Port member initialization from constructor to declaration (C++11)

Using `clang-tidy`'s `modernize-use-default-member-init` check and
manual review of the changes, and some extra manual changes that
`clang-tidy` failed to do.

Also went manually through all of `core` to find occurrences that
`clang-tidy` couldn't handle, especially all initializations done
in a constructor without using initializer lists.

5 files changed, 34 insertions, 64 deletions

diff --git a/modules/gdnative/nativescript/nativescript.h b/modules/gdnative/nativescript/nativescript.h
index 7e7598e06c..d24b247e59 100644
--- a/modules/gdnative/nativescript/nativescript.h
+++ b/modules/gdnative/nativescript/nativescript.h
@@ -43,6 +43,7 @@
 #include "scene/main/node.h"
 
 #include "modules/gdnative/gdnative.h"
+
 #include <nativescript/godot_nativescript.h>
 
 struct NativeScriptDesc {
@@ -54,6 +55,7 @@ struct NativeScriptDesc {
 		uint16_t rpc_method_id;
 		String documentation;
 	};
+
 	struct Property {
 		godot_property_set_func setter;
 		godot_property_get_func getter;
@@ -69,9 +71,9 @@ struct NativeScriptDesc {
 		String documentation;
 	};
 
-	uint16_t rpc_count;
+	uint16_t rpc_count = 0;
 	Map<StringName, Method> methods;
-	uint16_t rset_count;
+	uint16_t rset_count = 0;
 	OrderedHashMap<StringName, Property> properties;
 	Map<StringName, Signal> signals_; // QtCreator doesn't like the name signals
 	StringName base;
@@ -82,20 +84,11 @@ struct NativeScriptDesc {
 
 	String documentation;
 
-	const void *type_tag;
+	const void *type_tag = nullptr;
 
 	bool is_tool;
 
-	inline NativeScriptDesc() :
-			rpc_count(0),
-			methods(),
-			rset_count(0),
-			properties(),
-			signals_(),
-			base(),
-			base_native_type(),
-			documentation(),
-			type_tag(nullptr) {
+	inline NativeScriptDesc() {
 		zeromem(&create_func, sizeof(godot_instance_create_func));
 		zeromem(&destroy_func, sizeof(godot_instance_destroy_func));
 	}
@@ -396,14 +389,13 @@ inline NativeScriptDesc *NativeScript::get_script_desc() const {
 
 class NativeReloadNode : public Node {
 	GDCLASS(NativeReloadNode, Node);
-	bool unloaded;
+	bool unloaded = false;
 
 public:
 	static void _bind_methods();
 	void _notification(int p_what);
 
-	NativeReloadNode() :
-			unloaded(false) {}
+	NativeReloadNode() {}
 };
 
 class ResourceFormatLoaderNativeScript : public ResourceFormatLoader {
diff --git a/modules/gdnative/pluginscript/pluginscript_script.cpp b/modules/gdnative/pluginscript/pluginscript_script.cpp
index 6b303c8716..9b00d654d1 100644
--- a/modules/gdnative/pluginscript/pluginscript_script.cpp
+++ b/modules/gdnative/pluginscript/pluginscript_script.cpp
@@ -550,11 +550,6 @@ MultiplayerAPI::RPCMode PluginScript::get_rset_mode(const StringName &p_variable
 }
 
 PluginScript::PluginScript() :
-		_data(nullptr),
-		_desc(nullptr),
-		_language(nullptr),
-		_tool(false),
-		_valid(false),
 		_script_list(this) {
 }
 
diff --git a/modules/gdnative/pluginscript/pluginscript_script.h b/modules/gdnative/pluginscript/pluginscript_script.h
index 70b9ca980b..287f42bf7b 100644
--- a/modules/gdnative/pluginscript/pluginscript_script.h
+++ b/modules/gdnative/pluginscript/pluginscript_script.h
@@ -45,11 +45,11 @@ class PluginScript : public Script {
 	friend class PluginScriptLanguage;
 
 private:
-	godot_pluginscript_script_data *_data;
-	const godot_pluginscript_script_desc *_desc;
-	PluginScriptLanguage *_language;
-	bool _tool;
-	bool _valid;
+	godot_pluginscript_script_data *_data = nullptr;
+	const godot_pluginscript_script_desc *_desc = nullptr;
+	PluginScriptLanguage *_language = nullptr;
+	bool _tool = false;
+	bool _valid = false;
 
