Zero initialize all pointer class and struct members

This prevents the pitfall of UB when checking if they have been
assigned something valid by comparing to nullptr.

28 files changed, 67 insertions, 90 deletions

diff --git a/core/config/engine.h b/core/config/engine.h
index 1adab9b96f..eac96852b3 100644
--- a/core/config/engine.h
+++ b/core/config/engine.h
@@ -40,7 +40,7 @@ class Engine {
 public:
 	struct Singleton {
 		StringName name;
-		Object *ptr;
+		Object *ptr = nullptr;
 		StringName class_name; //used for binding generation hinting
 		bool user_created = false;
 		Singleton(const StringName &p_name = StringName(), Object *p_ptr = nullptr, const StringName &p_class_name = StringName());
diff --git a/core/core_bind.h b/core/core_bind.h
index 907f37c5fa..4d26698f99 100644
--- a/core/core_bind.h
+++ b/core/core_bind.h
@@ -447,7 +447,7 @@ public:
 
 class Directory : public RefCounted {
 	GDCLASS(Directory, RefCounted);
-	DirAccess *d;
+	DirAccess *d = nullptr;
 
 	bool dir_open = false;
 	bool include_navigational = false;
diff --git a/core/io/file_access.h b/core/io/file_access.h
index a6cb5d9fc6..a5150010da 100644
--- a/core/io/file_access.h
+++ b/core/io/file_access.h
@@ -183,7 +183,7 @@ struct FileAccessRef {
 
 	operator bool() const { return f != nullptr; }
 
-	FileAccess *f;
+	FileAccess *f = nullptr;
 
 	operator FileAccess *() { return f; }
 
diff --git a/core/io/file_access_pack.h b/core/io/file_access_pack.h
index 6eee2f593d..fe4b12aef6 100644
--- a/core/io/file_access_pack.h
+++ b/core/io/file_access_pack.h
@@ -64,7 +64,7 @@ public:
 		uint64_t offset; //if offset is ZERO, the file was ERASED
 		uint64_t size;
 		uint8_t md5[16];
-		PackSource *src;
+		PackSource *src = nullptr;
 		bool encrypted;
 	};
 
@@ -103,7 +103,7 @@ private:
 
 	Vector<PackSource *> sources;
 
-	PackedDir *root;
+	PackedDir *root = nullptr;
 
 	static PackedData *singleton;
 	bool disabled = false;
@@ -150,7 +150,7 @@ class FileAccessPack : public FileAccess {
 	mutable bool eof;
 	uint64_t off;
 
-	FileAccess *f;
+	FileAccess *f = nullptr;
 	virtual Error _open(const String &p_path, int p_mode_flags);
 	virtual uint64_t _get_modified_time(const String &p_file) { return 0; }
 	virtual uint32_t _get_unix_permissions(const String &p_file) { return 0; }
diff --git a/core/io/ip.h b/core/io/ip.h
index ebd944a949..06ff8a4d70 100644
--- a/core/io/ip.h
+++ b/core/io/ip.h
@@ -62,7 +62,7 @@ public:
 	typedef int ResolverID;
 
 private:
-	_IP_ResolverPrivate *resolver;
+	_IP_ResolverPrivate *resolver = nullptr;
 
 protected:
 	static IP *singleton;
diff --git a/core/io/resource_format_binary.h b/core/io/resource_format_binary.h
index c80c9b0ac9..5403168a53 100644
--- a/core/io/resource_format_binary.h
+++ b/core/io/resource_format_binary.h
@@ -127,7 +127,7 @@ class ResourceFormatSaverBinaryInstance {
 	bool skip_editor;
 	bool big_endian;
 	bool takeover_paths;
-	FileAccess *f;
+	FileAccess *f = nullptr;
 	String magic;
 	Set<RES> resource_set;
 
diff --git a/core/io/resource_uid.h b/core/io/resource_uid.h
index 1ea44b9d06..0b7ffdf6d0 100644
--- a/core/io/resource_uid.h
+++ b/core/io/resource_uid.h
@@ -46,7 +46,7 @@ public:
 	static String get_cache_file();
 
