Problem with CsWin32 generated entry point function

[youyuanwu]

In idl file, the entry point function is declared like this:

    [
        uuid(fefc1487-3c52-4ea1-a8eb-19cd7ec533e6),
        dllname("FabricClient.dll")
    ]
    module FabricClientModule {
        [entry("FabricCreateLocalClient")] HRESULT FabricCreateLocalClient(
            [in] REFIID iid,
            [out, retval] void ** fabricClient);
     }

The generated code is:

namespace Microsoft.ServiceFabric
{
    [GeneratedCode("Microsoft.Windows.CsWin32", "0.3.18-beta+dc807e7787")]
    public static class PInvoke
    {
        public static HRESULT FabricCreateLocalClient(in Guid iid, out void* fabricClient);
        [DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
        public static HRESULT FabricCreateLocalClient(Guid* iid, void** fabricClient);
    }
}

One can use the second (raw types) function like this (not sure if it is correct):

unsafe {
    var guid = typeof(IFabricQueryClient).GUID;
    var clientRaw = IntPtr.Zero;
    HRESULT hr = PInvoke.FabricCreateLocalClient(&guid, (void**)&clientRaw);

    Debug.Assert(hr.Succeeded);
   
    var cc = Marshal.PtrToStructure<IFabricQueryClient>(clientRaw);
    Debug.Assert(cc != null);
};

But it is unclear how to use the first with out void*.

The other problem is that the dll cannot be loaded:

> dotnet run --project .\src\examples\examples.csproj        
Unhandled exception. System.DllNotFoundException: Unable to load DLL 'FabricClient' or one of its dependencies: The specified module could not be found. (0x8007007E)
   at Microsoft.ServiceFabric.PInvoke.FabricCreateLocalClient(Guid* iid, Void** fabricClient)
   at Program.<Main>$(String[] args) in D:\code\cs\service-fabric-cs\src\examples\Program.cs:line 29

Service Fabric dlls are in system path, but in directory C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code. Maybe the DefaultDllImportSearchPaths should be customized.
Maybe related to microsoft/CsWin32#968

[youyuanwu]

@AArnott @riverar for CsWin32 help again. Thanks.

[AArnott]

Interesting. We touched close to this in microsoft/CsWin32#617, but it was a different use case and the fix won't help here. Can you file a new issue against CsWin32?

[youyuanwu]

Following the suggestion in microsoft/CsWin32#1029 to use LoadLibrary directly, the dll is loaded and used by PInvoke.