Improve metadata annotations

[MarijnS95]

It's great to have winmd metadata available 🎉 but a few type annotations are missing.

IDStorageFactory::SetDebugFlags::flags should be DSTORAGE_DEBUG. And IDStorageQueue has non-optional output pointers, that don't seem to be properly represented in the metadata and cause windows-rs to generate a by-mutable-reference getter rather than allocating and returning the object.

All of that is solved with the following mapping.

--memberRemap
IDStorageFactory::SetDebugFlags::flags=[AssociatedEnum("DSTORAGE_DEBUG")]
IDStorageQueue::RetrieveErrorRecord::record=[RetVal]
IDStorageQueue::Query::info=[RetVal]

Tsukisoft/direct-storage-rs@6a7f8c5

[MarijnS95]

Note that when generating custom metadata (link above), the #defines from dstorageerr.h disappear. Were these mapped manually as enum constants when Microsoft generated the published .winmd?

There's a request to push the headers to this repo somewhere for convenient access, can the same be done for the (supposedly minimal) .csproj and emitter.settings.rsp (and other filtes) related to the .winmd build so that users can repro a similar file and contribute improvements like the ones suggested in the OP?

[paulbartrum]

Today I generated C# bindings for DirectStorage using CsWin32 and the winmd file from the DirectStorage Nuget package (v1.3.0).

I ran into a couple of issues. The biggest one is that pointers seem to be missing from structs that accept interfaces:

public partial struct DSTORAGE_QUEUE_DESC
{
    public winmdroot.DSTORAGE_REQUEST_SOURCE_TYPE SourceType;
    public ushort Capacity;
    public winmdroot.DSTORAGE_PRIORITY Priority;
    public global::Windows.Win32.Foundation.PSTR Name;
    public global::Windows.Win32.Graphics.Direct3D12.ID3D12Device Device;
}

public partial struct DSTORAGE_DESTINATION_BUFFER
{
    public global::Windows.Win32.Graphics.Direct3D12.ID3D12Resource Resource;
    public ulong Offset;
    public uint Size;
}

public partial struct DSTORAGE_DESTINATION_MULTIPLE_SUBRESOURCES_RANGE
{
    public global::Windows.Win32.Graphics.Direct3D12.ID3D12Resource Resource;
    public uint FirstSubresource;
    public uint NumSubresources;
}

Notice it's generated ID3D12Device and ID3D12Resource instead of ID3D12Device* and ID3D12Resource*.

The other issue is that the generated struct for DSTORAGE_REQUEST_OPTIONS is far from ideal:

public partial struct DSTORAGE_REQUEST_OPTIONS
{
	public byte _bitfield1;
	public winmdroot.__byte_7 Reserved1;
	public ulong _bitfield2;
}

But I'm not sure if anything can be done about this one as it's obviously due to the use of bitfields.