Add stubs for IPlugInterfaceSupport

src/wine-host/bridges/vst3-impls/host-context-proxy.cpp

@@ -93,3 +93,12 @@ Vst3HostContextProxyImpl::createInstance(Steinberg::TUID /*cid*/,
 
     return response;
 }
+
+tresult PLUGIN_API
+Vst3HostContextProxyImpl::isPlugInterfaceSupported(const Steinberg::TUID _iid) {
+    // TODO: Implement
+    std::cerr
+        << "TODO: Implement IPlugInterfaceSupport::isPlugInterfaceSupported()"
+        << std::endl;
+    return Steinberg::kNotImplemented;
+}

src/wine-host/bridges/vst3-impls/host-context-proxy.h

@@ -36,6 +36,10 @@ class Vst3HostContextProxyImpl : public Vst3HostContextProxy {
                                       Steinberg::TUID _iid,
                                       void** obj) override;
 
+    // From `IPlugInterfaceSupport`
+    tresult PLUGIN_API
+    isPlugInterfaceSupported(const Steinberg::TUID _iid) override;
+
    private:
     Vst3Bridge& bridge;
 };

src/wine-host/bridges/vst3.cpp

@@ -804,10 +804,12 @@ void Vst3Bridge::run() {
                 //      start timers from here.
                 return main_context
                     .run_in_context<tresult>([&]() {
+                        // This static cast is required to upcast to `FUnknown*`
                         return object_instances[request.instance_id]
                             .plugin_base->initialize(
-                                object_instances[request.instance_id]
-                                    .host_context_proxy);
+                                static_cast<YaHostApplication*>(
+                                    object_instances[request.instance_id]
+                                        .host_context_proxy));
                     })
                     .get();
             },
@@ -876,7 +878,10 @@ void Vst3Bridge::run() {
                     module->getFactory().get());
                 assert(factory_3);
 
-                return factory_3->setHostContext(plugin_factory_host_context);
+                // This static cast is required to upcast to `FUnknown*`
+                return factory_3->setHostContext(
+                    static_cast<YaHostApplication*>(
+                        plugin_factory_host_context));
             },
             [&](const YaUnitInfo::GetUnitCount& request)
                 -> YaUnitInfo::GetUnitCount::Response {