net9 - Type System.Object is not blittable: Not a ValueType

[Dona278]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

After update a blazor wasm hosted project from net8 to net9 during build / publish I see this in the build output:

message WASM0060: Type System.Object is not blittable: Not a ValueType
message WASM0062: Type System.Runtime.InteropServices.HandleRef is not blittable: Field _wrapper is not blittable
warning WASM0001: Could not get pinvoke, or callbacks for method 'Microsoft.Build.Framework.NativeMethods::GetModuleFileName' because 'System.NotSupportedException: Unsupported parameter type in method 'Microsoft.Build.Framework.NativeMethods.GetModuleFileName'
warning WASM0001:    at PInvokeCollector.<CollectPInvokes>g__CollectPInvokesForMethod|6_0(MethodInfo method, <>c__DisplayClass6_0& )
warning WASM0001:    at PInvokeCollector.CollectPInvokes(List`1 pinvokes, List`1 callbacks, HashSet`1 signatures, Type type)'

However it seems to works good, but I don't know what generate this warning and what are the conseguences.

Expected Behavior

No see this warning in the output

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

9.0.100

Anything else?

.NET SDK:
Version: 9.0.100
Commit: 59db016f11
Workload version: 9.0.100-manifests.c6f19616
MSBuild version: 17.12.7+5b8665660

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22631
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\9.0.100\

.NET workloads installed:
[wasm-tools]
Installation Source: SDK 9.0.100
Manifest Version: 9.0.0/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.workload.mono.toolchain.current\9.0.0\WorkloadManifest.json
Install Type: Msi

[wasm-tools-net8]
Installation Source: SDK 9.0.100
Manifest Version: 9.0.0/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.workload.mono.toolchain.net8\9.0.0\WorkloadManifest.json
Install Type: Msi

Configured to use loose manifests when installing new manifests.

Host:
Version: 9.0.0
Architecture: x64
Commit: 9d5a6a9

.NET SDKs installed:
8.0.404 [C:\Program Files\dotnet\sdk]
9.0.100-rc.2.24474.11 [C:\Program Files\dotnet\sdk]
9.0.100 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0-rc.2.24474.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0-rc.2.24473.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 8.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.0-rc.2.24474.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.0 [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:
C:\Sources\release\global.json

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

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

[javiercn]

@Dona278 thanks for contacting us.

Do you see this during Linking/ AoT compilation?

[Dona278]

@javiercn yes sorry!! I omitted probably the most important setup..
This is a blazor wasm hosted project with RCL referenced as nuget package and both AOT and Trimming enabled as full in the main project and partial in the RCL.

[Dona278]

As soon as I find 5 minutes today I try to write you the exact moment during build but for now I remember the was just before linking the assemblies yes

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

[Dona278]

As additional information. The warning appear also during normal build which AOT and Linking aren't involved in the process.

[pavelsavara]

@Dona278
Could you please add steps to reproduce ? Maybe sample repository.

[Dona278]

@pavelsavara sorry for the delay but I started from our main project and then remove a piece of code each time to reproduce the smallest repo as possible and I found the issue!
Reference a project which has Microsoft.Build.Utilities.Core as package reference (used to create MSBuild task code) lead to the error described in the issue if the main project has <WasmEnableSIMD>false</WasmEnableSIMD>

To reproduce:
Library.csproj

<Project Sdk="Microsoft.NET.Sdk">

	<PropertyGroup>
		<TargetFramework>netstandard2.0</TargetFramework>
		<LangVersion>preview</LangVersion>
		<Nullable>enable</Nullable>
	</PropertyGroup>

	<ItemGroup>
		<PackageReference Include="Microsoft.Build.Utilities.Core" Version="17.12.6" />
	</ItemGroup>

</Project>

Blazor.Web.csproj

<Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly">

	<PropertyGroup>
		<TargetFramework>net9.0</TargetFramework>
		<LangVersion>preview</LangVersion>
		<Nullable>enable</Nullable>
		<ImplicitUsings>enable</ImplicitUsings>
		<NoWarn>$(NoWarn);1591</NoWarn>

		<WasmEnableSIMD>false</WasmEnableSIMD>
	</PropertyGroup>

	<ItemGroup>
		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="9.0.0" />
		<PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="9.0.0" PrivateAssets="all" />
		<PackageReference Include="Microsoft.Extensions.Logging.Configuration" Version="9.0.0" />
	</ItemGroup>

	<ItemGroup>
		<ProjectReference Include="..\..\Library\Library.csproj" />
	</ItemGroup>

</Project>

If you remove the PackageReference or the WasmEnableSIMD item the error disappear.

[pavelsavara]

I guess you are not trying to run MSBuild inside of the browser. I suggest that you separate that part of Library.csproj into another project, which you would not reference from Blazor.Web.csproj

[Dona278]

Library already contains only code for custom msbuild task, and it is referenced in blazor (web) with PrivateAssets="all" because some tasks are used at build time. So yes the library is used in a web project, is it wrong?