From 4f1897e8647b4cf70a18bd0ca90fa96dd22f6474 Mon Sep 17 00:00:00 2001
From: skypjack <michele.caini@gmail.com>
Date: Wed, 1 Apr 2026 09:31:13 +0200
Subject: [PATCH] stl: std::declval

---
 src/entt/container/dense_map.hpp | 8 ++++----
 src/entt/container/table.hpp     | 2 +-
 src/entt/core/tuple.hpp          | 4 ++--
 src/entt/core/type_traits.hpp    | 6 +++---
 src/entt/entity/group.hpp        | 6 +++---
 src/entt/entity/handle.hpp       | 2 +-
 src/entt/entity/registry.hpp     | 2 +-
 src/entt/entity/storage.hpp      | 2 +-
 src/entt/entity/view.hpp         | 8 ++++----
 src/entt/meta/container.hpp      | 2 +-
 src/entt/meta/meta.hpp           | 4 ++--
 src/entt/meta/utility.hpp        | 2 +-
 src/entt/poly/poly.hpp           | 2 +-
 src/entt/signal/delegate.hpp     | 2 +-
 src/entt/stl/utility.hpp         | 1 +
 15 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/src/entt/container/dense_map.hpp b/src/entt/container/dense_map.hpp
index 1ab1cbff4..803a63b4c 100644
--- a/src/entt/container/dense_map.hpp
+++ b/src/entt/container/dense_map.hpp
@@ -61,8 +61,8 @@ class dense_map_iterator final {
     friend class dense_map_iterator;
 
     static_assert(std::is_pointer_v<It>, "Not a pointer type");
-    using first_type = decltype(std::as_const(std::declval<It>()->element.first));
-    using second_type = decltype((std::declval<It>()->element.second));
+    using first_type = decltype(std::as_const(stl::declval<It>()->element.first));
+    using second_type = decltype((stl::declval<It>()->element.second));
 
 public:
     using value_type = std::pair<first_type, second_type>;
@@ -156,8 +156,8 @@ class dense_map_local_iterator final {
     friend class dense_map_local_iterator;
 
     static_assert(std::is_pointer_v<It>, "Not a pointer type");
-    using first_type = decltype(std::as_const(std::declval<It>()->element.first));
-    using second_type = decltype((std::declval<It>()->element.second));
+    using first_type = decltype(std::as_const(stl::declval<It>()->element.first));
+    using second_type = decltype((stl::declval<It>()->element.second));
 
 public:
     using value_type = std::pair<first_type, second_type>;
diff --git a/src/entt/container/table.hpp b/src/entt/container/table.hpp
index 49a451292..eed5c5c66 100644
--- a/src/entt/container/table.hpp
+++ b/src/entt/container/table.hpp
@@ -21,7 +21,7 @@ class table_iterator {
     friend class table_iterator;
 
 public:
-    using value_type = decltype(stl::forward_as_tuple(*std::declval<It>()...));
+    using value_type = decltype(stl::forward_as_tuple(*stl::declval<It>()...));
     using pointer = input_iterator_pointer<value_type>;
     using reference = value_type;
     using difference_type = std::ptrdiff_t;
diff --git a/src/entt/core/tuple.hpp b/src/entt/core/tuple.hpp
index 994009243..d19f8c600 100644
--- a/src/entt/core/tuple.hpp
+++ b/src/entt/core/tuple.hpp
@@ -67,13 +67,13 @@ struct forward_apply: private Func {
      * @return Return value of the underlying function, if any.
      */
     template<typename Type>
-    constexpr decltype(auto) operator()(Type &&args) noexcept(noexcept(stl::apply(std::declval<Func &>(), args))) {
+    constexpr decltype(auto) operator()(Type &&args) noexcept(noexcept(stl::apply(stl::declval<Func &>(), args))) {
         return stl::apply(static_cast<Func &>(*this), std::forward<Type>(args));
     }
 
