From 36653e8b300ec933d0800553035bbbe65bb7591a Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Tue, 20 Apr 2021 13:10:41 +0100
Subject: [PATCH] VST Host:  Correctly retrieve results of
 effGetSpeakerArrangement

The plugin should interpret the arguments as VstSpeakerArrangement**
instances. It should modify the pointed-to VstSpeakerArrangement* so
that it points to a long-lived VstSpeakerArrangement in the plugin.
---
 .../format_types/juce_VSTPluginFormat.cpp     | 45 ++++++++++---------
 1 file changed, 25 insertions(+), 20 deletions(-)

diff --git a/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp b/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp
index fa0e346b3e..8e9e1949d9 100644
--- a/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp
+++ b/modules/juce_audio_processors/format_types/juce_VSTPluginFormat.cpp
@@ -2186,20 +2186,14 @@ private:
                                       (pointer_sized_int) &canonicalIn.get(), (void*) &canonicalOut.get(), 0.0f);
         }
 
-        HeapBlock<Vst2::VstSpeakerArrangement> inArrBlock (1, true), outArrBlock (1, true);
-
-        auto* inArr  = inArrBlock.get();
-        auto* outArr = outArrBlock.get();
-
-        if (! getSpeakerArrangementWrapper (effect, inArr, outArr))
-            inArr = outArr = nullptr;
+        const auto arrangement = getSpeakerArrangementWrapper (effect);
 
         for (int dir = 0; dir < 2; ++dir)
         {
             const bool isInput = (dir == 0);
             const int opcode = (isInput ? Vst2::effGetInputProperties : Vst2::effGetOutputProperties);
             const int maxChannels = (isInput ? effect->numInputs : effect->numOutputs);
-            const Vst2::VstSpeakerArrangement* arr = (isInput ? inArr : outArr);
+            const auto* arr = (isInput ? arrangement.in : arrangement.out);
             bool busAdded = false;
 
             Vst2::VstPinProperties pinProps;
@@ -2250,12 +2244,7 @@ private:
 
     static bool pluginHasDefaultChannelLayouts (Vst2::AEffect* effect)
     {
-        HeapBlock<Vst2::VstSpeakerArrangement> inArrBlock (1, true), outArrBlock (1, true);
-
-        auto* inArr  = inArrBlock.get();
-        auto* outArr = outArrBlock.get();
-
-        if (getSpeakerArrangementWrapper (effect, inArr, outArr))
+        if (getSpeakerArrangementWrapper (effect).isValid())
             return true;
 
         for (int dir = 0; dir < 2; ++dir)
@@ -2283,19 +2272,35 @@ private:
         return false;
     }
 
-    static bool getSpeakerArrangementWrapper (Vst2::AEffect* effect,
-                                              Vst2::VstSpeakerArrangement* inArr,
-                                              Vst2::VstSpeakerArrangement* outArr)
+    struct SpeakerArrangements
+    {
+        const Vst2::VstSpeakerArrangement* in;
+        const Vst2::VstSpeakerArrangement* out;
+
+        bool isValid() const noexcept { return in != nullptr && out != nullptr; }
+    };
+
+    static SpeakerArrangements getSpeakerArrangementWrapper (Vst2::AEffect* effect)
     {
         // Workaround: unfortunately old JUCE VST-2 plug-ins had a bug and would crash if
         // you try to get the speaker arrangement when there are no input channels present.
         // Hopefully, one day (when there are no more old JUCE plug-ins around), we can
         // comment out the next two lines.
         if (effect->numInputs == 0)
-            return false;
+            return { nullptr, nullptr };
 
-        return (effect->dispatcher (effect, Vst2::effGetSpeakerArrangement, 0,
-                                          reinterpret_cast<pointer_sized_int> (&inArr), &outArr, 0.0f) != 0);
+        SpeakerArrangements result;
+        const auto dispatchResult = effect->dispatcher (effect,
+                                                        Vst2::effGetSpeakerArrangement,
+                                                        0,
+                                                        reinterpret_cast<pointer_sized_int> (&result.in),
+                                                        &result.out,
+                                                        0.0f);
+
+        if (dispatchResult != 0)
+            return result;
+
+        return { nullptr, nullptr };
     }
 
     //==============================================================================