 private:
-	void *crypto; // CryptoCore::RandomGenerator (avoid including crypto_core.h)
+	void *crypto = nullptr; // CryptoCore::RandomGenerator (avoid including crypto_core.h)
 	Mutex mutex;
 	struct Cache {
 		CharString cs;
diff --git a/core/io/udp_server.h b/core/io/udp_server.h
index 4a7546fddf..47f06b2490 100644
--- a/core/io/udp_server.h
+++ b/core/io/udp_server.h
@@ -43,7 +43,7 @@ protected:
 	};
 
 	struct Peer {
-		PacketPeerUDP *peer;
+		PacketPeerUDP *peer = nullptr;
 		IPAddress ip;
 		uint16_t port = 0;
 
diff --git a/core/math/bvh.h b/core/math/bvh.h
index f429ce189b..9f6ab9f736 100644
--- a/core/math/bvh.h
+++ b/core/math/bvh.h
@@ -763,19 +763,19 @@ private:
 		tree._extra[p_handle.id()].last_updated_tick = 0;
 	}
 
-	PairCallback pair_callback;
-	UnpairCallback unpair_callback;
-	CheckPairCallback check_pair_callback;
-	void *pair_callback_userdata;
-	void *unpair_callback_userdata;
-	void *check_pair_callback_userdata;
+	PairCallback pair_callback = nullptr;
+	UnpairCallback unpair_callback = nullptr;
+	CheckPairCallback check_pair_callback = nullptr;
+	void *pair_callback_userdata = nullptr;
+	void *unpair_callback_userdata = nullptr;
+	void *check_pair_callback_userdata = nullptr;
 
 	BVHTREE_CLASS tree;
 
 	// for collision pairing,
 	// maintain a list of all items moved etc on each frame / tick
 	LocalVector<BVHHandle, uint32_t, true> changed_items;
-	uint32_t _tick;
+	uint32_t _tick = 1; // Start from 1 so items with 0 indicate never updated.
 
 	class BVHLockedFunction {
 	public:
@@ -801,23 +801,16 @@ private:
 		}
 
 	private:
-		Mutex *_mutex;
+		Mutex *_mutex = nullptr;
 	};
 
 	Mutex _mutex;
 
 	// local toggle for turning on and off thread safety in project settings
-	bool _thread_safe;
+	bool _thread_safe = BVH_THREAD_SAFE;
 
 public:
-	BVH_Manager() {
-		_tick = 1; // start from 1 so items with 0 indicate never updated
-		pair_callback = nullptr;
-		unpair_callback = nullptr;
-		pair_callback_userdata = nullptr;
-		unpair_callback_userdata = nullptr;
-		_thread_safe = BVH_THREAD_SAFE;
-	}
+	BVH_Manager() {}
 };
 
 #undef BVHTREE_CLASS
diff --git a/core/math/dynamic_bvh.h b/core/math/dynamic_bvh.h
index 50ec2c2b30..74831089f3 100644
--- a/core/math/dynamic_bvh.h
+++ b/core/math/dynamic_bvh.h
@@ -183,7 +183,7 @@ private:
 		Node *parent = nullptr;
 		union {
 			Node *childs[2];
-			void *data;
+			void *data = nullptr;
 		};
 
 		_FORCE_INLINE_ bool is_leaf() const { return childs[1] == nullptr; }
@@ -215,10 +215,7 @@ private:
 			return axis.dot(volume.get_center() - org) <= 0;
 		}
 
-		Node() {
-			childs[0] = nullptr;
-			childs[1] = nullptr;
-		}
+		Node() {}
 	};
 
 	PagedAllocator<Node> node_allocator;
diff --git a/core/math/expression.h b/core/math/expression.h
index 9b87bdd6ec..d43cc4091a 100644
--- a/core/math/expression.h
+++ b/core/math/expression.h
@@ -147,7 +147,7 @@ private:
 		bool is_op = false;
 		union {
 			Variant::Operator op;
-			ENode *node;
+			ENode *node = nullptr;
 		};
 	};
 
diff --git a/core/math/octree.h b/core/math/octree.h
index e73f8213b3..65ab9e2292 100644
--- a/core/math/octree.h
+++ b/core/math/octree.h
@@ -134,7 +134,7 @@ private:
 		List<PairData *, AL> pair_list;
 
 		struct OctantOwner {
-			Octant *octant;
+			Octant *octant = nullptr;
 			typename List<Element *, AL>::Element *E;
 		}; // an element can be in max 8 octants
 
