meta_any: no void vtable by default

src/entt/meta/meta.hpp

@@ -316,7 +316,7 @@ public:
         : storage{std::move(other.storage)},
           ctx{&area},
           node{(other.node.resolve != nullptr) ? std::exchange(other.node, internal::meta_type_node{}).resolve(internal::meta_context::from(*ctx)) : std::exchange(other.node, internal::meta_type_node{})},
-          vtable{std::exchange(other.vtable, &basic_vtable<void>)} {}
+          vtable{std::exchange(other.vtable, nullptr)} {}
 
     /**
      * @brief Copy constructor.
@@ -332,7 +332,7 @@ public:
         : storage{std::move(other.storage)},
           ctx{other.ctx},
           node{std::exchange(other.node, internal::meta_type_node{})},
-          vtable{std::exchange(other.vtable, &basic_vtable<void>)} {}
+          vtable{std::exchange(other.vtable, nullptr)} {}
 
     /*! @brief Frees the internal storage, whatever it means. */
     ~meta_any() {
@@ -368,7 +368,7 @@ public:
         storage = std::move(other.storage);
         ctx = other.ctx;
         node = std::exchange(other.node, internal::meta_type_node{});
-        vtable = std::exchange(other.vtable, &basic_vtable<void>);
+        vtable = std::exchange(other.vtable, nullptr);
         return *this;
     }
 
@@ -546,7 +546,7 @@ public:
         release();
         storage.reset();
         node = {};
-        vtable = &basic_vtable<void>;
+        vtable = nullptr;
     }
 
     /**
@@ -555,14 +555,14 @@ public:
      */
     [[nodiscard]] meta_sequence_container as_sequence_container() noexcept {
         meta_sequence_container proxy = (storage.policy() == any_policy::cref) ? std::as_const(*this).as_sequence_container() : meta_sequence_container{};
-        if(!proxy) { vtable(internal::meta_traits::is_sequence_container, *ctx, storage.data(), &proxy); }
+        if(!proxy && vtable) { vtable(internal::meta_traits::is_sequence_container, *ctx, storage.data(), &proxy); }
         return proxy;
     }
 
     /*! @copydoc as_sequence_container */
     [[nodiscard]] meta_sequence_container as_sequence_container() const noexcept {
         meta_sequence_container proxy{};
-        vtable(internal::meta_traits::is_sequence_container | internal::meta_traits::is_const, *ctx, storage.data(), &proxy);
+        if(vtable) { vtable(internal::meta_traits::is_sequence_container | internal::meta_traits::is_const, *ctx, storage.data(), &proxy); }
         return proxy;
     }
 
@@ -572,14 +572,14 @@ public:
      */
     [[nodiscard]] meta_associative_container as_associative_container() noexcept {
         meta_associative_container proxy = (storage.policy() == any_policy::cref) ? std::as_const(*this).as_associative_container() : meta_associative_container{};
-        if(!proxy) { vtable(internal::meta_traits::is_associative_container, *ctx, storage.data(), &proxy); }
+        if(!proxy && vtable) { vtable(internal::meta_traits::is_associative_container, *ctx, storage.data(), &proxy); }
         return proxy;
     }
 
     /*! @copydoc as_associative_container */
     [[nodiscard]] meta_associative_container as_associative_container() const noexcept {
         meta_associative_container proxy{};
-        vtable(internal::meta_traits::is_associative_container | internal::meta_traits::is_const, *ctx, storage.data(), &proxy);
+        if(vtable) { vtable(internal::meta_traits::is_associative_container | internal::meta_traits::is_const, *ctx, storage.data(), &proxy); }
         return proxy;
     }
 
@@ -590,7 +590,7 @@ public:
      */
     [[nodiscard]] meta_any operator*() const noexcept {
         meta_any ret{meta_ctx_arg, *ctx};
-        vtable(internal::meta_traits::is_pointer_like, *ctx, storage.data(), &ret);
+        if(vtable) { vtable(internal::meta_traits::is_pointer_like, *ctx, storage.data(), &ret); }
         return ret;
     }
 
@@ -642,7 +642,7 @@ private:
     any storage{};
     const meta_ctx *ctx{&locator<meta_ctx>::value_or()};
     internal::meta_type_node node{};
-    vtable_type *vtable{&basic_vtable<void>};
+    vtable_type *vtable{};
 };
 
 /**