fix missing virtual destructors as reported in #1386

core/src/dsp/block.h

@@ -9,6 +9,7 @@
 namespace dsp {
     class generic_block {
     public:
+        virtual ~generic_block() {}
         virtual void start() {}
         virtual void stop() {}
         virtual int run() { return -1; }
@@ -16,8 +17,6 @@ namespace dsp {
 
     class block : public generic_block {
     public:
-        virtual void init() {}
-
         virtual ~block() {
             if (!_block_init) { return; }
             stop();

core/src/dsp/operator.h

@@ -10,6 +10,8 @@ namespace dsp {
 
         Operator(stream<A>* a, stream<B>* b) { init(a, b); }
 
+        virtual ~Operator() {}
+
         virtual void init(stream<A>* a, stream<B>* b) {
             _a = a;
             _b = b;

core/src/dsp/stream.h

@@ -11,6 +11,7 @@
 namespace dsp {
     class untyped_stream {
     public:
+        virtual ~untyped_stream() {}
         virtual bool swap(int size) { return false; }
         virtual int read() { return -1; }
         virtual void flush() {}

core/src/module.h

@@ -42,6 +42,7 @@ public:
 
     class Instance {
     public:
+        virtual ~Instance() {}
         virtual void postInit() = 0;
         virtual void enable() = 0;
         virtual void disable() = 0;