From 596e1ce135de1bc03e1a05cee63176ccedaab08b Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Thu, 13 Jan 2022 09:15:52 -0800
Subject: [PATCH 1/2] Add tests for `unordered_multiset::contains()`

---
 test/unordered/contains_tests.cpp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/test/unordered/contains_tests.cpp b/test/unordered/contains_tests.cpp
index 45bc59d9..e6123959 100644
--- a/test/unordered/contains_tests.cpp
+++ b/test/unordered/contains_tests.cpp
@@ -246,6 +246,25 @@ void test_set()
   test_set_non_transparent_contains<non_transparent_set3>();
 }
 
+void test_multiset()
+{
+  typedef boost::unordered_multiset<key, transparent_hasher,
+    transparent_key_equal>
+    transparent_multiset;
+
+  typedef boost::unordered_multiset<key, transparent_hasher, key_equal>
+    non_transparent_multiset1;
+  typedef boost::unordered_multiset<key, hasher, transparent_key_equal>
+    non_transparent_multiset2;
+  typedef boost::unordered_multiset<key, hasher, key_equal>
+    non_transparent_multiset3;
+
+  test_set_transparent_contains<transparent_multiset>();
+  test_set_non_transparent_contains<non_transparent_multiset1>();
+  test_set_non_transparent_contains<non_transparent_multiset2>();
+  test_set_non_transparent_contains<non_transparent_multiset3>();
+}
+
 UNORDERED_AUTO_TEST (contains) {
   test_map();
   test_multimap();

From 97734fd8954753ee2b5c383f31a2f8e76240e5ff Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Thu, 13 Jan 2022 09:16:03 -0800
Subject: [PATCH 2/2] Implement `unordered_multiset::contains()`

---
 include/boost/unordered/unordered_set.hpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/boost/unordered/unordered_set.hpp b/include/boost/unordered/unordered_set.hpp
index 0210056d..d6f1abc3 100644
--- a/include/boost/unordered/unordered_set.hpp
+++ b/include/boost/unordered/unordered_set.hpp
@@ -1125,6 +1125,23 @@ namespace boost {
       const_iterator find(CompatibleKey const&, CompatibleHash const&,
         CompatiblePredicate const&) const;
 
+      bool contains(const key_type& k) const
+      {
+        return table_.find_node_impl(
+          table::policy::apply_hash(this->hash_function(), k), k,
+          this->key_eq());
+      }
+
+      template <class Key>
+      typename boost::enable_if_c<detail::are_transparent<Key, H, P>::value,
+        bool>::type
+      contains(const Key& k) const
+      {
+        return table_.find_node_impl(
+          table::policy::apply_hash(this->hash_function(), k), k,
+          this->key_eq());
+      }
+
       size_type count(const key_type&) const;
 
       template <class Key>