Work around improperly late initializing plugins

This fixes the Roland Cloud plugins.

src/common/events.h

@@ -283,6 +283,14 @@ auto passthrough_event(AEffect* plugin, F callback) {
             [&](DynamicSpeakerArrangement& speaker_arrangement) -> void* {
                 return &speaker_arrangement.as_c_speaker_arrangement();
             },
+            [&](WantsAEffectUpdate&) -> void* {
+                // The host will never actually ask for an updated `AEffect`
+                // object since that should not be a thing. This is purely a
+                // meant as a workaround for plugins that initialize their
+                // `AEffect` object after the plugin has already finished
+                // initializing.
+                return nullptr;
+            },
             [&](WantsChunkBuffer&) -> void* { return string_buffer.data(); },
             [&](VstIOProperties& props) -> void* { return &props; },
             [&](VstMidiKeyName& key_name) -> void* { return &key_name; },
@@ -335,6 +343,7 @@ auto passthrough_event(AEffect* plugin, F callback) {
             [&](VstParameterProperties& props) -> EventResultPayload {
                 return props;
             },
+            [&](WantsAEffectUpdate&) -> EventResultPayload { return *plugin; },
             [&](WantsVstRect&) -> EventResultPayload {
                 // The plugin has written a pointer to a VstRect struct into the
                 // data poitner

src/common/logging.cpp

@@ -201,14 +201,15 @@ void Logger::log_event(bool is_dispatch,
                     message << "<" << speaker_arrangement.speakers.size()
                             << " output_speakers>";
                 },
-                [&](const WantsChunkBuffer&) {
-                    message << "<writable_buffer>";
-                },
                 [&](const VstIOProperties&) { message << "<io_properties>"; },
                 [&](const VstMidiKeyName&) { message << "<key_name>"; },
                 [&](const VstParameterProperties&) {
                     message << "<writable_buffer>";
                 },
+                [&](const WantsAEffectUpdate&) { message << "<nullptr>"; },
+                [&](const WantsChunkBuffer&) {
+                    message << "<writable_buffer>";
+                },
                 [&](const WantsVstRect&) { message << "<writable_buffer>"; },
                 [&](const WantsVstTimeInfo&) { message << "<nullptr>"; },
                 [&](const WantsString&) { message << "<writable_string>"; }},

src/common/serialization.h

@@ -285,6 +285,15 @@ class alignas(16) DynamicSpeakerArrangement {
     std::vector<uint8_t> speaker_arrangement_buffer;
 };
 
+/**
+ * Marker struct to indicate that the other side (the Wine VST host) should send
+ * an updated copy of the plugin's `AEffect` object. Should not be needed since
+ * the plugin should be calling `audioMasterIOChanged()` after it has changed
+ * its object, but some improperly coded plugins will only initialize their
+ * flags, IO properties and parameter counts after `effEditOpen()`.
+ */
+struct WantsAEffectUpdate {};
+
 /**
  * Marker struct to indicate that that the event writes arbitrary data into one
  * of its own buffers and uses the void pointer to store start of that data,
@@ -352,6 +361,7 @@ using EventPayload = std::variant<std::nullptr_t,
                                   AEffect,
                                   DynamicVstEvents,
                                   DynamicSpeakerArrangement,
+                                  WantsAEffectUpdate,
                                   WantsChunkBuffer,
                                   VstIOProperties,
                                   VstMidiKeyName,
@@ -382,8 +392,9 @@ void serialize(S& s, EventPayload& payload) {
               [](S& s, VstIOProperties& props) { s.object(props); },
               [](S& s, VstMidiKeyName& key_name) { s.object(key_name); },
               [](S& s, VstParameterProperties& props) { s.object(props); },
-              [](S&, WantsChunkBuffer&) {}, [](S&, WantsVstRect&) {},
-              [](S&, WantsVstTimeInfo&) {}, [](S&, WantsString&) {}});
+              [](S&, WantsAEffectUpdate&) {}, [](S&, WantsChunkBuffer&) {},
+              [](S&, WantsVstRect&) {}, [](S&, WantsVstTimeInfo&) {},
+              [](S&, WantsString&) {}});
 }
 
 /**