compressed_pair:

* disable structured binding support for clang 6
* avoid using structured binding with compressed pair in the codebase

src/entt/core/compressed_pair.hpp

@@ -266,6 +266,8 @@ inline void swap(compressed_pair<First, Second> &lhs, compressed_pair<First, Sec
 
 
 namespace std {
+// disable structured binding support for clang 6, it messes when specializing tuple_size
+#if !defined __clang_major__ || __clang_major__ > 6
     template<typename First, typename Second>
     struct tuple_size<entt::compressed_pair<First, Second>>: integral_constant<size_t, 2u> {};
 
@@ -273,6 +275,7 @@ namespace std {
     struct tuple_element<Index, entt::compressed_pair<First, Second>>: conditional<Index == 0u, First, Second> {
         static_assert(Index < 2u, "Index out of bounds");
     };
+#endif
 }
 
 

src/entt/entity/sparse_set.hpp

@@ -200,7 +200,8 @@ class basic_sparse_set {
     }
 
     void resize_packed_array(const std::size_t req) {
-        auto &&[allocator, len] = reserved;
+        auto &allocator = reserved.first();
+        auto &len = reserved.second();
         ENTT_ASSERT((req != len) && !(req < count), "Invalid request");
         const auto mem = alloc_traits::allocate(allocator, req);
 
@@ -217,7 +218,8 @@ class basic_sparse_set {
     }
 
     void release_memory() {
-        auto &&[allocator, len] = reserved;
+        auto &allocator = reserved.first();
+        auto &len = reserved.second();
 
         if(packed_array) {
             std::destroy(packed_array, packed_array + len);

src/entt/entity/storage.hpp

@@ -184,7 +184,8 @@ class basic_storage: public basic_sparse_set<Entity, typename std::allocator_tra
             // no-throw stable erase iteration
             base_type::clear();
 
-            auto &&[allocator, len] = bucket;
+            auto &allocator = bucket.first();
+            auto &len = bucket.second();
             alloc_ptr allocator_ptr{allocator};
 
             for(size_type pos{}; pos < len; ++pos) {
@@ -198,7 +199,8 @@ class basic_storage: public basic_sparse_set<Entity, typename std::allocator_tra
 
     void assure_at_least(const std::size_t pos) {
         if(const auto idx = page(pos); !(idx < bucket.second())) {
-            auto &&[allocator, len] = bucket;
+            auto &allocator = bucket.first();
+            auto &len = bucket.second();
             alloc_ptr allocator_ptr{allocator};
 
             const size_type sz = idx + 1u;
@@ -232,7 +234,8 @@ class basic_storage: public basic_sparse_set<Entity, typename std::allocator_tra
 
     void release_unused_pages() {
         if(const auto length = base_type::size() / packed_page; length < bucket.second()) {
-            auto &&[allocator, len] = bucket;
+            auto &allocator = bucket.first();
+            auto &len = bucket.second();
             alloc_ptr allocator_ptr{allocator};
 
             const auto mem = alloc_ptr_traits::allocate(allocator_ptr, length);