@@ -147,7 +147,7 @@ private:
 		int refcount;
 		bool intersect;
 		Element *A, *B;
-		void *ud;
+		void *ud = nullptr;
 		typename List<PairData *, AL>::Element *eA, *eB;
 	};
 
@@ -156,18 +156,18 @@ private:
 	ElementMap element_map;
 	PairMap pair_map;
 
-	PairCallback pair_callback;
-	UnpairCallback unpair_callback;
-	void *pair_callback_userdata;
-	void *unpair_callback_userdata;
+	PairCallback pair_callback = nullptr;
+	UnpairCallback unpair_callback = nullptr;
+	void *pair_callback_userdata = nullptr;
+	void *unpair_callback_userdata = nullptr;
 
-	OctreeElementID last_element_id;
-	uint64_t pass;
+	OctreeElementID last_element_id = 1;
+	uint64_t pass = 1;
 
-	real_t unit_size;
-	Octant *root;
-	int octant_count;
-	int pair_count;
+	real_t unit_size = 1.0;
+	Octant *root = nullptr;
+	int octant_count = 0;
+	int pair_count = 0;
 
 	_FORCE_INLINE_ void _pair_check(PairData *p_pair) {
 		bool intersect = p_pair->A->aabb.intersects_inclusive(p_pair->B->aabb);
@@ -294,7 +294,7 @@ private:
 		const Vector3 *points;
 		int point_count;
 		T **result_array;
-		int *result_idx;
+		int *result_idx = nullptr;
 		int result_max;
 		uint32_t mask;
 	};
@@ -1265,18 +1265,7 @@ void Octree<T, use_pairs, AL>::set_unpair_callback(UnpairCallback p_callback, vo
 
 template <class T, bool use_pairs, class AL>
 Octree<T, use_pairs, AL>::Octree(real_t p_unit_size) {
-	last_element_id = 1;
-	pass = 1;
 	unit_size = p_unit_size;
-	root = nullptr;
-
-	octant_count = 0;
-	pair_count = 0;
-
-	pair_callback = nullptr;
-	unpair_callback = nullptr;
-	pair_callback_userdata = nullptr;
-	unpair_callback_userdata = nullptr;
 }
 
 #endif // OCTREE_H
diff --git a/core/object/callable_method_pointer.h b/core/object/callable_method_pointer.h
index 3cd9ad3819..577d4b9fbd 100644
--- a/core/object/callable_method_pointer.h
+++ b/core/object/callable_method_pointer.h
@@ -38,7 +38,7 @@
 #include "core/variant/callable.h"
 
 class CallableCustomMethodPointerBase : public CallableCustom {
-	uint32_t *comp_ptr;
+	uint32_t *comp_ptr = nullptr;
 	uint32_t comp_size;
 	uint32_t h;
 #ifdef DEBUG_METHODS_ENABLED
diff --git a/core/object/class_db.h b/core/object/class_db.h
index b8a4b3ea2b..5da8523743 100644
--- a/core/object/class_db.h
+++ b/core/object/class_db.h
@@ -85,8 +85,8 @@ public:
 		int index;
 		StringName setter;
 		StringName getter;
-		MethodBind *_setptr;
-		MethodBind *_getptr;
+		MethodBind *_setptr = nullptr;
+		MethodBind *_getptr = nullptr;
 		Variant::Type type;
 	};
 
diff --git a/core/object/message_queue.h b/core/object/message_queue.h
index eaab01d0aa..2219cdb8f6 100644
--- a/core/object/message_queue.h
+++ b/core/object/message_queue.h
@@ -62,10 +62,10 @@ class MessageQueue {
 		};
 	};
 
-	uint8_t *buffer;
+	uint8_t *buffer = nullptr;
 	uint32_t buffer_end = 0;
 	uint32_t buffer_max_used = 0;
-	uint32_t buffer_size;
+	uint32_t buffer_size = 0;
 
 	void _call_function(const Callable &p_callable, const Variant *p_args, int p_argcount, bool p_show_error);
 
diff --git a/core/object/object.h b/core/object/object.h
index b640c4e78a..eeef03dcb9 100644
--- a/core/object/object.h
+++ b/core/object/object.h
@@ -538,8 +538,8 @@ private:
 
