Enums are not considered blittable by Emscripten / Blazor WASM AOT

[HurricanKai]

Description

In P/Invoke callbacks, Enums are not considered blittable.
This means no enums can be used as parameters of P/Invoke callbacks.

Reproduction Steps

Attempt to compile a method like

[UnmanagedCallersOnly]
public static void M(StringComparison myEnum) { }

using Emscripten / WASM AOT

Expected behavior

The above code should be possible. Enums should be considered blittable.

Actual behavior

An error is shown, enums are not considered blittable.

Regression?

No response

Known Workarounds

Use the underlying type of the enum (usually int) instead and manually cast.

Configuration

Tested in .NET 6 RC2

Other information

No response

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

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

Issue Details

---

Description

In P/Invoke callbacks, Enums are not considered blittable.
This means no enums can be used as parameters of P/Invoke callbacks.

Reproduction Steps

Attempt to compile a method like

[UnmanagedCallersOnly]
public static void M(StringComparison myEnum) { }

using Emscripten / WASM AOT

Expected behavior

The above code should be possible. Enums should be considered blittable.

Actual behavior

An error is shown, enums are not considered blittable.

Regression?

No response

Known Workarounds

Use the underlying type of the enum (usually int) instead and manually cast.

Configuration

Tested in .NET 6 RC2

Other information

No response

Author:	HurricanKai
Assignees:	-
Labels:	arch-wasm, untriaged, area-Interop-mono
Milestone:	-

[lambdageek]

related to #61146

[lambdageek]

I think the code in the runtime handles this. There just needs to be an IsEnum check in the pinvoke table generator.