VST3: Fixed invalid AudioProcessorParameterGroup unit IDs

modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp

@@ -233,7 +233,19 @@ public:
 
     static Vst::UnitID getUnitID (const AudioProcessorParameterGroup* group)
     {
-        return group == nullptr ? Vst::kRootUnitId : group->getID().hashCode();
+        if (group == nullptr || group->getParent() == nullptr)
+            return Vst::kRootUnitId;
+
+        // From the VST3 docs:
+        // Up to 2^31 parameters can be exported with id range [0, 2147483648]
+        // (the range [2147483649, 429496729] is reserved for host application).
+        auto unitID = group->getID().hashCode() & 0x7fffffff;
+
+        // If you hit this assertion then your group ID is hashing to a value
+        // reserved by the VST3 SDK. Use a different group ID.
+        jassert (unitID != Vst::kRootUnitId);
+
+        return unitID;
     }
 
     int getNumParameters() const noexcept             { return vstParamIDs.size(); }
@@ -263,6 +275,21 @@ private:
     {
         parameterGroups = audioProcessor->getParameterTree().getSubgroups (true);
 
+       #if JUCE_DEBUG
+        auto allGroups = parameterGroups;
+        allGroups.add (&audioProcessor->getParameterTree());
+        std::unordered_set<Vst::UnitID> unitIDs;
+
+        for (auto* group : allGroups)
+        {
+            auto insertResult = unitIDs.insert (getUnitID (group));
+
+            // If you hit this assertion then either a group ID is not unique or
+            // you are very unlucky and a hashed group ID is not unique
+            jassert (insertResult.second);
+        }
+       #endif
+
        #if JUCE_FORCE_USE_LEGACY_PARAM_IDS
         const bool forceLegacyParamIDs = true;
        #else

modules/juce_audio_processors/processors/juce_AudioProcessor.cpp

@@ -443,6 +443,24 @@ void AudioProcessor::checkForDuplicateParamID (AudioProcessorParameter* param)
    #endif
 }
 
+void AudioProcessor::checkForDuplicateGroupIDs (const AudioProcessorParameterGroup& newGroup)
+{
+    ignoreUnused (newGroup);
+
+   #if JUCE_DEBUG
+    auto groups = newGroup.getSubgroups (true);
+    groups.add (&newGroup);
+
+    for (auto* group : groups)
+    {
+        auto insertResult = groupIDs.insert (group->getID());
+
+        // If you hit this assertion then a group ID is not unique
+        jassert (insertResult.second);
+    }
+   #endif
+}
+
 const Array<AudioProcessorParameter*>& AudioProcessor::getParameters() const   { return flatParameterList; }
 const AudioProcessorParameterGroup& AudioProcessor::getParameterTree() const   { return parameterTree; }
 
@@ -461,6 +479,7 @@ void AudioProcessor::addParameter (AudioProcessorParameter* param)
 void AudioProcessor::addParameterGroup (std::unique_ptr<AudioProcessorParameterGroup> group)
 {
     jassert (group != nullptr);
+    checkForDuplicateGroupIDs (*group);
 
     auto oldSize = flatParameterList.size();
     flatParameterList.addArray (group->getParameters (true));
@@ -481,9 +500,12 @@ void AudioProcessor::setParameterTree (AudioProcessorParameterGroup&& newTree)
 {
    #if JUCE_DEBUG
     paramIDs.clear();
+    groupIDs.clear();
    #endif
 
     parameterTree = std::move (newTree);
+    checkForDuplicateGroupIDs (parameterTree);
+
     flatParameterList = parameterTree.getParameters (true);
 
     for (int i = 0; i < flatParameterList.size(); ++i)

modules/juce_audio_processors/processors/juce_AudioProcessor.h

@@ -1487,10 +1487,11 @@ private:
     #endif
 
     bool textRecursionCheck = false;
-    std::unordered_set<String> paramIDs;
+    std::unordered_set<String> paramIDs, groupIDs;
    #endif
 
     void checkForDuplicateParamID (AudioProcessorParameter*);
+    void checkForDuplicateGroupIDs (const AudioProcessorParameterGroup&);
 
     AudioProcessorListener* getListenerLocked (int) const noexcept;
     void updateSpeakerFormatStrings();