 	std::mutex _instance_binding_mutex;
 	struct InstanceBinding {
-		void *binding;
-		void *token;
+		void *binding = nullptr;
+		void *token = nullptr;
 		GDNativeInstanceBindingFreeCallback free_callback = nullptr;
 		GDNativeInstanceBindingReferenceCallback reference_callback = nullptr;
 	};
@@ -849,7 +849,7 @@ class ObjectDB {
 		uint64_t validator : OBJECTDB_VALIDATOR_BITS;
 		uint64_t next_free : OBJECTDB_SLOT_MAX_COUNT_BITS;
 		uint64_t is_ref_counted : 1;
-		Object *object;
+		Object *object = nullptr;
 	};
 
 	static SpinLock spin_lock;
diff --git a/core/object/script_language.h b/core/object/script_language.h
index af4f276825..08b82d798e 100644
--- a/core/object/script_language.h
+++ b/core/object/script_language.h
@@ -430,11 +430,11 @@ public:
 extern uint8_t script_encryption_key[32];
 
 class PlaceHolderScriptInstance : public ScriptInstance {
-	Object *owner;
+	Object *owner = nullptr;
 	List<PropertyInfo> properties;
 	Map<StringName, Variant> values;
 	Map<StringName, Variant> constants;
-	ScriptLanguage *language;
+	ScriptLanguage *language = nullptr;
 	Ref<Script> script;
 
 public:
diff --git a/core/os/memory.h b/core/os/memory.h
index 27eaad5010..baa96ef3e9 100644
--- a/core/os/memory.h
+++ b/core/os/memory.h
@@ -186,9 +186,9 @@ void memdelete_arr(T *p_class) {
 
 struct _GlobalNil {
 	int color = 1;
-	_GlobalNil *right;
-	_GlobalNil *left;
-	_GlobalNil *parent;
+	_GlobalNil *right = nullptr;
+	_GlobalNil *left = nullptr;
+	_GlobalNil *parent = nullptr;
 
 	_GlobalNil();
 };
diff --git a/core/os/os.h b/core/os/os.h
index 808d704b3d..b3c66ff18c 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -60,8 +60,6 @@ class OS {
 	bool _stdout_enabled = true;
 	bool _stderr_enabled = true;
 
-	char *last_error;
-
 	CompositeLogger *_logger = nullptr;
 
 	bool restart_on_exit = false;
diff --git a/core/os/pool_allocator.h b/core/os/pool_allocator.h
index 11a252bc54..0919a024e2 100644
--- a/core/os/pool_allocator.h
+++ b/core/os/pool_allocator.h
@@ -75,13 +75,13 @@ private:
 	typedef int EntryArrayPos;
 	typedef int EntryIndicesPos;
 
-	Entry *entry_array;
-	int *entry_indices;
+	Entry *entry_array = nullptr;
+	int *entry_indices = nullptr;
 	int entry_max;
 	int entry_count;
 
-	uint8_t *pool;
-	void *mem_ptr;
+	uint8_t *pool = nullptr;
+	void *mem_ptr = nullptr;
 	int pool_size;
 
 	int free_mem;
diff --git a/core/string/string_name.h b/core/string/string_name.h
index 6f08d32981..f4233854ac 100644
--- a/core/string/string_name.h
+++ b/core/string/string_name.h
@@ -70,7 +70,7 @@ class StringName {
 	_Data *_data = nullptr;
 
 	union _HashUnion {
-		_Data *ptr;
+		_Data *ptr = nullptr;
 		uint32_t hash;
 	};
 
diff --git a/core/templates/command_queue_mt.h b/core/templates/command_queue_mt.h
index 1ecb81c2a2..0aa1cfd541 100644
--- a/core/templates/command_queue_mt.h
+++ b/core/templates/command_queue_mt.h
@@ -311,7 +311,7 @@ class CommandQueueMT {
 	};
 
 	struct SyncCommand : public CommandBase {
-		SyncSemaphore *sync_sem;
+		SyncSemaphore *sync_sem = nullptr;
 
 		virtual void post() {
 			sync_sem->sem.post();
diff --git a/core/templates/map.h b/core/templates/map.h
index f228640a1e..c54da1dc03 100644
--- a/core/templates/map.h
+++ b/core/templates/map.h
@@ -178,7 +178,7 @@ public:
 private:
 	struct _Data {
 		Element *_root = nullptr;
-		Element *_nil;
+		Element *_nil = nullptr;
 		int size_cache = 0;
 
