset<T, Hash, std::equal_to<T>, Allocator>;
+      -> unordered_multiset<T, Hash, std::equal_to<T>, Allocator>;
 
 #endif
 

From c37081b4a2aa5312a2cfa8ed42f87b15275ca5db Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 13:44:09 -0800
Subject: [PATCH 5/8] Add deduction tests for flat containers

---
 test/unordered/deduction_tests.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/test/unordered/deduction_tests.cpp b/test/unordered/deduction_tests.cpp
index e808f656..c979937f 100644
--- a/test/unordered/deduction_tests.cpp
+++ b/test/unordered/deduction_tests.cpp
@@ -11,6 +11,9 @@
 
 #if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
 
+#include <boost/unordered/unordered_flat_map.hpp>
+#include <boost/unordered/unordered_flat_set.hpp>
+
 struct hash_equals
 {
   template <typename T> bool operator()(T const& x) const
@@ -399,8 +402,10 @@ int main()
 #if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
   map_tests<boost::unordered_map>();
   map_tests<boost::unordered_multimap>();
+  map_tests<boost::unordered_flat_map>();
   set_tests<boost::unordered_set>();
   set_tests<boost::unordered_multiset>();
+  set_tests<boost::unordered_flat_set>();
 
   return boost::report_errors();
 #endif

From e2f43033196807b3e2365b1ba0d534e7d3e997c6 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 14:18:46 -0800
Subject: [PATCH 6/8] Add FOA-specific default bucket count for CTAD purposes

---
 include/boost/unordered/detail/foa.hpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index 29af58bf..0d48c911 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -72,6 +72,8 @@ namespace unordered{
 namespace detail{
 namespace foa{
 
+static const std::size_t default_bucket_count = 0;
+
 /* foa::table is an open-addressing hash table serving as the foundational core
  * of boost::unordered_flat_[map|set]. Its main internal design aspects are:
  * 

From 5b92827b68be590cd23995dc54de038e7a3642a8 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 13:44:21 -0800
Subject: [PATCH 7/8] Implement deduction guides for unordered_flat_map

---
 .../boost/unordered/unordered_flat_map.hpp    | 104 +++++++++++++++++-
 1 file changed, 101 insertions(+), 3 deletions(-)

diff --git a/include/boost/unordered/unordered_flat_map.hpp b/include/boost/unordered/unordered_flat_map.hpp
index 7ba2ba28..ac723ce9 100644
--- a/include/boost/unordered/unordered_flat_map.hpp
+++ b/include/boost/unordered/unordered_flat_map.hpp
@@ -76,9 +76,9 @@ namespace boost {
       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 hasher = typename boost::type_identity<Hash>::type;
+      using key_equal = typename boost::type_identity<KeyEqual>::type;
+      using allocator_type = typename boost::type_identity<Allocator>::type;
       using reference = value_type&;
       using const_reference = value_type const&;
       using pointer = typename boost::allocator_pointer<allocator_type>::type;
@@ -628,6 +628,104 @@ namespace boost {
 #pragma warning(pop) /* C4714 */
 #endif
 
+#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+
+    namespace detail {
+      template <typename T>
+      using iter_key_t =
+        typename std::iterator_traits<T>::value_type::first_type;
+      template <typename T>
+      using iter_val_t =
+        typename std::iterator_traits<T>::value_type::second_type;
+      template <typename T>
+      using iter_to_alloc_t =
+        typename std::pair<iter_key_t<T> const, iter_val_t<T> >;
+    } // namespace detail
+
+    template <class InputIterator,
+      class Hash =
+        boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
+      class Pred =
+        std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
+      class Allocator = std::allocator<
+        boost::unordered::detail::iter_to_alloc_t<InputIterator> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(InputIterator, InputIterator,
+      std::size_t = boost::unordered::detail::foa::default_bucket_count,
+      Hash = Hash(), Pred = Pred(), Allocator = Allocator())
+      -> unordered_flat_map<boost::unordered::detail::iter_key_t<InputIterator>,
+        boost::unordered::detail::iter_val_t<InputIterator>, Hash, Pred,
+        Allocator>;
+
+    template <class Key, class T,
+      class Hash = boost::hash<boost::remove_const_t<Key> >,
+      class Pred = std::equal_to<boost::remove_const_t<Key> >,
+      class Allocator = std::allocator<std::pair<const Key, T> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(std::initializer_list<std::pair<Key, T> >,
+      std::size_t = boost::unordered::detail::foa::default_bucket_count,
+      Hash = Hash(), Pred = Pred(), Allocator = Allocator())
+      -> unordered_flat_map<boost::remove_const_t<Key>, T, Hash, Pred,
+        Allocator>;
+
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(InputIterator, InputIterator, std::size_t, Allocator)
+      -> unordered_flat_map<boost::unordered::detail::iter_key_t<InputIterator>,
+        boost::unordered::detail::iter_val_t<InputIterator>,
+        boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
+        std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
+        Allocator>;
+
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(InputIterator, InputIterator, Allocator)
+      -> unordered_flat_map<boost::unordered::detail::iter_key_t<InputIterator>,
+        boost::unordered::detail::iter_val_t<InputIterator>,
+        boost::hash<boost::unordered::detail::iter_key_t<InputIterator> >,
+        std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
+        Allocator>;
+
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(
+      InputIterator, InputIterator, std::size_t, Hash, Allocator)
+      -> unordered_flat_map<boost::unordered::detail::iter_key_t<InputIterator>,
+        boost::unordered::detail::iter_val_t<InputIterator>, Hash,
+        std::equal_to<boost::unordered::detail::iter_key_t<InputIterator> >,
+        Allocator>;
+
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(std::initializer_list<std::pair<Key, T> >, std::size_t,
+      Allocator) -> unordered_flat_map<boost::remove_const_t<Key>, T,
+      boost::hash<boost::remove_const_t<Key> >,
+      std::equal_to<boost::remove_const_t<Key> >, Allocator>;
+
+    template <class Key, class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(std::initializer_list<std::pair<Key, T> >, Allocator)
+      -> unordered_flat_map<boost::remove_const_t<Key>, T,
+        boost::hash<boost::remove_const_t<Key> >,
+        std::equal_to<boost::remove_const_t<Key> >, Allocator>;
+
+    template <class Key, class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_map(std::initializer_list<std::pair<Key, T> >, std::size_t,
+      Hash, Allocator) -> unordered_flat_map<boost::remove_const_t<Key>, T,
+      Hash, std::equal_to<boost::remove_const_t<Key> >, Allocator>;
+#endif
+
   } // namespace unordered
 } // namespace boost
 