     /*! @copydoc operator()() */
     template<typename Type>
-    constexpr decltype(auto) operator()(Type &&args) const noexcept(noexcept(stl::apply(std::declval<const Func &>(), args))) {
+    constexpr decltype(auto) operator()(Type &&args) const noexcept(noexcept(stl::apply(stl::declval<const Func &>(), args))) {
         return stl::apply(static_cast<const Func &>(*this), std::forward<Type>(args));
     }
 };
diff --git a/src/entt/core/type_traits.hpp b/src/entt/core/type_traits.hpp
index b621c0df0..3b19de300 100644
--- a/src/entt/core/type_traits.hpp
+++ b/src/entt/core/type_traits.hpp
@@ -750,7 +750,7 @@ template<typename>
 }
 
 template<typename Type>
-[[nodiscard]] ENTT_CONSTEVAL auto maybe_equality_comparable(int) -> decltype(std::declval<Type>() == std::declval<Type>()) {
+[[nodiscard]] ENTT_CONSTEVAL auto maybe_equality_comparable(int) -> decltype(stl::declval<Type>() == stl::declval<Type>()) {
     return true;
 }
 
@@ -844,7 +844,7 @@ class member_class {
 
 public:
     /*! @brief The class of the given non-static member object or function. */
-    using type = std::remove_pointer_t<decltype(clazz(std::declval<Member>()))>;
+    using type = std::remove_pointer_t<decltype(clazz(stl::declval<Member>()))>;
 };
 
 /**
@@ -878,7 +878,7 @@ class nth_argument {
 
 public:
     /*! @brief N-th argument of the _callable_ type. */
-    using type = type_list_element_t<Index, decltype(pick_up(std::declval<Candidate>()))>;
+    using type = type_list_element_t<Index, decltype(pick_up(stl::declval<Candidate>()))>;
 };
 
 /**
diff --git a/src/entt/entity/group.hpp b/src/entt/entity/group.hpp
index 71a23a138..02685dc50 100644
--- a/src/entt/entity/group.hpp
+++ b/src/entt/entity/group.hpp
@@ -38,7 +38,7 @@ class extended_group_iterator<It, owned_t<Owned...>, get_t<Get...>> {
 
 public:
     using iterator_type = It;
-    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*std::declval<It>()), std::declval<Owned>().get_as_tuple({})..., std::declval<Get>().get_as_tuple({})...));
+    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*stl::declval<It>()), stl::declval<Owned>().get_as_tuple({})..., stl::declval<Get>().get_as_tuple({})...));
     using pointer = input_iterator_pointer<value_type>;
     using reference = value_type;
     using difference_type = std::ptrdiff_t;
@@ -536,7 +536,7 @@ public:
     template<typename Func>
     void each(Func func) const {
         for(const auto entt: *this) {
-            if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, std::declval<basic_group>().get({})))>) {
+            if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, stl::declval<basic_group>().get({})))>) {
                 stl::apply(func, stl::tuple_cat(stl::make_tuple(entt), get(entt)));
             } else {
                 stl::apply(func, get(entt));
@@ -935,7 +935,7 @@ public:
     template<typename Func>
     void each(Func func) const {
         for(auto args: each()) {
-            if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, std::declval<basic_group>().get({})))>) {
+            if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, stl::declval<basic_group>().get({})))>) {
                 stl::apply(func, args);
             } else {
                 stl::apply([&func](auto, auto &&...less) { func(std::forward<decltype(less)>(less)...); }, args);
diff --git a/src/entt/entity/handle.hpp b/src/entt/entity/handle.hpp
index bd365e8d1..8d0050aa9 100644
--- a/src/entt/entity/handle.hpp
+++ b/src/entt/entity/handle.hpp
@@ -105,7 +105,7 @@ public:
     /*! @brief Unsigned integer type. */
     using size_type = std::size_t;
     /*! @brief Iterable handle type. */
-    using iterable = iterable_adaptor<internal::handle_storage_iterator<typename decltype(std::declval<registry_type>().storage())::iterator>>;
+    using iterable = iterable_adaptor<internal::handle_storage_iterator<typename decltype(stl::declval<registry_type>().storage())::iterator>>;
 
     /*! @brief Constructs an invalid handle. */
     basic_handle() noexcept
diff --git a/src/entt/entity/registry.hpp b/src/entt/entity/registry.hpp
index 536ec0304..b8be6c3f3 100644
--- a/src/entt/entity/registry.hpp
+++ b/src/entt/entity/registry.hpp
@@ -41,7 +41,7 @@ class registry_storage_iterator final {
     template<typename>
     friend class registry_storage_iterator;
 
