EnableComHosting usage results in MSB4018 GenerateClsidMap task failure

[riverar]

Describe the bug

When <EnableComHosting> is set to True, compilation of a class library with GeneratedComInterface and GeneratedComClass attributes fails with an obscure error.

Things I checked:

• There is no visible SYSLIB error emitted.
• Tutorial documentation doesn't explicitly cover use of these attributes, it's not clear if they're supported or not

It appears COM hosting and source-generated COM is not supported but neither the docs or error messages say anything helpful.

To Reproduce

1. git clone https://github.com/riverar/repro-807e6dbdca02
2. dotnet build
3. Observe error

Exceptions (if any)

The "GenerateClsidMap" task failed unexpectedly.
System.InvalidCastException: Specified cast is not valid.
   at System.Reflection.Throw.InvalidCast()
   at System.Reflection.Metadata.TypeReferenceHandle.op_Explicit(EntityHandle handle)
   at Microsoft.NET.HostModel.ComHost.ClsidMap.IsTargetAttribute(MetadataReader reader, CustomAttribute attribute, String targetNamespace, String targetName)
   at Microsoft.NET.HostModel.ComHost.ClsidMap.GetComVisibleAttribute(MetadataReader reader, CustomAttributeHandleCollection customAttributes)
   at Microsoft.NET.HostModel.ComHost.ClsidMap.<IsComVisible>g__IsComVisibleCore|9_0(TypeDefinition typeDefinition, <>c__DisplayClass9_0& )
   at Microsoft.NET.HostModel.ComHost.ClsidMap.IsComVisible(MetadataReader metadataReader, TypeDefinition definition, Boolean assemblyComVisible)
   at Microsoft.NET.HostModel.ComHost.ClsidMap.Create(MetadataReader metadataReader, String clsidMapPath)
   at Microsoft.NET.Build.Tasks.GenerateClsidMap.ExecuteCore()
   at Microsoft.NET.Build.Tasks.TaskBase.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()

Further technical details

details of dotnet --info

.NET SDK: Version: 10.0.101 Commit: fad253f51b Workload version: 10.0.100-manifests.9f71effe MSBuild version: 18.0.6+fad253f51

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26220
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.101\

.NET workloads installed:
[ios]
Installation Source: VS 18.3.11312.210
Manifest Version: 26.1.10502/10.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.ios\26.1.10502\WorkloadManifest.json
Install Type: Msi

[maccatalyst]
Installation Source: VS 18.3.11312.210
Manifest Version: 26.1.10502/10.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.maccatalyst\26.1.10502\WorkloadManifest.json
Install Type: Msi

[android]
Installation Source: VS 18.3.11312.210
Manifest Version: 36.1.2/10.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.android\36.1.2\WorkloadManifest.json
Install Type: Msi

[maui-windows]
Installation Source: VS 18.3.11312.210
Manifest Version: 10.0.1/10.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.maui\10.0.1\WorkloadManifest.json
Install Type: Msi

Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.1
Architecture: x64
Commit: fad253f51b

.NET SDKs installed:
8.0.416 [C:\Program Files\dotnet\sdk]
10.0.101 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 7.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Microsoft Visual Studio Enterprise
Channel: Insiders
Version: Insiders [11312.210]

#4099 seems related but was closed.