Don't use initializer lists for members

src/audio/mixer.cpp

@@ -437,10 +437,6 @@ void Channel::SetGroup(int group)
 }
 
 Mixer::Mixer()
-	: deviceid(0)
-	, format({ 0 })
-	, effectbuffer(0)
-	, volume(1)
 {
 	for (size_t i = 0; i < Util::CountOf(css1sources); i++) {
 		css1sources[i] = 0;

src/audio/mixer.h

@@ -178,12 +178,12 @@ private:
 	void EffectFadeU8(uint8* data, int length, int startvolume, int endvolume);
 	bool MustConvert(Source& source);
 	bool Convert(SDL_AudioCVT& cvt, const uint8* data, unsigned long length, uint8** dataout);
-	SDL_AudioDeviceID deviceid;
-	AudioFormat format;
-	uint8* effectbuffer;
+	SDL_AudioDeviceID deviceid = 0;
+	AudioFormat format = { 0 };
+	uint8* effectbuffer = nullptr;
 	std::list<Channel*> channels;
 	Source_Null source_null;
-	float volume;
+	float volume = 1.0f;
 };
 
 extern "C"

src/core/StringBuilder.hpp

@@ -29,14 +29,8 @@
 class StringBuilder final
 {
 public:
-    StringBuilder()
-    {
-        _buffer = nullptr;
-        _capacity = 0;
-        _length = 0;
-    }
-
-    explicit StringBuilder(size_t capacity) : StringBuilder()
+    StringBuilder() = default;
+    explicit StringBuilder(size_t capacity)
     {
         EnsureCapacity(capacity);
     }
@@ -170,9 +164,9 @@ public:
     size_t GetLength() const { return _length; }
 
 private:
-    utf8 * _buffer;
-    size_t _capacity;
-    size_t _length;
+    utf8 * _buffer = nullptr;
+    size_t _capacity = 0;
+    size_t _length = 0;
 
     void EnsureCapacity(size_t capacity)
     {