Confusing error when using COMReference on Core

[rainersigwald]

From @fubar-coder on Tuesday, 23 April 2019 07:16:19

I get an error which seems to be caused by the following COMReference project item:

  <ItemGroup Condition=" '$(TargetFramework)' == 'net461' and '$(OS)' == 'Windows_NT' ">
    <COMReference Include="ADOX.dll">
      <Guid>00000600-0000-0010-8000-00aa006d2ea4</Guid>
      <VersionMajor>6</VersionMajor>
      <VersionMinor>0</VersionMinor>
      <WrapperTool>tlbimp</WrapperTool>
      <Lcid>0</Lcid>
      <Isolated>false</Isolated>
    </COMReference>
  </ItemGroup>

The error message roughly translates to something along the lines: The "ResolveComReference" task couldn't be executed, because MSBuild couldn't create or connect to a task host with runtime "CLR4" and architecture "x86".

I also attached the build log.

build-log.zip

Copied from original issue: dotnet/installer#1690

[rainersigwald]

From @Pilchie on Tuesday, 23 April 2019 16:24:09

@rainersigwald do you know the state of COMReference in the SDK?

[rainersigwald]

From @rainersigwald on Tuesday, 23 April 2019 18:07:39

It's not expected to work, but it should fail in a clearer way than this. I think that's a bug for Microsoft/MSBuild; I'll move this and describe what the problem is there.

[rainersigwald]

COM reference resolution currently only works when building with MSBuild.exe. That's tracked by #3986. You should be able to build successfully with MSBuild.exe (targeting .NET Core 3.0).

This error is very confusing; we should instead give the error added in #3987, which should make the underlying problem clearer. This issue tracks the bad error, which I think is related to this:

https://github.com/Microsoft/msbuild/blob/64a5b6be6d4c1a45c02537a08dca8dd1db09f7f2/src/Tasks/Microsoft.Common.CurrentVersion.targets#L3019-L3043

I think we're trying to load a task in a specific TaskHost environment that we can't satisfy, which means we can't emit the error from the new task.

[rainersigwald]

Reproed with @Forgind; this only happens when PlatformTarget is x86.