Fix instrument memory leaks

src/engraving/dom/instrchange.cpp

@@ -79,6 +79,14 @@ InstrumentChange::~InstrumentChange()
     delete m_instrument;
 }
 
+void InstrumentChange::setInstrument(Instrument* i)
+{
+    if (m_instrument != i) {
+        delete m_instrument;
+        m_instrument = i;
+    }
+}
+
 void InstrumentChange::setInstrument(const Instrument& i)
 {
     *m_instrument = i;

src/engraving/dom/instrchange.h

@@ -48,7 +48,7 @@ class InstrumentChange final : public TextBase
     InstrumentChange* clone() const override { return new InstrumentChange(*this); }
 
     Instrument* instrument() const { return m_instrument; }
-    void setInstrument(Instrument* i) { m_instrument = i; }
+    void setInstrument(Instrument* i);
     void setInstrument(Instrument&& i) { *m_instrument = i; }
     void setInstrument(const Instrument& i);
     void setupInstrument(const Instrument* instrument);

src/engraving/dom/instrument.cpp

@@ -1041,7 +1041,10 @@ Instrument* InstrumentList::instrument(int tick)
 
 void InstrumentList::setInstrument(Instrument* instr, int tick)
 {
-    if (!insert({ tick, instr }).second) {
+    auto result = insert({ tick, instr });
+    if (!result.second) {
+        // Key already exists, delete old instrument and replace
+        delete (*this)[tick];
         (*this)[tick] = instr;
     }
 }

src/engraving/dom/part.cpp

@@ -61,6 +61,18 @@ Part::Part(Score* s)
     m_preferSharpFlat = PreferSharpFlat::AUTO;
 }
 
+//---------------------------------------------------------
+//   ~Part
+//---------------------------------------------------------
+
+Part::~Part()
+{
+    // Delete all instruments owned by this Part
+    for (auto it = m_instruments.begin(); it != m_instruments.end(); ++it) {
+        delete it->second;
+    }
+}
+
 //---------------------------------------------------------
 //   initFromInstrTemplate
 //---------------------------------------------------------
@@ -349,6 +361,10 @@ void Part::setInstrument(const Instrument& i, Fraction tick)
 
 void Part::setInstruments(const InstrumentList& instruments)
 {
+    // Delete all old instruments before clearing
+    for (auto it = m_instruments.begin(); it != m_instruments.end(); ++it) {
+        delete it->second;
+    }
     m_instruments.clear();
 
     for (auto it = instruments.begin(); it != instruments.end(); ++it) {
@@ -367,6 +383,7 @@ void Part::removeInstrument(const Fraction& tick)
         LOGD("Part::removeInstrument: not found at tick %d", tick.ticks());
         return;
     }
+    delete i->second;  // Delete the instrument before erasing
     m_instruments.erase(i);
 }
 
@@ -379,6 +396,7 @@ void Part::removeNonPrimaryInstruments()
     auto it = m_instruments.begin();
     while (it != m_instruments.end()) {
         if (it->first != -1) {
+            delete it->second;  // Delete the instrument before erasing
             it = m_instruments.erase(it);
             continue;
         }

src/engraving/dom/part.h

@@ -67,6 +67,7 @@ class Part final : public EngravingObject
     static const int DEFAULT_COLOR = 0x3399ff;
 
     Part(Score* score = nullptr);
+    ~Part();
     void initFromInstrTemplate(const InstrumentTemplate*);
 
     const muse::ID& id() const;

src/engraving/editing/editinstrumentchange.cpp

@@ -55,3 +55,19 @@
     // remember original instrument
     instrument = oi;
 }
+
+//---------------------------------------------------------
+//   ChangeInstrument::cleanup
+//---------------------------------------------------------
+
+void ChangeInstrument::cleanup(bool undo)
+{
+    // Delete the instrument pointer that is not currently in use
+    // After undo/redo, one of the instruments is no longer referenced
+    // The 'instrument' member holds the "other" instrument after flip
+    // We need to delete it when the undo command is being cleaned up
+    if (instrument) {
+        delete instrument;
+        instrument = nullptr;
+    }
+}

src/engraving/editing/editinstrumentchange.h

@@ -36,6 +36,7 @@ class ChangeInstrument : public UndoCommand
     Instrument* instrument = nullptr;
 
     void flip(EditData*) override;
+    void cleanup(bool undo) override;
 
 public:
     ChangeInstrument(InstrumentChange* _is, Instrument* i)