[browser][MT] WasmEnableThreads=true should fail without workload installed

[SteveSandersonMS]

Description

The wasm-tools workload is required to build a multithreading-enabled WebAssembly app.

By default, people do not have the wasm-tools workload installed. In this scenario, if they create a Blazor WebAssembly app and set <WasmEnableThreads>true</WasmEnableThreads>, then it will fail at runtime as follows:

This doesn't help the developer to understand the problem or how to fix it.

Reproduction Steps

Using an SDK without wasm-tools, create a .NET 9 Blazor WebAssembly Standalone app, set <WasmEnableThreads>true</WasmEnableThreads>, and dotnet run.

Expected behavior

Ideally it would fail at build time with a message like WasmEnableThreads is set to true, but the wasm-tools workload is not installed. To build this project, first run 'dotnet workload install wasm-tools'.

The second best behavior would be failing at runtime with a message like the above.

Actual behavior

Currently it fails saying "Can't find method ... InstallMainSynchronizationContext", giving no clue how to fix it.

Regression?

No

Known Workarounds

n/a

Configuration

.NET 9 + WebAssembly

Other information

No response

[SteveSandersonMS]

cc @lewing @pavelsavara

[ghost]

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

Issue Details

---

Description

The wasm-tools workload is required to build a multithreading-enabled WebAssembly app.

By default, people do not have the wasm-tools workload installed. In this scenario, if they create a Blazor WebAssembly app and set <WasmEnableThreads>true</WasmEnableThreads>, then it will fail at runtime as follows:

This doesn't help the developer to understand the problem or how to fix it.

Reproduction Steps

Using an SDK without wasm-tools, create a .NET 9 Blazor WebAssembly Standalone app, set <WasmEnableThreads>true</WasmEnableThreads>, and dotnet run.

Expected behavior

Ideally it would fail at build time with a message like WasmEnableThreads is set to true, but the wasm-tools workload is not installed. To build this project, first run 'dotnet workload install wasm-tools'.

The second best behavior would be failing at runtime with a message like the above.

Actual behavior

Currently it fails saying "Can't find method ... InstallMainSynchronizationContext", giving no clue how to fix it.

Regression?

No

Known Workarounds

n/a

Configuration

.NET 9 + WebAssembly

Other information

No response

Author:	SteveSandersonMS
Assignees:	-
Labels:	arch-wasm, untriaged, area-Build-mono, os-browser
Milestone:	-

[pavelsavara]

I think this WasmEnableThreads needs to be added to _WasmNativeWorkloadNeeded.
Right @maraf ?

[lewing]

#98498

[ilonatommy]

HostedBlazorWebassemblyApp sample app with threads on - installing workload does not help with the error, why do we link it with workloads?

.NET SDK:
 Version:           9.0.100-preview.2.24112.1
 Commit:            ab44b49a39
 Workload version:  9.0.100-manifests.18bf7498

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.22621
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Users\..\aspnetcore\aspnetcore\.dotnet\sdk\9.0.100-preview.2.24112.1\

.NET workloads installed:
 [wasm-tools]
   Installation Source: SDK 9.0.100-preview.2
   Manifest Version:    9.0.0-preview.2.24115.1/9.0.100-preview.2
   Manifest Path:       C:\Users\..\aspnetcore\aspnetcore\.dotnet\sdk-manifests\9.0.100-preview.2\microsoft.net.workload.mono.toolchain.current\9.0.0-preview.2.24115.1\WorkloadManifest.json
   Install Type:        FileBased

[lewing]

HostedBlazorWebassemblyApp sample app with threads on - installing workload does not help with the error, why do we link it with workloads?

.NET SDK:
 Version:           9.0.100-preview.2.24112.1
 Commit:            ab44b49a39
 Workload version:  9.0.100-manifests.18bf7498

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.22621
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Users\..\aspnetcore\aspnetcore\.dotnet\sdk\9.0.100-preview.2.24112.1\

.NET workloads installed:
 [wasm-tools]
   Installation Source: SDK 9.0.100-preview.2
   Manifest Version:    9.0.0-preview.2.24115.1/9.0.100-preview.2
   Manifest Path:       C:\Users\..\aspnetcore\aspnetcore\.dotnet\sdk-manifests\9.0.100-preview.2\microsoft.net.workload.mono.toolchain.current\9.0.0-preview.2.24115.1\WorkloadManifest.json
   Install Type:        FileBased

Yeah, I'm not 100% sure this failure is related but making sure the workload is installed for mt will reduce configurations we're testing for MT immediately which will reduce the search space.

[maraf]

The reported error has the same cause as #98502. MT apps should be working without workload