Style: Partially apply clang-tidy's `cppcoreguidelines-pro-type-member-init`

Didn't commit all the changes where it wants to initialize a struct
with `{}`. Should be reviewed in a separate PR.

Option `IgnoreArrays` enabled for now to be conservative, can be
disabled to see if it proposes more useful changes.

Also fixed manually a handful of other missing initializations / moved
some from constructors.

16 files changed, 65 insertions, 66 deletions

diff --git a/core/config/project_settings.cpp b/core/config/project_settings.cpp
index 06bfc0c562..79fa6a0895 100644
--- a/core/config/project_settings.cpp
+++ b/core/config/project_settings.cpp
@@ -321,9 +321,9 @@ bool ProjectSettings::_get(const StringName &p_name, Variant &r_ret) const {
 
 struct _VCSort {
 	String name;
-	Variant::Type type;
-	int order;
-	uint32_t flags;
+	Variant::Type type = Variant::VARIANT_MAX;
+	int order = 0;
+	uint32_t flags = 0;
 
 	bool operator<(const _VCSort &p_vcs) const { return order == p_vcs.order ? name < p_vcs.name : order < p_vcs.order; }
 };
diff --git a/core/core_constants.cpp b/core/core_constants.cpp
index 98b720ab65..2a514b68d8 100644
--- a/core/core_constants.cpp
+++ b/core/core_constants.cpp
@@ -41,7 +41,7 @@ struct _CoreConstant {
 	StringName enum_name;
 	bool ignore_value_in_docs = false;
 #endif
-	const char *name;
+	const char *name = nullptr;
 	int value = 0;
 
 	_CoreConstant() {}
diff --git a/core/input/input.h b/core/input/input.h
index 42016f2417..23c7ebee02 100644
--- a/core/input/input.h
+++ b/core/input/input.h
@@ -113,10 +113,10 @@ private:
 	int mouse_from_touch_index = -1;
 
 	struct VelocityTrack {
-		uint64_t last_tick;
+		uint64_t last_tick = 0;
 		Vector2 velocity;
 		Vector2 accum;
-		float accum_t;
+		float accum_t = 0.0f;
 		float min_ref_frame;
 		float max_ref_frame;
 
diff --git a/core/io/file_access_network.h b/core/io/file_access_network.h
index 6afbf6adf5..214d391c95 100644
--- a/core/io/file_access_network.h
+++ b/core/io/file_access_network.h
@@ -86,15 +86,15 @@ class FileAccessNetwork : public FileAccess {
 	Semaphore page_sem;
 	Mutex buffer_mutex;
 	bool opened = false;
-	uint64_t total_size;
+	uint64_t total_size = 0;
 	mutable uint64_t pos = 0;
-	int32_t id;
+	int32_t id = -1;
 	mutable bool eof_flag = false;
 	mutable int32_t last_page = -1;
 	mutable uint8_t *last_page_buff = nullptr;
 
-	int32_t page_size;
-	int32_t read_ahead;
+	int32_t page_size = 0;
+	int32_t read_ahead = 0;
 
 	mutable int waiting_on_page = -1;
 
@@ -108,7 +108,8 @@ class FileAccessNetwork : public FileAccess {
 
 	mutable Error response;
 
-	uint64_t exists_modtime;
+	uint64_t exists_modtime = 0;
+
 	friend class FileAccessNetworkClient;
 	void _queue_page(int32_t p_page) const;
 	void _respond(uint64_t p_len, Error p_status);
diff --git a/core/io/file_access_zip.h b/core/io/file_access_zip.h
index 2504aeedc4..ae58d99a66 100644
--- a/core/io/file_access_zip.h
+++ b/core/io/file_access_zip.h
@@ -80,7 +80,7 @@ class FileAccessZip : public FileAccess {
 	unzFile zfile = nullptr;
 	unz_file_info64 file_info;
 
