storage: fix cross range-erase can break when using built-in iterators (close #914)

src/entt/entity/storage.hpp

@@ -333,9 +333,11 @@ protected:
      */
     void swap_and_pop(typename underlying_type::basic_iterator first, typename underlying_type::basic_iterator last) override {
         for(; first != last; ++first) {
+            // cannot use first::index() because it would break with cross iterators
+            const auto pos = index(*first);
             auto &elem = element_at(base_type::size() - 1u);
             // destroying on exit allows reentrant destructors
-            [[maybe_unused]] auto unused = std::exchange(element_at(static_cast<size_type>(first.index())), std::move(elem));
+            [[maybe_unused]] auto unused = std::exchange(element_at(pos), std::move(elem));
             std::destroy_at(std::addressof(elem));
             base_type::swap_and_pop(first, first + 1u);
         }
@@ -348,8 +350,10 @@ protected:
      */
     void in_place_pop(typename underlying_type::basic_iterator first, typename underlying_type::basic_iterator last) override {
         for(; first != last; ++first) {
+            // cannot use first::index() because it would break with cross iterators
+            const auto pos = index(*first);
             base_type::in_place_pop(first, first + 1u);
-            std::destroy_at(std::addressof(element_at(static_cast<size_type>(first.index()))));
+            std::destroy_at(std::addressof(element_at(pos)));
         }
     }
 

test/entt/entity/storage.cpp

@@ -345,6 +345,21 @@ TEST(Storage, Erase) {
     ASSERT_EQ(*pool.begin(), 1);
 }
 
+TEST(Storage, CrossErase) {
+    entt::sparse_set set;
+    entt::storage<int> pool;
+    entt::entity entities[2u]{entt::entity{3}, entt::entity{42}};
+
+    pool.emplace(entities[0u], 3);
+    pool.emplace(entities[1u], 42);
+    set.emplace(entities[1u]);
+    pool.erase(set.begin(), set.end());
+
+    ASSERT_TRUE(pool.contains(entities[0u]));
+    ASSERT_FALSE(pool.contains(entities[1u]));
+    ASSERT_EQ(pool.raw()[0u][0u], 3);
+}
+
 TEST(Storage, StableErase) {
     entt::storage<stable_type> pool;
     entt::entity entities[3u]{entt::entity{3}, entt::entity{42}, entt::entity{9}};
@@ -439,6 +454,21 @@ TEST(Storage, StableErase) {
     ASSERT_EQ(pool.get(entities[2u]).value, 1);
 }
 
+TEST(Storage, CrossStableErase) {
+    entt::sparse_set set;
+    entt::storage<stable_type> pool;
+    entt::entity entities[2u]{entt::entity{3}, entt::entity{42}};
+
+    pool.emplace(entities[0u], 3);
+    pool.emplace(entities[1u], 42);
+    set.emplace(entities[1u]);
+    pool.erase(set.begin(), set.end());
+
+    ASSERT_TRUE(pool.contains(entities[0u]));
+    ASSERT_FALSE(pool.contains(entities[1u]));
+    ASSERT_EQ(pool.raw()[0u][0u].value, 3);
+}
+
 TEST(Storage, Remove) {
     entt::storage<int> pool;
     entt::entity entities[3u]{entt::entity{3}, entt::entity{42}, entt::entity{9}};
@@ -473,6 +503,21 @@ TEST(Storage, Remove) {
     ASSERT_EQ(*pool.begin(), 1);
 }
 
+TEST(Storage, CrossRemove) {
+    entt::sparse_set set;
+    entt::storage<int> pool;
+    entt::entity entities[2u]{entt::entity{3}, entt::entity{42}};
+
+    pool.emplace(entities[0u], 3);
+    pool.emplace(entities[1u], 42);
+    set.emplace(entities[1u]);
+    pool.remove(set.begin(), set.end());
+
+    ASSERT_TRUE(pool.contains(entities[0u]));
+    ASSERT_FALSE(pool.contains(entities[1u]));
+    ASSERT_EQ(pool.raw()[0u][0u], 3);
+}
+
 TEST(Storage, StableRemove) {
     entt::storage<stable_type> pool;
     entt::entity entities[3u]{entt::entity{3}, entt::entity{42}, entt::entity{9}};
@@ -570,6 +615,21 @@ TEST(Storage, StableRemove) {
     ASSERT_EQ(pool.get(entities[2u]).value, 1);
 }
 
+TEST(Storage, CrossStableRemove) {
+    entt::sparse_set set;
+    entt::storage<stable_type> pool;
+    entt::entity entities[2u]{entt::entity{3}, entt::entity{42}};
+
+    pool.emplace(entities[0u], 3);
+    pool.emplace(entities[1u], 42);
+    set.emplace(entities[1u]);
+    pool.remove(set.begin(), set.end());
+
+    ASSERT_TRUE(pool.contains(entities[0u]));
+    ASSERT_FALSE(pool.contains(entities[1u]));
+    ASSERT_EQ(pool.raw()[0u][0u].value, 3);
+}
+
 TEST(Storage, TypeFromBase) {
     entt::storage<int> pool;
     entt::sparse_set &base = pool;