We can now use implement all VST3 plugin interfaces through this class,
check whether the object from the plugin also supports these classes,
and then conditionally allow casting to the supported classes. This
should give us a one-to-one proxy of the original object.
Directly serializing and deserializing into objects was and more
boilerplate heavy (since we now need two implementations even though we
only use one), and also much less flexible because we can't wrap
payloads in structs or provide optional values that way.
Since the object cleans up after itself after the smart pointers are
dropped on the host side this would result in a use after free by the
smart pointers.
This now takes a regular overloaded function and the visiting is done in
`receive_messages()` itself. This way we can use templates to ensure
that the return type is correct. Otherwise auto will cause issues in the
future when we want to return multiple concrete types from a function
that takes a single variant. The alternative would be both receiving a
variant as a parameter and then returning another variant as a result,
but that is much less type safe.
- Now allows direct deserialization into existing objects. This will be
necessary for our VST3 implementations since the interface instances
we'll deserialize into will not be trivially constructable because
they have to be able to do callbacks.
- `ControlResponse` and `CallbackResponse` were dropped. These response
enums are not necessary because of the `T::Response` associated type
and returning the types directly makes the direct deserialization
possible.
To account for the differences in VST2 plugins and VST3 modules we had
to wrap most of our old functions from `src/plugin/utils.h` in a new
`PluginInfo` struct that gathers all of this information while taking
into account the differences between VST2 and VST3 plugins.
With this change things are also a lot more organized. We can just query
the plugin information we need rather than having to store things
separately or having to recalculate things. This also moved the
responsibility of all the weird `WINEPREFIX` behaviour to a single place
instead of having it spread around `utils.pp`, the initialisation
message, and `host-procoess.cpp`.
Robbert van der Helm