Trimming implication of IDispatch

[MichalStrehovsky]

IDispatch COM interface is basically reflection.

We need to investigate what it means for trimming. Does the runtime provide an implementation of this? If so, linker needs to make this 100% work, or surface warnings somehow.

[jkoritzinsky]

Yes, the runtime provides an implementation of IDispatch and exposes any interfaces marked with [InterfaceTypeAttribute (ComInterfaceType.InterfaceIsIDispatch)]. It also exposes the class type if it is marked with [ClassInterfaceAttribute].

The runtime will also generate an IDispatch interface for any type which is [ComVisible(true)] or that is in an assembly which is [ComVisible(true)] and is not marked [ComVisible(false)]. Members of base classes of ComVisible types can be exposed via IDispatch as well.

[MichalStrehovsky]

Thanks! I ended up having a thread with Aaron on this. We basically decided that we will just try to detect COM and warn on any usage.

#1382 tries to do at least partial detection and issue warnings. There are way too many ways to get to COM in .NET.