-	mutable bool at_eof;
+	mutable bool at_eof = false;
 
 	void _close();
 
diff --git a/core/io/ip.cpp b/core/io/ip.cpp
index 52674150bb..5156a5cb99 100644
--- a/core/io/ip.cpp
+++ b/core/io/ip.cpp
@@ -74,8 +74,7 @@ struct _IP_ResolverPrivate {
 	Semaphore sem;
 
 	Thread thread;
-	//Semaphore* semaphore;
-	bool thread_abort;
+	bool thread_abort = false;
 
 	void resolve_queues() {
 		for (int i = 0; i < IP::RESOLVER_MAX_QUERIES; i++) {
diff --git a/core/math/convex_hull.cpp b/core/math/convex_hull.cpp
index 23a0b5dd54..996f4f4d67 100644
--- a/core/math/convex_hull.cpp
+++ b/core/math/convex_hull.cpp
@@ -666,7 +666,7 @@ public:
 		face_pool.reset(true);
 	}
 
-	Vertex *vertex_list;
+	Vertex *vertex_list = nullptr;
 
 	void compute(const Vector3 *p_coords, int32_t p_count);
 
diff --git a/core/math/geometry_2d.cpp b/core/math/geometry_2d.cpp
index 46b7d99b43..31fade5a99 100644
--- a/core/math/geometry_2d.cpp
+++ b/core/math/geometry_2d.cpp
@@ -74,14 +74,14 @@ Vector<Vector<Vector2>> Geometry2D::decompose_polygon_in_convex(Vector<Point2> p
 struct _AtlasWorkRect {
 	Size2i s;
 	Point2i p;
-	int idx;
+	int idx = 0;
 	_FORCE_INLINE_ bool operator<(const _AtlasWorkRect &p_r) const { return s.width > p_r.s.width; };
 };
 
 struct _AtlasWorkRectResult {
 	Vector<_AtlasWorkRect> result;
-	int max_w;
-	int max_h;
+	int max_w = 0;
+	int max_h = 0;
 };
 
 void Geometry2D::make_atlas(const Vector<Size2i> &p_rects, Vector<Point2i> &r_result, Size2i &r_size) {
diff --git a/core/math/random_pcg.h b/core/math/random_pcg.h
index 65fcf67664..a088b30d17 100644
--- a/core/math/random_pcg.h
+++ b/core/math/random_pcg.h
@@ -61,8 +61,8 @@ static int __bsr_clz32(uint32_t x) {
 
 class RandomPCG {
 	pcg32_random_t pcg;
-	uint64_t current_seed; // The seed the current generator state started from.
-	uint64_t current_inc;
+	uint64_t current_seed = 0; // The seed the current generator state started from.
+	uint64_t current_inc = 0;
 
 public:
 	static const uint64_t DEFAULT_SEED = 12047754176567800795U;
diff --git a/core/os/os.h b/core/os/os.h
index 9ec0dd7728..0047943056 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -54,7 +54,6 @@ class OS {
 	bool _single_window = false;
 	String _local_clipboard;
 	int _exit_code = EXIT_FAILURE; // unexpected exit is marked as failure
-	int _orientation;
 	bool _allow_hidpi = false;
 	bool _allow_layered = false;
 	bool _stdout_enabled = true;
@@ -68,7 +67,7 @@ class OS {
 	// for the user interface we keep a record of the current display driver
 	// so we can retrieve the rendering drivers available
 	int _display_driver_id = -1;
-	String _current_rendering_driver_name = "";
+	String _current_rendering_driver_name;
 
 protected:
 	void _set_logger(CompositeLogger *p_logger);
diff --git a/core/os/pool_allocator.h b/core/os/pool_allocator.h
index 27a936ed78..a7a8523aa4 100644
--- a/core/os/pool_allocator.h
+++ b/core/os/pool_allocator.h
@@ -77,20 +77,20 @@ private:
 
 	Entry *entry_array = nullptr;
 	int *entry_indices = nullptr;
-	int entry_max;
-	int entry_count;
+	int entry_max = 0;
+	int entry_count = 0;
 
 	uint8_t *pool = nullptr;
 	void *mem_ptr = nullptr;
-	int pool_size;
+	int pool_size = 0;
 
