fix #279805: Changing instrument in the mixer crashes the application

I don't know how it could work before.
Keep MidiPatches list in the Zerberus class to be aligned with Fluid architecture. Sync load/delete soundfonts with patches list updates. Now, it should work as it is done in Fluid.

Most probably I fixed a memory leak related to static QList of MidiPatch pointers created on demand and updated each call which led to dead pointers here and there and not clearing memory.

mscore/mixerdetails.cpp

@@ -170,7 +170,7 @@ void MixerDetails::updateFromTrack()
       //Populate patch combo
       patchCombo->blockSignals(true);
       patchCombo->clear();
-      const QList<MidiPatch*> pl = synti->getPatchInfo();
+      const auto& pl = synti->getPatchInfo();
       int patchIndex = 0;
 
       for (const MidiPatch* p : pl) {

mscore/parteditbase.cpp

@@ -341,7 +341,7 @@ void PartEdit::drumsetToggled(bool val, bool syncControls)
 
       part->undoChangeProperty(Pid::USE_DRUMSET, val);
       patch->clear();
-      const QList<MidiPatch*> pl = synti->getPatchInfo();
+      const auto& pl = synti->getPatchInfo();
       for (const MidiPatch* p : pl) {
             if (p->drum == val)
                   patch->addItem(p->name, QVariant::fromValue<void*>((void*)p));

zerberus/zerberus.cpp

@@ -76,6 +76,8 @@ Zerberus::~Zerberus()
             }
       for (Channel* c : _channel)
             delete c;
+
+      qDeleteAll(patches);
       }
 
 //---------------------------------------------------------
@@ -249,18 +251,16 @@ const char* Zerberus::name() const
 //   getPatchInfo
 //---------------------------------------------------------
 
-const QList<Ms::MidiPatch*>& Zerberus::getPatchInfo() const
+void Zerberus::updatePatchList()
       {
-      static QList<Ms::MidiPatch*> pl;
-      qDeleteAll(pl);
-      pl.clear();
+      qDeleteAll(patches);
+      patches.clear();
       int idx = 0;
       for (ZInstrument* i : instruments) {
             Ms::MidiPatch* p = new Ms::MidiPatch { false, name(), 0, idx, i->name() };
-            pl.append(p);
+            patches.append(p);
             ++idx;
             }
-      return pl;
       }
 
 //---------------------------------------------------------
@@ -296,6 +296,7 @@ bool Zerberus::loadSoundFonts(const QStringList& sl)
             if (!loadInstrument(s))
                   return false;
             }
+      updatePatchList();
       return true;
       }
 
@@ -309,6 +310,7 @@ bool Zerberus::removeSoundFonts(const QStringList& fileNames)
             if (!removeSoundFont(QFileInfo(fileName).absoluteFilePath()))
                   return false;
             }
+      updatePatchList();
       return true;
       }
 
@@ -331,7 +333,9 @@ QStringList Zerberus::soundFonts() const
 bool Zerberus::addSoundFont(const QString& s)
       {
       QMutexLocker locker(&mutex);
-      return loadInstrument(s);
+      bool res = loadInstrument(s);
+      updatePatchList();
+      return res;
       }
 
 //---------------------------------------------------------
@@ -364,9 +368,13 @@ bool Zerberus::removeSoundFont(const QString& s)
                         globalInstruments.erase(it1);
                         delete i;
                         }
+
+                  updatePatchList();
                   return true;
                   }
             }
+
+      updatePatchList();
       return false;
       }
 

zerberus/zerberus.h

@@ -22,6 +22,7 @@
 
 #include "synthesizer/synthesizer.h"
 #include "synthesizer/event.h"
+#include "synthesizer/midipatch.h"
 #include "voice.h"
 
 
@@ -74,7 +75,8 @@ class VoiceFifo {
 class Zerberus : public Ms::Synthesizer {
       static bool initialized;
       static std::list<ZInstrument*> globalInstruments;
-
+      QList<Ms::MidiPatch*> patches;
+
       double _masterTuning = 440.0;
       std::atomic<bool> busy;
 
@@ -117,7 +119,6 @@ class Zerberus : public Ms::Synthesizer {
       double ct2hz(double c) const { return pow(2.0, (c-6900.0) / 1200.0) * masterTuning(); }
 
       virtual const char* name() const;
-      virtual const QList<Ms::MidiPatch*>& getPatchInfo() const;
 
       virtual Ms::SynthesizerGroup state() const;
       virtual bool setState(const Ms::SynthesizerGroup&);
@@ -131,6 +132,10 @@ class Zerberus : public Ms::Synthesizer {
       virtual bool removeSoundFonts(const QStringList& fileNames);
       virtual QStringList soundFonts() const;
 
+      virtual const QList<Ms::MidiPatch*>& getPatchInfo() const override { return patches; }
+
+      void updatePatchList();
+
       virtual Ms::SynthesizerGui* gui();
       static QFileInfoList sfzFiles();
       };