-    using mapped_type = std::remove_reference_t<decltype(std::declval<It>()->second)>;
+    using mapped_type = std::remove_reference_t<decltype(stl::declval<It>()->second)>;
 
 public:
     using value_type = std::pair<id_type, constness_as_t<typename mapped_type::element_type, mapped_type> &>;
diff --git a/src/entt/entity/storage.hpp b/src/entt/entity/storage.hpp
index b51cf7ec6..a945148a1 100644
--- a/src/entt/entity/storage.hpp
+++ b/src/entt/entity/storage.hpp
@@ -139,7 +139,7 @@ class extended_storage_iterator final {
 
 public:
     using iterator_type = It;
-    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*std::declval<It>()), stl::forward_as_tuple(*std::declval<Other>()...)));
+    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*stl::declval<It>()), stl::forward_as_tuple(*stl::declval<Other>()...)));
     using pointer = input_iterator_pointer<value_type>;
     using reference = value_type;
     using difference_type = std::ptrdiff_t;
diff --git a/src/entt/entity/view.hpp b/src/entt/entity/view.hpp
index 6eaed680f..37b4d6049 100644
--- a/src/entt/entity/view.hpp
+++ b/src/entt/entity/view.hpp
@@ -131,7 +131,7 @@ private:
 template<typename It, typename... Get>
 struct extended_view_iterator final {
     using iterator_type = It;
-    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*std::declval<It>()), std::declval<Get>().get_as_tuple({})...));
+    using value_type = decltype(stl::tuple_cat(stl::make_tuple(*stl::declval<It>()), stl::declval<Get>().get_as_tuple({})...));
     using pointer = input_iterator_pointer<value_type>;
     using reference = value_type;
     using difference_type = std::ptrdiff_t;
@@ -430,7 +430,7 @@ class basic_view<get_t<Get...>, exclude_t<Exclude...>>
     void each(Func func, std::index_sequence<Index...>) const {
         for(const auto curr: storage<Curr>()->each()) {
             if(const auto entt = std::get<0>(curr); (!internal::tombstone_check_v<Get...> || (entt != tombstone)) && ((Curr == Index || base_type::pool_at(Index)->contains(entt)) && ...) && base_type::none_of(entt)) {
-                if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, std::declval<basic_view>().get({})))>) {
+                if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, stl::declval<basic_view>().get({})))>) {
                     stl::apply(func, stl::tuple_cat(stl::make_tuple(entt), dispatch_get<Curr, Index>(curr)...));
                 } else {
                     stl::apply(func, stl::tuple_cat(dispatch_get<Curr, Index>(curr)...));
@@ -918,7 +918,7 @@ public:
     /*! @brief Reverse iterator type. */
     using reverse_iterator = base_type::reverse_iterator;
     /*! @brief Iterable view type. */
-    using iterable = std::conditional_t<Get::storage_policy == deletion_policy::in_place, iterable_adaptor<internal::extended_view_iterator<iterator, Get>>, decltype(std::declval<Get>().each())>;
+    using iterable = std::conditional_t<Get::storage_policy == deletion_policy::in_place, iterable_adaptor<internal::extended_view_iterator<iterator, Get>>, decltype(stl::declval<Get>().each())>;
 
     /*! @brief Default constructor to use to create empty, invalid views. */
     basic_view() noexcept
@@ -1053,7 +1053,7 @@ public:
      */
     template<typename Func>
     void each(Func func) const {
-        if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, std::declval<basic_view>().get({})))>) {
+        if constexpr(is_applicable_v<Func, decltype(stl::tuple_cat(stl::tuple<entity_type>{}, stl::declval<basic_view>().get({})))>) {
             for(const auto pack: each()) {
                 stl::apply(func, pack);
             }
diff --git a/src/entt/meta/container.hpp b/src/entt/meta/container.hpp
index 7cde20cfe..3ba37d923 100644
--- a/src/entt/meta/container.hpp
+++ b/src/entt/meta/container.hpp
@@ -49,7 +49,7 @@ concept meta_associative_container_like = requires(Type value) {
     requires entt::stl::forward_iterator<typename Type::iterator>;
     { value.begin() } -> std::same_as<typename Type::iterator>;
     { value.end() } -> std::same_as<typename Type::iterator>;
-    value.find(std::declval<typename Type::key_type>());
+    value.find(stl::declval<typename Type::key_type>());
 };
 
