Remove sources from the mixer before deleting them

src/SoundMixer/ChannelImpl.cpp

@@ -31,7 +31,7 @@ ChannelImpl::ChannelImpl(SndChannelPtr _macChannel, bool transferMacChannelOwner
 
 ChannelImpl::~ChannelImpl()
 {
-	Unlink();
+	Unlink();  // Unlink chan from list of managed chans
 
 	macChannel->channelImpl = nullptr;
 
@@ -39,6 +39,11 @@ ChannelImpl::~ChannelImpl()
 	{
 		delete macChannel;
 	}
+
+	// Make sure we've stopped mixing the source before we allow its destructor
+	// to be called. Otherwise, the WavSource's buffer may be freed as it is still
+	// being processed!
+	source.RemoveFromMixer();
 }
 
 void ChannelImpl::Recycle()

src/SoundMixer/cmixer.cpp

@@ -255,16 +255,29 @@ void Source::Init(int theSampleRate, int theLength)
 	Stop();
 }
 
-Source::~Source()
+void Source::RemoveFromMixer()
 {
 	gMixer.Lock();
 	if (active)
 	{
 		gMixer.sources.remove(this);
+		active = false;
 	}
 	gMixer.Unlock();
 }
 
+Source::~Source()
+{
+	if (active)
+	{
+		// You MUST call RemoveFromMixer before destroying a source. If you get here, your program is incorrect.
+		fprintf(stderr, "Source wasn't removed from mixer prior to destruction!\n");
+#if _DEBUG
+		std::terminate();
+#endif
+	}
+}
+
 void Source::Rewind()
 {
 	RewindImplementation();

src/SoundMixer/cmixer.h

@@ -77,6 +77,8 @@ namespace cmixer
 	public:
 		virtual ~Source();
 
+		void RemoveFromMixer();
+
 		void Clear();
 
 		void Rewind();