 		_FORCE_INLINE_ _Data() {
@@ -344,7 +344,7 @@ private:
 	void _insert_rb_fix(Element *p_new_node) {
 		Element *node = p_new_node;
 		Element *nparent = node->parent;
-		Element *ngrand_parent;
+		Element *ngrand_parent = nullptr;
 
 		while (nparent->color == RED) {
 			ngrand_parent = nparent->parent;
@@ -500,7 +500,7 @@ private:
 		Element *rp = ((p_node->left == _data._nil) || (p_node->right == _data._nil)) ? p_node : p_node->_next;
 		Element *node = (rp->left == _data._nil) ? rp->right : rp->left;
 
-		Element *sibling;
+		Element *sibling = nullptr;
 		if (rp == rp->parent->left) {
 			rp->parent->left = node;
 			sibling = rp->parent->right;
diff --git a/core/templates/oa_hash_map.h b/core/templates/oa_hash_map.h
index 4e712fccf2..e4d9323c45 100644
--- a/core/templates/oa_hash_map.h
+++ b/core/templates/oa_hash_map.h
@@ -306,7 +306,7 @@ public:
 		bool valid;
 
 		const TKey *key;
-		TValue *value;
+		TValue *value = nullptr;
 
 	private:
 		uint32_t pos;
diff --git a/core/templates/safe_list.h b/core/templates/safe_list.h
index 53fc3fe5f9..ae31525dd0 100644
--- a/core/templates/safe_list.h
+++ b/core/templates/safe_list.h
@@ -75,8 +75,8 @@ public:
 	class Iterator {
 		friend class SafeList;
 
-		SafeListNode *cursor;
-		SafeList *list;
+		SafeListNode *cursor = nullptr;
+		SafeList *list = nullptr;
 
 		Iterator(SafeListNode *p_cursor, SafeList *p_list) :
 				cursor(p_cursor), list(p_list) {
@@ -253,8 +253,8 @@ public:
 	class Iterator {
 		friend class SafeList;
 
-		SafeListNode *cursor;
-		SafeList *list;
+		SafeListNode *cursor = nullptr;
+		SafeList *list = nullptr;
 
 	public:
 		Iterator(SafeListNode *p_cursor, SafeList *p_list) :
diff --git a/core/templates/self_list.h b/core/templates/self_list.h
index 7f2236fa3a..719b5f2e63 100644
--- a/core/templates/self_list.h
+++ b/core/templates/self_list.h
@@ -108,7 +108,7 @@ public:
 
 private:
 	List *_root = nullptr;
-	T *_self;
+	T *_self = nullptr;
 	SelfList<T> *_next = nullptr;
 	SelfList<T> *_prev = nullptr;
 
diff --git a/core/templates/set.h b/core/templates/set.h
index cdc6e8447d..a8a0a77712 100644
--- a/core/templates/set.h
+++ b/core/templates/set.h
@@ -328,7 +328,7 @@ private:
 	void _insert_rb_fix(Element *p_new_node) {
 		Element *node = p_new_node;
 		Element *nparent = node->parent;
-		Element *ngrand_parent;
+		Element *ngrand_parent = nullptr;
 
 		while (nparent->color == RED) {
 			ngrand_parent = nparent->parent;
@@ -482,7 +482,7 @@ private:
 		Element *rp = ((p_node->left == _data._nil) || (p_node->right == _data._nil)) ? p_node : p_node->_next;
 		Element *node = (rp->left == _data._nil) ? rp->right : rp->left;
 
-		Element *sibling;
+		Element *sibling = nullptr;
 		if (rp == rp->parent->left) {
 			rp->parent->left = node;
 			sibling = rp->parent->right;
diff --git a/core/templates/thread_work_pool.h b/core/templates/thread_work_pool.h
index 957af44f48..d364ac4fd8 100644
--- a/core/templates/thread_work_pool.h
+++ b/core/templates/thread_work_pool.h
@@ -68,7 +68,7 @@ class ThreadWorkPool {
 		Semaphore start;
 		Semaphore completed;
 		std::atomic<bool> exit;
-		BaseWork *work;
+		BaseWork *work = nullptr;
 	};
 
 	ThreadData *threads = nullptr;