From 2102031b93aaa207fec6d62f7e8ebcc7c5280cee Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 7 Nov 2022 13:44:33 -0800
Subject: [PATCH 8/8] Implement deduction guides for unordered_flat_set

---
 .../boost/unordered/unordered_flat_set.hpp    | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/include/boost/unordered/unordered_flat_set.hpp b/include/boost/unordered/unordered_flat_set.hpp
index ef96d4e1..b1291caf 100644
--- a/include/boost/unordered/unordered_flat_set.hpp
+++ b/include/boost/unordered/unordered_flat_set.hpp
@@ -503,6 +503,68 @@ namespace boost {
 #pragma warning(pop) /* C4714 */
 #endif
 
+#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
+    template <class InputIterator,
+      class Hash =
+        boost::hash<typename std::iterator_traits<InputIterator>::value_type>,
+      class Pred =
+        std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
+      class Allocator = std::allocator<
+        typename std::iterator_traits<InputIterator>::value_type>,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(InputIterator, InputIterator,
+      std::size_t = boost::unordered::detail::foa::default_bucket_count,
+      Hash = Hash(), Pred = Pred(), Allocator = Allocator())
+      -> unordered_flat_set<
+        typename std::iterator_traits<InputIterator>::value_type, Hash, Pred,
+        Allocator>;
+
+    template <class T, class Hash = boost::hash<T>,
+      class Pred = std::equal_to<T>, class Allocator = std::allocator<T>,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_pred_v<Pred> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(std::initializer_list<T>,
+      std::size_t = boost::unordered::detail::foa::default_bucket_count,
+      Hash = Hash(), Pred = Pred(), Allocator = Allocator())
+      -> unordered_flat_set<T, Hash, Pred, Allocator>;
+
+    template <class InputIterator, class Allocator,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(InputIterator, InputIterator, std::size_t, Allocator)
+      -> unordered_flat_set<
+        typename std::iterator_traits<InputIterator>::value_type,
+        boost::hash<typename std::iterator_traits<InputIterator>::value_type>,
+        std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
+        Allocator>;
+
+    template <class InputIterator, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_input_iterator_v<InputIterator> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(
+      InputIterator, InputIterator, std::size_t, Hash, Allocator)
+      -> unordered_flat_set<
+        typename std::iterator_traits<InputIterator>::value_type, Hash,
+        std::equal_to<typename std::iterator_traits<InputIterator>::value_type>,
+        Allocator>;
+
+    template <class T, class Allocator,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(std::initializer_list<T>, std::size_t, Allocator)
+      -> unordered_flat_set<T, boost::hash<T>, std::equal_to<T>, Allocator>;
+
+    template <class T, class Hash, class Allocator,
+      class = boost::enable_if_t<detail::is_hash_v<Hash> >,
+      class = boost::enable_if_t<detail::is_allocator_v<Allocator> > >
+    unordered_flat_set(std::initializer_list<T>, std::size_t, Hash, Allocator)
+      -> unordered_flat_set<T, Hash, std::equal_to<T>, Allocator>;
+#endif
+
   } // namespace unordered
 } // namespace boost