-	int free_mem;
-	int free_mem_peak;
+	int free_mem = 0;
+	int free_mem_peak = 0;
 
-	unsigned int check_count;
-	int align;
+	unsigned int check_count = 0;
+	int align = 1;
 
-	bool needs_locking;
+	bool needs_locking = false;
 
 	inline int entry_end(const Entry &p_entry) const {
 		return p_entry.pos + aligned(p_entry.len);
diff --git a/core/string/optimized_translation.cpp b/core/string/optimized_translation.cpp
index 07b58f2418..93429744fc 100644
--- a/core/string/optimized_translation.cpp
+++ b/core/string/optimized_translation.cpp
@@ -37,9 +37,9 @@ extern "C" {
 }
 
 struct CompressedString {
-	int orig_len;
+	int orig_len = 0;
 	CharString compressed;
-	int offset;
+	int offset = 0;
 };
 
 void OptimizedTranslation::generate(const Ref<Translation> &p_from) {
diff --git a/core/variant/variant_call.cpp b/core/variant/variant_call.cpp
index 9dae0720d9..cc7e84203f 100644
--- a/core/variant/variant_call.cpp
+++ b/core/variant/variant_call.cpp
@@ -949,20 +949,20 @@ struct _VariantCall {
 _VariantCall::ConstantData *_VariantCall::constant_data = nullptr;
 
 struct VariantBuiltInMethodInfo {
-	void (*call)(Variant *base, const Variant **p_args, int p_argcount, Variant &r_ret, const Vector<Variant> &p_defvals, Callable::CallError &r_error);
-	Variant::ValidatedBuiltInMethod validated_call;
-	Variant::PTRBuiltInMethod ptrcall;
+	void (*call)(Variant *base, const Variant **p_args, int p_argcount, Variant &r_ret, const Vector<Variant> &p_defvals, Callable::CallError &r_error) = nullptr;
+	Variant::ValidatedBuiltInMethod validated_call = nullptr;
+	Variant::PTRBuiltInMethod ptrcall = nullptr;
 
 	Vector<Variant> default_arguments;
 	Vector<String> argument_names;
 
-	bool is_const;
-	bool is_static;
-	bool has_return_type;
-	bool is_vararg;
+	bool is_const = false;
+	bool is_static = false;
+	bool has_return_type = false;
+	bool is_vararg = false;
 	Variant::Type return_type;
-	int argument_count;
-	Variant::Type (*get_argument_type)(int p_arg);
+	int argument_count = 0;
+	Variant::Type (*get_argument_type)(int p_arg) = nullptr;
 };
 
 typedef OAHashMap<StringName, VariantBuiltInMethodInfo> BuiltinMethodMap;
diff --git a/core/variant/variant_construct.cpp b/core/variant/variant_construct.cpp
index 351f4ae253..6b12b054a0 100644
--- a/core/variant/variant_construct.cpp
+++ b/core/variant/variant_construct.cpp
@@ -31,11 +31,11 @@
 #include "variant_construct.h"
 
 struct VariantConstructData {
-	void (*construct)(Variant &r_base, const Variant **p_args, Callable::CallError &r_error);
-	Variant::ValidatedConstructor validated_construct;
-	Variant::PTRConstructor ptr_construct;
-	Variant::Type (*get_argument_type)(int);
-	int argument_count;
+	void (*construct)(Variant &r_base, const Variant **p_args, Callable::CallError &r_error) = nullptr;
+	Variant::ValidatedConstructor validated_construct = nullptr;
+	Variant::PTRConstructor ptr_construct = nullptr;
+	Variant::Type (*get_argument_type)(int) = nullptr;
+	int argument_count = 0;
 	Vector<String> arg_names;
 };
 