 	Ref<Script> _ref_base_parent;
 	StringName _native_parent;
diff --git a/modules/gdnative/videodecoder/video_stream_gdnative.cpp b/modules/gdnative/videodecoder/video_stream_gdnative.cpp
index f7d87595af..a2ff376e31 100644
--- a/modules/gdnative/videodecoder/video_stream_gdnative.cpp
+++ b/modules/gdnative/videodecoder/video_stream_gdnative.cpp
@@ -202,22 +202,7 @@ void VideoStreamPlaybackGDNative::update_texture() {
 // ctor and dtor
 
 VideoStreamPlaybackGDNative::VideoStreamPlaybackGDNative() :
-		texture(Ref<ImageTexture>(memnew(ImageTexture))),
-		playing(false),
-		paused(false),
-		mix_udata(nullptr),
-		mix_callback(nullptr),
-		num_channels(-1),
-		time(0),
-		seek_backward(false),
-		mix_rate(0),
-		delay_compensation(0),
-		pcm(nullptr),
-		pcm_write_idx(0),
-		samples_decoded(0),
-		file(nullptr),
-		interface(nullptr),
-		data_struct(nullptr) {}
+		texture(Ref<ImageTexture>(memnew(ImageTexture))) {}
 
 VideoStreamPlaybackGDNative::~VideoStreamPlaybackGDNative() {
 	cleanup();
diff --git a/modules/gdnative/videodecoder/video_stream_gdnative.h b/modules/gdnative/videodecoder/video_stream_gdnative.h
index 092e10a0f5..f1bae22801 100644
--- a/modules/gdnative/videodecoder/video_stream_gdnative.h
+++ b/modules/gdnative/videodecoder/video_stream_gdnative.h
@@ -37,13 +37,11 @@
 #include "scene/resources/video_stream.h"
 
 struct VideoDecoderGDNative {
-	const godot_videodecoder_interface_gdnative *interface;
-	String plugin_name;
+	const godot_videodecoder_interface_gdnative *interface = nullptr;
+	String plugin_name = "none";
 	Vector<String> supported_extensions;
 
-	VideoDecoderGDNative() :
-			interface(nullptr),
-			plugin_name("none") {}
+	VideoDecoderGDNative() {}
 
 	VideoDecoderGDNative(const godot_videodecoder_interface_gdnative *p_interface) :
 			interface(p_interface),
@@ -111,23 +109,23 @@ class VideoStreamPlaybackGDNative : public VideoStreamPlayback {
 	GDCLASS(VideoStreamPlaybackGDNative, VideoStreamPlayback);
 
 	Ref<ImageTexture> texture;
-	bool playing;
-	bool paused;
+	bool playing = false;
+	bool paused = false;
 
 	Vector2 texture_size;
 
-	void *mix_udata;
-	AudioMixCallback mix_callback;
+	void *mix_udata = nullptr;
+	AudioMixCallback mix_callback = nullptr;
 
-	int num_channels;
-	float time;
-	bool seek_backward;
-	int mix_rate;
-	double delay_compensation;
+	int num_channels = -1;
+	float time = 0;
+	bool seek_backward = false;
+	int mix_rate = 0;
+	double delay_compensation = 0;
 
-	float *pcm;
-	int pcm_write_idx;
-	int samples_decoded;
+	float *pcm = nullptr;
+	int pcm_write_idx = 0;
+	int samples_decoded = 0;
 
 	void cleanup();
 	void update_texture();
@@ -135,10 +133,10 @@ class VideoStreamPlaybackGDNative : public VideoStreamPlayback {
 protected:
 	String file_name;
 
-	FileAccess *file;
+	FileAccess *file = nullptr;
 
-	const godot_videodecoder_interface_gdnative *interface;
-	void *data_struct;
+	const godot_videodecoder_interface_gdnative *interface = nullptr;
+	void *data_struct = nullptr;
 
 public:
 	VideoStreamPlaybackGDNative();
@@ -181,7 +179,7 @@ class VideoStreamGDNative : public VideoStream {
 	GDCLASS(VideoStreamGDNative, VideoStream);
 
 	String file;
-	int audio_track;
+	int audio_track = 0;
 
 protected:
 	static void
@@ -194,7 +192,7 @@ public:
 	virtual void set_audio_track(int p_track);
 	virtual Ref<VideoStreamPlayback> instance_playback();
 
-	VideoStreamGDNative() { audio_track = 0; }
+	VideoStreamGDNative() {}
 };
 
 class ResourceFormatLoaderVideoStreamGDNative : public ResourceFormatLoader {