Core: Expand is_zero_constructible coverage

core/io/ip_address.h

@@ -94,3 +94,7 @@ public:
 	IPAddress(uint32_t p_a, uint32_t p_b, uint32_t p_c, uint32_t p_d, bool is_v6 = false);
 	IPAddress() { clear(); }
 };
+
+// Zero-constructing IPAddress initializes field, valid, and wildcard to 0 (and thus empty).
+template <>
+struct is_zero_constructible<IPAddress> : std::true_type {};

core/object/object_id.h

@@ -58,3 +58,6 @@ public:
 	_ALWAYS_INLINE_ explicit ObjectID(const uint64_t p_id) { id = p_id; }
 	_ALWAYS_INLINE_ explicit ObjectID(const int64_t p_id) { id = p_id; }
 };
+
+template <>
+struct is_zero_constructible<ObjectID> : std::true_type {};

core/object/ref_counted.h

@@ -276,3 +276,7 @@ struct VariantInternalAccessor<const Ref<T> &> {
 	static _FORCE_INLINE_ Ref<T> get(const Variant *v) { return Ref<T>(*VariantInternal::get_object(v)); }
 	static _FORCE_INLINE_ void set(Variant *v, const Ref<T> &p_ref) { VariantInternal::object_assign(v, p_ref); }
 };
+
+// Zero-constructing Ref initializes reference to nullptr (and thus empty).
+template <typename T>
+struct is_zero_constructible<Ref<T>> : std::true_type {};

core/string/node_path.h

@@ -95,3 +95,7 @@ public:
 	NodePath() {}
 	~NodePath();
 };
+
+// Zero-constructing NodePath initializes data to nullptr (and thus empty).
+template <>
+struct is_zero_constructible<NodePath> : std::true_type {};

core/string/string_name.h

@@ -219,6 +219,10 @@ public:
 #endif
 };
 
+// Zero-constructing StringName initializes _data to nullptr (and thus empty).
+template <>
+struct is_zero_constructible<StringName> : std::true_type {};
+
 bool operator==(const String &p_name, const StringName &p_string_name);
 bool operator!=(const String &p_name, const StringName &p_string_name);
 bool operator==(const char *p_name, const StringName &p_string_name);

core/templates/pair.h

@@ -77,6 +77,10 @@ struct PairHash {
 	}
 };
 
+// Pair is zero-constructible if and only if both constrained types are zero-constructible.
+template <typename F, typename S>
+struct is_zero_constructible<Pair<F, S>> : std::conjunction<is_zero_constructible<F>, is_zero_constructible<S>> {};
+
 template <typename K, typename V>
 struct KeyValue {
 	const K key;
@@ -109,3 +113,7 @@ struct KeyValueSort {
 		return A.key < B.key;
 	}
 };
+
+// KeyValue is zero-constructible if and only if both constrained types are zero-constructible.
+template <typename K, typename V>
+struct is_zero_constructible<KeyValue<K, V>> : std::conjunction<is_zero_constructible<K>, is_zero_constructible<V>> {};

core/templates/rid.h

@@ -71,3 +71,6 @@ public:
 
 	_ALWAYS_INLINE_ RID() {}
 };
+
+template <>
+struct is_zero_constructible<RID> : std::true_type {};

core/templates/span.h

@@ -113,3 +113,7 @@ constexpr uint64_t Span<T>::count(const T &p_val) const {
 	}
 	return amount;
 }
+
+// Zero-constructing Span initializes _ptr and _len to 0 (and thus empty).
+template <typename T>
+struct is_zero_constructible<Span<T>> : std::true_type {};

core/templates/tuple.h

@@ -85,6 +85,10 @@ struct Tuple<T, Rest...> : Tuple<Rest...> {
 			value(std::forward<F>(f)) {}
 };
 
+// Tuple is zero-constructible if and only if all constrained types are zero-constructible.
+template <typename... Types>
+struct is_zero_constructible<Tuple<Types...>> : std::conjunction<is_zero_constructible<Types>...> {};
+
 template <size_t I, typename Tuple>
 struct TupleGet;
 

core/variant/callable.h

@@ -135,6 +135,10 @@ public:
 	~Callable();
 };
 
+// Zero-constructing Callable initializes method and object to 0 (and thus empty).
+template <>
+struct is_zero_constructible<Callable> : std::true_type {};
+
 class CallableCustom {
 	friend class Callable;
 	SafeRefCount ref_count;
@@ -200,6 +204,10 @@ public:
 	Signal() {}
 };
 
+// Zero-constructing Signal initializes name and object to 0 (and thus empty).
+template <>
+struct is_zero_constructible<Signal> : std::true_type {};
+
 struct CallableComparator {
 	const Callable &func;
 

core/variant/type_info.h

@@ -268,6 +268,9 @@ public:
 	_FORCE_INLINE_ BitField<T> operator^(const BitField<T> &p_b) const { return BitField<T>(value ^ p_b.value); }
 };
 
+template <typename T>
+struct is_zero_constructible<BitField<T>> : std::true_type {};
+
 #define TEMPL_MAKE_BITFIELD_TYPE_INFO(m_enum, m_impl)                                                                                            \
 	template <>                                                                                                                                  \
 	struct GetTypeInfo<m_impl> {                                                                                                                 \