diff --git a/core/variant/variant_setget.cpp b/core/variant/variant_setget.cpp
index 705aa27be6..397a57f59f 100644
--- a/core/variant/variant_setget.cpp
+++ b/core/variant/variant_setget.cpp
@@ -805,16 +805,16 @@ INDEXED_SETGET_STRUCT_TYPED(PackedColorArray, Color)
 INDEXED_SETGET_STRUCT_DICT(Dictionary)
 
 struct VariantIndexedSetterGetterInfo {
-	void (*setter)(Variant *base, int64_t index, const Variant *value, bool *valid, bool *oob);
-	void (*getter)(const Variant *base, int64_t index, Variant *value, bool *oob);
+	void (*setter)(Variant *base, int64_t index, const Variant *value, bool *valid, bool *oob) = nullptr;
+	void (*getter)(const Variant *base, int64_t index, Variant *value, bool *oob) = nullptr;
 
-	Variant::ValidatedIndexedSetter validated_setter;
-	Variant::ValidatedIndexedGetter validated_getter;
+	Variant::ValidatedIndexedSetter validated_setter = nullptr;
+	Variant::ValidatedIndexedGetter validated_getter = nullptr;
 
-	Variant::PTRIndexedSetter ptr_setter;
-	Variant::PTRIndexedGetter ptr_getter;
+	Variant::PTRIndexedSetter ptr_setter = nullptr;
+	Variant::PTRIndexedGetter ptr_getter = nullptr;
 
-	uint64_t (*get_indexed_size)(const Variant *base);
+	uint64_t (*get_indexed_size)(const Variant *base) = nullptr;
 
 	Variant::Type index_type;
 
@@ -1018,13 +1018,13 @@ struct VariantKeyedSetGetObject {
 };
 
 struct VariantKeyedSetterGetterInfo {
-	Variant::ValidatedKeyedSetter validated_setter;
-	Variant::ValidatedKeyedGetter validated_getter;
-	Variant::ValidatedKeyedChecker validated_checker;
+	Variant::ValidatedKeyedSetter validated_setter = nullptr;
+	Variant::ValidatedKeyedGetter validated_getter = nullptr;
+	Variant::ValidatedKeyedChecker validated_checker = nullptr;
 
-	Variant::PTRKeyedSetter ptr_setter;
-	Variant::PTRKeyedGetter ptr_getter;
-	Variant::PTRKeyedChecker ptr_checker;
+	Variant::PTRKeyedSetter ptr_setter = nullptr;
+	Variant::PTRKeyedGetter ptr_getter = nullptr;
+	Variant::PTRKeyedChecker ptr_checker = nullptr;
 
 	bool valid = false;
 };
diff --git a/core/variant/variant_utility.cpp b/core/variant/variant_utility.cpp
index 6ed85815be..7c821ad41d 100644
--- a/core/variant/variant_utility.cpp
+++ b/core/variant/variant_utility.cpp
@@ -1110,14 +1110,14 @@ static _FORCE_INLINE_ Variant::Type get_ret_type_helper(void (*p_func)(P...)) {
 	register_utility_function<Func_##m_func>(#m_func, m_args)
 
 struct VariantUtilityFunctionInfo {
-	void (*call_utility)(Variant *r_ret, const Variant **p_args, int p_argcount, Callable::CallError &r_error);
-	Variant::ValidatedUtilityFunction validated_call_utility;
-	Variant::PTRUtilityFunction ptr_call_utility;
+	void (*call_utility)(Variant *r_ret, const Variant **p_args, int p_argcount, Callable::CallError &r_error) = nullptr;
+	Variant::ValidatedUtilityFunction validated_call_utility = nullptr;
+	Variant::PTRUtilityFunction ptr_call_utility = nullptr;
 	Vector<String> argnames;
-	bool is_vararg;
-	bool returns_value;
-	int argcount;
-	Variant::Type (*get_arg_type)(int);
+	bool is_vararg = false;
+	bool returns_value = false;
+	int argcount = 0;
+	Variant::Type (*get_arg_type)(int) = nullptr;
 	Variant::Type return_type;
 	Variant::UtilityFunctionType type;
 };