Use the known_iids mechanism for IComponent

src/common/serialization/vst3/README.md

@@ -70,6 +70,10 @@ instantiated and managed by the host. The basic model works as follows:
    native plugin in a `known_iids` set. In our query interface method we then
    only report support for the same interfaces that were supported by the
    original `IPtr<IPluginFactory` we're proxying.
+7. The same mechanism that we use for versioning is also used for objects that
+   commonly implement multiple interfaces. A common example of this is an
+   `IComponent` (which inherits from `IPluginBase`) also implementing
+   `IAudioProcessor` and `IConnectionPoint`.
 
 ## Interface Instantiation
 

src/common/serialization/vst3/component.cpp

@@ -22,11 +22,14 @@ YaComponent::ConstructArgs::ConstructArgs(
     Steinberg::IPtr<Steinberg::Vst::IComponent> component,
     size_t instance_id)
     : instance_id(instance_id) {
+    known_iids.insert(component->iid);
     // `IComponent::getControllerClassId`
     Steinberg::TUID cid;
     if (component->getControllerClassId(cid) == Steinberg::kResultOk) {
         edit_controller_cid = std::to_array(cid);
     }
+
+    // TODO: Add support of IAudioProcessor
 }
 
 YaComponent::YaComponent(const ConstructArgs&& args) : arguments(std::move(args)) {
@@ -48,10 +51,13 @@ IMPLEMENT_REFCOUNT(YaComponent)
 tresult PLUGIN_API YaComponent::queryInterface(Steinberg::FIDString _iid,
                                                void** obj) {
     QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid, Steinberg::IPluginBase)
-    QUERY_INTERFACE(_iid, obj, Steinberg::IPluginBase::iid,
-                    Steinberg::IPluginBase)
-    QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IComponent::iid,
-                    Steinberg::Vst::IComponent)
+    if (arguments.known_iids.contains(Steinberg::Vst::IComponent::iid)) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::IPluginBase::iid,
+                        Steinberg::IPluginBase)
+        QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IComponent::iid,
+                        Steinberg::Vst::IComponent)
+    }
+    // TODO: Add IAudioProcessor
 
     *obj = nullptr;
     return Steinberg::kNoInterface;

src/common/serialization/vst3/component.h

@@ -17,14 +17,17 @@
 #pragma once
 
 #include <optional>
+#include <set>
 #include <variant>
 
 #include <bitsery/ext/pointer.h>
 #include <bitsery/ext/std_optional.h>
+#include <bitsery/ext/std_set.h>
 #include <bitsery/ext/std_variant.h>
 #include <bitsery/traits/array.h>
 #include <pluginterfaces/vst/ivstcomponent.h>
 
+#include "../../bitsery/ext/vst3.h"
 #include "../common.h"
 #include "base.h"
 #include "host-application.h"
@@ -55,7 +58,9 @@ class YaComponent : public Steinberg::Vst::IComponent {
         ConstructArgs();
 
         /**
-         * Read arguments from an existing implementation.
+         * Read arguments from an existing implementation. Depending on the
+         * supported interface function more or less of this struct will be left
+         * empty, and `known_iids` will be set accordingly.
          */
         ConstructArgs(Steinberg::IPtr<Steinberg::Vst::IComponent> component,
                       size_t instance_id);
@@ -65,6 +70,11 @@ class YaComponent : public Steinberg::Vst::IComponent {
          */
         native_size_t instance_id;
 
+        /**
+         * The IIDs that the interface we serialized supports.
+         */
+        std::set<Steinberg::FUID> known_iids;
+
         /**
          * The class ID of this component's corresponding editor controller. You
          * can't use C-style array in `std::optional`s.
@@ -74,6 +84,10 @@ class YaComponent : public Steinberg::Vst::IComponent {
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
+            s.ext(known_iids, bitsery::ext::StdSet{32},
+                  [](S& s, Steinberg::FUID& iid) {
+                      s.ext(iid, bitsery::ext::FUID{});
+                  });
             s.ext(edit_controller_cid, bitsery::ext::StdOptional{},
                   [](S& s, auto& cid) { s.container1b(cid); });
         }

src/common/serialization/vst3/plugin-factory.h

@@ -48,7 +48,7 @@ class YaPluginFactory : public Steinberg::IPluginFactory3 {
         /**
          * Create a copy of an existing plugin factory. Depending on the
          * supported interface function more or less of this struct will be left
-         * empty, and `iid` will be set accordingly.
+         * empty, and `known_iids` will be set accordingly.
          */
         ConstructArgs(Steinberg::IPtr<Steinberg::IPluginFactory> factory);