From 4f829b91320edcf8ee9ace3b0836a1f2ba479447 Mon Sep 17 00:00:00 2001
From: andreyasu <andreyasu@bk.ru>
Date: Thu, 22 Aug 2019 20:31:41 +0300
Subject: [PATCH] Fix bug when copying an empy map with the copy constructor
 (#9)

---
 include/tsl/sparse_hash.h  |  2 +-
 tests/sparse_map_tests.cpp | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/tsl/sparse_hash.h b/include/tsl/sparse_hash.h
index d7c9793..b96f61c 100644
--- a/include/tsl/sparse_hash.h
+++ b/include/tsl/sparse_hash.h
@@ -1154,7 +1154,7 @@ class sparse_hash: private Allocator, private Hash, private KeyEqual, private Gr
                     m_max_load_factor(other.m_max_load_factor)
     {
         copy_buckets_from(other),
-        m_sparse_buckets = m_sparse_buckets_data.data();
+        m_sparse_buckets = m_sparse_buckets_data.empty() ? static_empty_sparse_bucket_ptr() : m_sparse_buckets_data.data();
     }
     
     sparse_hash(sparse_hash&& other) noexcept(std::is_nothrow_move_constructible<Allocator>::value &&
diff --git a/tests/sparse_map_tests.cpp b/tests/sparse_map_tests.cpp
index 1f5d78c..b7bcdbe 100644
--- a/tests/sparse_map_tests.cpp
+++ b/tests/sparse_map_tests.cpp
@@ -845,6 +845,28 @@ BOOST_AUTO_TEST_CASE(test_copy_constructor_and_operator) {
     BOOST_CHECK(map_copy == map_copy3);
 }
 
+BOOST_AUTO_TEST_CASE(test_copy_constructor_empty) {
+    tsl::sparse_map<std::string, int> map(0);
+    tsl::sparse_map<std::string, int> map_copy(map);
+    
+    BOOST_CHECK(map.empty());
+    BOOST_CHECK(map_copy.empty());
+    
+    BOOST_CHECK(map.find("") == map.end());
+    BOOST_CHECK(map_copy.find("") == map_copy.end());
+}
+
+BOOST_AUTO_TEST_CASE(test_copy_operator_empty) {
+    tsl::sparse_map<std::string, int> map(0);
+    tsl::sparse_map<std::string, int> map_copy(16);
+    map_copy = map;
+    
+    BOOST_CHECK(map.empty());
+    BOOST_CHECK(map_copy.empty());
+    
+    BOOST_CHECK(map.find("") == map.end());
+    BOOST_CHECK(map_copy.find("") == map_copy.end());
+}
 
 /**
  * at