 } // namespace internal
diff --git a/src/entt/meta/meta.hpp b/src/entt/meta/meta.hpp
index 9f680f3fc..1cf777584 100644
--- a/src/entt/meta/meta.hpp
+++ b/src/entt/meta/meta.hpp
@@ -187,10 +187,10 @@ class meta_any {
                 if constexpr(!std::is_void_v<std::remove_const_t<typename std::pointer_traits<Type>::element_type>>) {
                     if constexpr(std::is_constructible_v<bool, Type>) {
                         if(const auto &pointer_like = any_cast<const Type &>(value.storage); pointer_like) {
-                            static_cast<meta_any *>(other)->emplace<decltype(adl_meta_pointer_like<Type>::dereference(std::declval<const Type &>()))>(adl_meta_pointer_like<Type>::dereference(pointer_like));
+                            static_cast<meta_any *>(other)->emplace<decltype(adl_meta_pointer_like<Type>::dereference(stl::declval<const Type &>()))>(adl_meta_pointer_like<Type>::dereference(pointer_like));
                         }
                     } else {
-                        static_cast<meta_any *>(other)->emplace<decltype(adl_meta_pointer_like<Type>::dereference(std::declval<const Type &>()))>(adl_meta_pointer_like<Type>::dereference(any_cast<const Type &>(value.storage)));
+                        static_cast<meta_any *>(other)->emplace<decltype(adl_meta_pointer_like<Type>::dereference(stl::declval<const Type &>()))>(adl_meta_pointer_like<Type>::dereference(any_cast<const Type &>(value.storage)));
                     }
                 }
             }
diff --git a/src/entt/meta/utility.hpp b/src/entt/meta/utility.hpp
index 5dd16e0ce..55b47e857 100644
--- a/src/entt/meta/utility.hpp
+++ b/src/entt/meta/utility.hpp
@@ -141,7 +141,7 @@ class meta_function_helper {
 
 public:
     /*! @brief The meta function descriptor of the given function. */
-    using type = decltype(get_rid_of_noexcept(std::declval<Candidate>()));
+    using type = decltype(get_rid_of_noexcept(stl::declval<Candidate>()));
 };
 
 /**
diff --git a/src/entt/poly/poly.hpp b/src/entt/poly/poly.hpp
index 77df7359c..a6b8a41e3 100644
--- a/src/entt/poly/poly.hpp
+++ b/src/entt/poly/poly.hpp
@@ -77,7 +77,7 @@ class poly_vtable {
         if constexpr(sizeof...(Func) == 0u) {
             return decltype(make_vtable(typename Concept::template impl<inspector>{})){};
         } else if constexpr((std::is_function_v<Func> && ...)) {
-            return decltype(stl::make_tuple(vtable_entry(std::declval<Func inspector::*>())...)){};
+            return decltype(stl::make_tuple(vtable_entry(stl::declval<Func inspector::*>())...)){};
         }
     }
 
diff --git a/src/entt/signal/delegate.hpp b/src/entt/signal/delegate.hpp
index f830c7303..adc6667d7 100644
--- a/src/entt/signal/delegate.hpp
+++ b/src/entt/signal/delegate.hpp
@@ -32,7 +32,7 @@ requires stl::is_member_object_pointer_v<Type Class::*>
 auto function_pointer(Type Class::*, Other &&...) -> Type (*)();
 
 template<typename... Type>
-using function_pointer_t = decltype(function_pointer(std::declval<Type>()...));
+using function_pointer_t = decltype(function_pointer(stl::declval<Type>()...));
 
 template<typename... Class, typename Ret, typename... Args>
 [[nodiscard]] ENTT_CONSTEVAL auto index_sequence_for(Ret (*)(Args...)) {
diff --git a/src/entt/stl/utility.hpp b/src/entt/stl/utility.hpp
index f2265c09d..2a0960609 100644
--- a/src/entt/stl/utility.hpp
+++ b/src/entt/stl/utility.hpp
@@ -6,6 +6,7 @@
 /*! @cond ENTT_INTERNAL */
 namespace entt::stl {
 
+using std::declval;
 using std::exchange;
 
 } // namespace entt::stl