[Bug 45864] New: wine mono cannot load 64-bit DLLs

https://bugs.winehq.org/show_bug.cgi?id=45864

Bug ID: 45864
           Summary: wine mono cannot load 64-bit DLLs
           Product: Wine
           Version: 3.0.2
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: mscoree
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 62358
  --> https://bugs.winehq.org/attachment.cgi?id=62358
wine mono project and binaries

Attached is an example project that makes a PInvoke call to a custom native
function.  It produces HelloWorld.exe (from HelloWorld.cs) and HelloWorld.dll
(from HelloworldNative.cpp).

If I build a 32-bit HelloWorld.dll, I am able to run HelloWorld.exe in Wine
with a WINEPREFIX generated from both WINEARCH=wine32 and WINEARCH=wine64.

However, if I build a 64-bit HelloWorld.dll, I am unable to run HelloWorld.exe
in Wine with a WINEPREFIX generated from either WINEARCH=wine32 or
WINEARCH=wine64.  I wouldn't expect WINEARCH=wine32 to work for a 64-bit DLL,
but its surprising that WINEARCH=wine64 doesn't work.  (With WINEARCH=wine64
I'm otherwise able to run 64-bit native executables without a problem.)

The failure looks like this:
> > HelloWorld.exe
>
> 002f:err:mscoree:LoadLibraryShim error reading registry key for installroot
>
> Unhandled Exception:
> System.DllNotFoundException: HelloWorld
>   at (wrapper managed-to-native) HelloWorld.Hello:helloWorld ()
>   at HelloWorld.Hello.Main () [0x00001] in <93c08d3d3d384696aa77bc80f6a731c1>:0 
> [ERROR] FATAL UNHANDLED EXCEPTION: System.DllNotFoundException: HelloWorld
>   at (wrapper managed-to-native) HelloWorld.Hello:helloWorld ()
>   at HelloWorld.Hello.Main () [0x00001] in <93c08d3d3d384696aa77bc80f6a731c1>:0

It seems like Wine Mono is either running as a 32-bit process or something is
wrong with how Wine Mono's PInvoke DllImport searches for compatible DLLs.